Microbiology KP notes Flashcards

Question

what is the use of XLD agar?

Answer 1

used to differentiate Salmonella and Shigella mainly

Answer 2

- Gram negative bacilli only - will turn pink/red if lactose fermenting bacteria e.g. E. coli - will turn white/transparent if non-lactose fermenting e.g. Salmonella

Answer 3

Salmonella = red/pink colonies some with black spots Shigella = red/pink colonies

Answer 4

- Staphylococci - Streptococci - Enterococci - anaerobic Streptococci e.g. peptostreptococci

Answer 5

- Neisseria - Moraxella - anaerobic cocci e.g. Veillonella spp.

Answer 6

- Bacillus e.g. B. anthracis - Clostridia - Corynebacteria e.g. C. diptheriae - Listeria monocytogenes - anaerobic bacilli e.g. Clostridia - Propionibacteria

Answer 7

- E. coli - Campylobacter - Pseudomonas - Salmonella - Shigella - Proteus

Answer 8

staphylococcus and streptococcus

Answer 9

S. aureus and S. epidermidis

Answer 10

peptostreptococcus

Answer 11

Bacteroides (e.g. B. fragilis)

Answer 12

- coliforms - pseudomonads - vibrio - parvobacteria

Answer 13

non-sterile: nasal cavity, larynx, stomach, colon sterile: lungs, gall bladder, kidneys, eye, CSF

Answer 14

- you measure bacterial growth by shining light on bacteria and measuring absorption - bacteria divide by binary fission - the growth lag is due to the fact the bacteria are taking in the nutrients needed to divide and grow - then there is exponential growth until the nutrient runs out - viable = death phase

Answer 15

the genetic alteration of a bacterial cell via the uptake of an exogenous substance e.g. via plasmid

Answer 16

process by which foreign DNA is introduced into a bacteria via vector or virus e.g. via a bacteriophage (virus)

Answer 17

the transfer of genetic material between bacterial cells by direct cell-cell contact e.g. via sex pilus

Answer 18

- normal habitat is on the nose and skin - at least 40 species - can be coagulase positive (clumping) or negative (no clumping) - coagulase converts fibrinogen to fibrin i.e. clot - some bacteria produce it to protect against white blood cells e.g. S. aureus

Answer 19

- pain in shoulder - elevated temperature - MRI scan - disc injection and osteomyelitis (bone infection) C6 and C7 - blood cultures show staphylococcus aureus - treat with flucloxacillin (antibiotic) for 3 months - Staph. aureus is responsible for around 90% of osteomyelitis

Answer 20

aerosol and touch e.g. coughing and breathing

Answer 21

* Beta-lactams antibiotics * gentamicin * erythromycin * tetracycline

Answer 22

- pore-forming toxins (some produce these) e.g: • PVL toxin which is prodcued by many MRSA strains and causes haemorrhagic pneumonia • alpha-haemolysin which can induce apoptosis (at low levels) or cause widespread necrosis (at high levels) - proteases e.g: • exfoliatin which causes scalded skin syndrome - toxic shock syndrome toxin (TSST) which stimulates cytokine release - protein A which is a surface protein which binds immunoglobulins in wrong orientation

Answer 23

• PVL toxin which is prodcued by many MRSA strains and causes haemorrhagic pneumonia • alpha-haemolysin which can induce apoptosis (at low levels) or cause widespread necrosis (at high levels)

Answer 24

- wound infections (staph. aureus is very good at colonising these) - abscesses - osteomyelitis - scalded skin syndrome - toxic shock syndrome - food poisoning

Answer 25

S. epidermis and S. saprophyticus

Answer 26

- opportunistic infections in prosthetic limbs and catheters | - its main virulence factor is its ability to form persistent biofilms

Answer 27

acute cystitis

Answer 28

* haemolysis * Lancefield typing * biochemical properties

Answer 29

a method of grouping catalase negative and coagulase negative bacteria based on the bacterial carbohydrate cell surface antigens

Answer 30

Group A - Strep. pyogenes | Group B - Strep. agalactiae; neonatal infections

Answer 31

- wound infections such as cellulitis - tonsillitis and pharyngitis - otitis media - scarlet fever (caused by erythrogenic toxin)

Answer 32

- rheumatic fever - glomerulonephritis - some strains produce erythrogenic toxin which is responsible for scarlet fever, this toxin is a super-antigen meaning it gives rise to an exaggerated immunological response and increased circulating cytokine levels - infection with any strain of Strep pyogenes can give rise to complications that are immunologically mediated, so prompt treatment is required to reduce risks - assessment of risk can be estimated from the anti-streptolysin O titre

Answer 33

anti-streptolysin O titre

Answer 34

* hyaluronidase - spreading * streptokinase - breaks down clots * C5a peptidase - reduces chemotaxis * streptolysins O & S toxin - binds cholesterol * erythrogenic toxin - exaggerated response

Answer 35

breaks down clots

Answer 36

reduces chemotaxis

Answer 37

binds cholesterol

Answer 38

exaggerated response

Answer 39

* hyaluronic acid capsule - protection | * M protein - surface protein that encourages complement degradation

Answer 40

protection

Answer 41

surface protein that encourages complement degradation

Answer 42

- heavy smoker with nasal congestion and fever - 2 days later gets cough and severe chest pain - rust-coloured sputum - chest X-ray shows consolidation (lung filled with liquid) - blood and sputum culture show Strep. pneumoniae (draughtsman colonies)

Answer 43

- pneumonia - otitis media (middle ear infection) - sinusitis - meningitis

Answer 44

- impaired mucus trapping e.g. viral infection - hypogammaglobulinemia - low levels of serum immunoglobulins which are required for efficient phagocytosis - asplenia - since spleen produces protein called tuftsin which acts to enhance phagocytosis so with no spleen then no tuftsin and this impairs phagocytosis and thus risk of infection - diabetes - renal disease - sickle cell disease - very young (younger than 2) since immune response to polysaccharide antigens is very poor

Answer 45

- polysaccharide capsule (84 types) - is antiphagocytic - there is a polyvalent vaccine available for those under 2 but this only protects against 23/84 types - teichoic acid binds to choline receptors - peptidoglycan helps protect bacteria - pneumolysin cytotoxin is a pore-forming toxin

Answer 46

(84 types) - is antiphagocytic - there is a polyvalent vaccine available for those under 2 but this only protects against 23/84 types

Answer 47

binds to choline receptors

Answer 48

helps protect bacteria

Answer 49

pore-forming toxin

Answer 50

* collective name for oral streptococci * alpha or non-haemolytic * some cause dental caries and abscesses

Answer 51

S. sanguis and S. oralis

Answer 52

most pathogenic are the milleri group: - S. intermedius - S. anginosis - S. constellatus - causing deep organ abscesses e.g. in brain & liver

Answer 53

* child with severe sore throat * fever and malaise for 2 days * lymphadenopathy (swollen) in neck * rapid breathing * thick greyish membrane on tonsils

Answer 54

gram positive rods/bacilli

Answer 55

treated with anti-toxin (pre-formed antibody to toxin) and erythromycin (antibiotic helps remove symptoms and stop carriage and spread but does not destroy pathogen)

Answer 56

droplet spread

Answer 57

caused by the production of a toxin which inhibits protein synthesis (inactivates elongation factor-2 in host cells by adding ADP-ribosyl group to aa dipthamide)

Answer 58

- prevention by vaccination with toxoid (inactivated toxin) - can grow in the presence of potassium tellurite - selective method for isolating this bacteria from throats of patients

Answer 59

lipopolysaccharide is an endotoxin and forms the outer leaflet of the outer membrane of gram-negative bacteria and comprises: - Lipid A - the toxic portion of LPS that is anchored in the outer leaflet of the outer membrane - core (R) antigen - short chain of sugars, some are unique to LPS - somatic (O) antigen - a highly antigenic repeating chain of oligosaccharides

Answer 60

the toxic portion of LPS that is anchored in the outer leaflet of the outer membrane

Answer 61

short chain of sugars, some are unique to LPS

Answer 62

a highly antigenic repeating chain of oligosaccharides

Answer 63

the toxin/effector (protein) needs to travel past two membranes rather than just one

Answer 64

- K antigen (EPS capsule) - H antigen (flagellum) - O (somatic) antigen (LPS)

Answer 65

- Shigella has no H antigen since it does not have flagellum | - Salmonella does have a H antigen since it does have a flagellum

Answer 66

- rods/bacilli - most are motile i.e. have flagella - some are intestinal parasites - are able to grow in anaerobic conditions - MacConkey agar is used to differentiate between lactose and non-lactose fermenting

Answer 67

• commensals - most abundant facultative anaerobe (facultative means is able to i.e. is able to respire anaerobic, but not only anaerobically, can respire aerobically too) • they have flagella • there are many serotypes/strains • they all share a common ‘core’ genome

Answer 68

- wound infections (surgical) - Urinary Tract Infections (UTIs) - also known as cystitis, 75%-80% female UTIs are from catheterisation - gastroenteritis in children and adults - travellers’ diarrhoea - bacteraemia - the presence of bacteria in the blood - meningitis in infants - rare in the UK

Answer 69

* pathogenic E.coli contains blocks of genes that are not present in commensal E.coli (that live in the gut) * many pathogenic E.coli have ‘acquired’ pathogenicity from other bacteria by ‘mating’ and acquiring pathogenic blocks of genes

Answer 70

- strain is called enterotoxigenic (ET) E.coli (ETEC) - has pilli which enable it to adhere to the tissue of the small intestine - when it binds to the tissue it releases a labile toxin that alters the role of the Gs protein on the GI cell surface meaning it can no longer stimulate adenyl cyclase resulting in more Cl- being released into the GI lumen - this results in water following, resulting in diarrhoea

Answer 71

- S. dysenteriae - S. flexneri - S. boydii - S. sonnei (commonest cause)

Answer 72

all four species cause damage to the intestinal mucosa that result in: - acute infection of the large intestine - painful diarrhoea often with blood and mucus in the stools

Answer 73

the infective dose is just 100 bacteria thus extremely easy to be infected

Answer 74

spread from person-to-person or via contaminated water or food

Answer 75

• these are found in the gut-associated lymphoid tissue (GALT) of the Peyer’s patches and in the mucosa- associated lymphoid tissue (MALT) • these cells initiate mucosal immunity responses and allow for the transport of microbes across the epithelial cell layer from the gut lumen where interactions with immune cells can take place

Answer 76

- bacteria are acid-tolerant so can survive and pass through the stomach - bacteria target microfold (M) cells - shigella induce their own uptake by M-cells, they then cross the epithelial cell layer where they are engulfed by macrophages - however, once engulfed they induce the apoptosis of the macrophages resulting in the release of damaging free radicals resulting in an inflammatory response and cell damage - eventually the bacteria will be destroyed by neutrophils

Answer 77

shiga toxin

Answer 78

some shigella bacteria also release a shiga toxin which disrupts protein synthesis resulting in necrosis: • this toxin targets the kidney resulting in haemolytic uraemic syndrome which can lead to death • shiga toxin is also produced by some E.coli e.g. EHEC

Answer 79

- S.enterica - responsible for salmonellosis (any infection caused with salmonella) - S.bongori - rare, results from reptile contact

Answer 80

- gastroenteritis - enteric fever; typhoid - bacteraemia

Answer 81

* frequent cause of food poisoning from milk and poultry * 6-36 hour incubation * resolves in a week * localised infection

Answer 82

* systemic disease * caused by Salmonella typhi and Salmonella paratyphi * spread is faecal-oral * results in fever, headache, dry cough * splenomegaly and hepatomegaly * diarrhoea may develop

Answer 83

Salmonella typhi and Salmonella paratyphi

Answer 84

faecal-oral

Answer 85

presence of bacteria in the blood - uncommon

Answer 86

- ingestion of contaminated food/water - has a high infective dose - need to ingest a significant amount for infection - Salmonella mediates its endocytosis across the gut lumen

Answer 87

• bacteria presence results in chemokine release and neutrophil recruitment • this results in neutrophil-induced tissue injury due to the inflammatory response • there is fluid and electrolyte loss due to cell damage resulting in diarrhoea • eventual inflammation/necrosis of gut mucose

Answer 88

• migrates to the basolateral membrane of cells in the intestinal lumen - Peyers patch where it results in inflammation and ulceration - diarrhoea • however, initially there is little damage to the gut mucosa • bacteria is then engulfed and survives then spreads systemically via the lymph nodes • then enters bloodstream via the thoracic duct and then multiplies in the macrophages of the liver, spleen and bone marrow resulting in septicaemia which results in massive fever • then spreads to the gall bladder from the liver where person can be in a carrier state from 1 year to the rest of their life

Answer 89

- opportunistic - causes different nosocomial (hospital acquired) infections: • pneumonia • bloodstream infections • wound or surgical site infections • meningitis

Answer 90

- facultative anaerobe - curved rods/bacilli with single polar flagellum - results in cholera - the most severe diarrhoeal disease

Answer 91

faecal-oral route - faecal contaminated water and uncooked shellfish

Answer 92

high infective dose is required since its sensitive to acid i.e. acid in stomach - requires many to get past the stomach

Answer 93

5 hours (multiplies in small intestine)

Answer 94

- results in voluminous watery (rice-water) stools i.e. secretory diarrhoea - can lose 20 litre/day plus electrolytes, this results in: • dehydration and subsequent death • 60% mortality - there is no blood or fever since there is no invasion or damage to mucosa

Answer 95

80% treated with oral rehydration

Answer 96

* pilli - required for colonisation | * Cholera toxin - acts in same way as E.coli labile toxin

Answer 97

- results in uncontrolled cyclic AMP production - which results in the activation of protein kinases - which causes the modification of ion transporter activity causing the loss of Cl- & Na+ resulting in massive H2O loss

Answer 98

- motile - single polar flagellum - opportunistic (serious cause of nosocomial infections) - multiple antibiotic resistance

Answer 99

- burn/surgical wounds - UTIs (catheters) - keratitis (inflammation of cornea)

Answer 100

neutropenic (low on neutrophils) patients (leukaemia, chemotherapy, AIDS)

Answer 101

nosocomial pneumonia

Answer 102

cystic fibrosis

Answer 103

- have poor functioning Cl- transporters meaning they have dehydrated lung mucus which is the perfect environment for bacteria to grow - virtually impossible to remove pseudomonas in cystic fibrosis patient since antibiotic resistant

Answer 104

- exclusively human parasite - nasopharyngeal carriage in 25-80% population - fastidious (specific requirement for survival) - non-motile

Answer 105

young children and adult smokers

Answer 106

* important cause of meningitis, when it crosses the blood-brain barrier (less than 5yrs) and bronchopneumonia * epiglottitis, sinusitis, otitis media (ear infection) * bacteraemia * cystic fibrosis and COPD lung infections

Answer 107

- specific requirement for survival • will not grow on blood agar which supports growth of many other fastidious bacteria - since it cannot access haem in this form • will only grow on chocolate agar: - blood agar which has been heated to 80 degrees to allow the release of haem by red blood cells

Answer 108

blood agar which has been heated to 80 degrees to allow the release of haem by red blood cells

Answer 109

• pilli: adherence to epithelial cells and mucin • capsule: - commensals and respiratory tract pathogens are non-capsulate - invasive strains are capsulate (can penetrate the nasopharyngeal epithelium) • lipopolysaccharide (LPS) endotoxin - results in inflammation

Answer 110

* pertussis is whooping cough * short (sometimes oval) rods/bacilli * highly contagious with a low infect dose

Answer 111

aerosol transmission

Answer 112

• adhere to the ciliated epithelia of the upper respiratory tract/trachea • non-specific flu-like symptoms followed by paroxysmal coughing (cough followed by inhalation resulting in whooping sound) • can lead to sub-conjunctival haemorrhage

Answer 113

• non-flagellated diplococci (go around in pairs) • present in polymorphonuclear lymphocytes of CSF or urethral discharge during infection

Answer 114

N. meningitidis | N. gonorrhoeae

Answer 115

- present in the nasopharynx of 5-10% of the population (asymptomatic) - person-person aerosol transmission (university or barracks)

Answer 116

crosses the nasopharyngeal epithelium and enters the bloodstream in a small proportion of colonised individuals: - asymptomatic bacteraemia (if low numbers of bacteria) or septicaemia if high - meningitis - the colonisation of the subarachnoid space after crossing the blood-brain barrier - there is a very high risk of mortality in the septicaemic form if not treated

Answer 117

• capsule is major virulence determinant: - non-capsulated is only found in the nasopharynx - capsule is anti-phagocytic • pilli on bacteria promote colonisation and cell invasion • lipopolysaccharide results in cytokine cascade and inflammatory response which can lead to sepsis

Answer 118

capsule is major virulence determinant: - non-capsulated is only found in the nasopharynx - capsule is anti-phagocytic

Answer 119

pilli on bacteria promote colonisation and cell invasion

Answer 120

LPS results in cytokine cascade and inflammatory response which can lead to sepsis

Answer 121

- not a commensal but can be asymptomatic (30% of infected females) - person to person only - non-capsulated unlike N.meningitis

Answer 122

it's an STD resulting in: • urethritis with additional infection of female genitalia • can lead to infection of the fallopian tubes if infection ascends

Answer 123

C. jejuni and C. coli

Answer 124

``` • spiral rods/bacilli • most common cause of food poisoning in UK and US: - undercooked poultry e.g. BBQ - unpasteurised milk • has a low infective dose ```

Answer 125

Campylobacter - undercooked poultry e.g. BBQ - unpasteurised milk

Answer 126

* results in mild-sever diarrhoea often with blood - usually self-limiting within a week * Campylobacter shed in faeces for around 3 weeks

Answer 127

invasins and cytolethal distending toxin (CDT)

Answer 128

* invades ileal and colonic epithelial cells | * resulting in local acute inflammatory response i.e. tissue damage

Answer 129

arrests the cell cycle meaning target cells swell and lyse

Answer 130

* require CO2 (microaerophilic) | * spiral shaped

Answer 131

present in 50% of global population but only a fraction will develop the disease

Answer 132

* major role in gastritis and peptic ulcer disease | * implicated in gastric adenocarcinoma

Answer 133

urease - hydrolyses urea to generate ammonia to act as a buffer to gastric acid

Answer 134

very small and non-motile

Answer 135

- elementary bodies; dormant | - reticulate bodies; metabolically active and fragile

Answer 136

- infectious - enter cell through endocytosis - prevent phagosome fusion - dormant

Answer 137

- replicative - non-infectious - metabolically active - fragile

Answer 138

Chlamydia trachomatis

Answer 139

* can spread to the uterus and ovaries resulting in pelvic inflammatory disease * usually asymptomatic

Answer 140

* can cause conjunctivitis (STD) | * can cause trachoma - blindness that is spread via flies

Answer 141

- respiratory tract - urinary tract - GI tract - meningitis - STIs - wound infections

Answer 142

* Bordetella pertussis | * Haemophilus influenzae

Answer 143

* some E.coli strains | * Klebsiella pneumoniae

Answer 144

* Vibrio cholera * Shigella dysenteriae * some E.coli strains * Campylobacter jejuni * Helicobacter pylori

Answer 145

* Neisseria meningitidis | * Haemophilus influenzae

Answer 146

* Klebsiella pneumoniae | * Chlamydia trachomatis

Answer 147

* Pseudomonas aeruginosa | * some E.coli strains

Answer 148

- eukaryotic - have a nuclear membrane - chitinous cell wall - heterotrophic: get nutrients from what they are living on - move by means of growth or spore release

Answer 149

type of fungi that is a small single celled organisms that divide by budding

Answer 150

type of fungi that form multicellular hyphae and spores

Answer 151

some fungi exist as both yeasts and moulds switching between the two when conditions suit - these are dimorphic fungi

Answer 152

Coccidioides immitis

Answer 153

* grow as mould at ambient temperature | * convert to yeast form at body temperature after inhalation

Answer 154

- only a few fungal forms can actually infect humans - fungi have an inability to grow at 37 degrees (body temperature) - fungi also cannot evade the adaptive/innate immune response

Answer 155

- enormous since most will have had at least one in lifetime e.g nappy rash, tinea pedis (athletes foot) and fungal asthma - however life-threatening fungal infection is rare in healthy hosts

Answer 156

* Candida line infections * Pneumocystis * invasive aspergillosis

Answer 157

intra-abdominal infections

Answer 158

- fungal asthma | - travel associated fungal infections e.g. dimorphic fungi

Answer 159

to achieve inhibitory levels of the agent at the site of the infection without host cell toxicity

Answer 160

relies on identifying molecules with selective toxicity for organism targets

Answer 161

* target does not exist in humans * target is significantly different to human analogue * drug is concentrated in organism cell with respect to humans * organism has an increased permeability to the compound * human cells are ‘rescued’ from toxicity by alternative metabolic pathways

Answer 162

in general the concept of selective toxicity is much harder to achieved for fungi as opposed to bacteria due to the fact that fungi are eukaryotic, and so are human cells thus they are more similar and thus harder to differentiate

Answer 163

* DNA/RNA synthesis and protein synthesis * similar to mammalian * drugs targeting these: Flucytosine

Answer 164

* mannoproteins * B1,3 glucan * B1,6 glucan * chitin * does not exist in humans * drugs targeting these: Echinocandins

Answer 165

* containing ergosterol * human cell membrane contains cholesterol NOT ergosterol * drugs targeting these: Amphotericin, Azoles and Terbinafine

Answer 166

ergosterol

Answer 167

a compound that is able to act as a base and an acid

Answer 168

amphotericin B

Answer 169

- drugs used to treat fungal infections - e.g. Amphotericin B - cause pore formation in ergosterol containing membranes - fungicidal

Answer 170

it has 10 times lower affinity for cholesterol in mammalian | membranes

Answer 171

- nephrotoxicity - dose dependent; usually reversible - distal renal tubular acidosis (hypokalaemia) - can cause hyperkalaemia if infused rapidly resulting in cellular damage - also causes infusion related; chills/rigors/hypotension and acute anaphylactoid reactions

Answer 172

* causes the reversible inhibition of squalene epoxidase (an enzyme required for growth of the fungi) * it's a fungicidal

Answer 173

Terbinafine

Answer 174

* it is well absorbed but undergoes extensive first pass metabolism resulting in a bioavailability of only 45% * distributes extensively to poorly perfused sites such as the skin and nail beds (common sites of fungal infection) * primarily used against Candida and Aspergillus

Answer 175

* well tolerated and only results in taste disturbance and deranged liver function tests (LFT) * it does result in increased CYP450 metabolism but this is by multiple enzymes and is minimally inhibitory

Answer 176

* dose-dependent inhibitors of 14a-sterol demethylase - an important intermediate in the pathway of cholesterol (human) and ergosterol (fungi) production * it's a fungistatic

Answer 177

• clotrimazole and ketoconazole is active against Candida • fluconazole is active against Cryptococcus • itraconazole is active against Aspergillus and dimorphics such as Coccidiodes and Sporothrix

Answer 178

clotrimazole and ketoconazole

Answer 179

fluconazole

Answer 180

itraconazole

Answer 181

- relatively safe - all associated with transaminitis (elevated transaminases in liver) and GI side effects - rare to cause severe hepatitis - alopecia with long term fluconazole - GI symptoms are more pronounced with itraconazole: • nausea, abdominal pain and diarrhoea • rare life threatening liver failure

Answer 182

* hydrophilic and excreted unchanged | * less significant interactions with: warfarin, anxiolytics and calcineurin inhibitors

Answer 183

``` • a potent CYP3A4 inhibitor • interactions with: - less significant interactions with: warfarin, anxiolytics and calcineurin inhibitors - steroids - statins ```

Answer 184

- multiple mechanism in Candida | - fluconazole and voriconazole most affected

Answer 185

* inhibit 1,3 B glucan synthase - interferes with fungal cell wall synthesis * is fungicidal to susceptible yeasts * is fungistatic to moulds * has activity against mould but not yeast forms of dimorphics

Answer 186

some fungi genera that do not have large amounts of 1,3 B glucan in their cell wall are intrinsically resistant to this drug class: - Crytococcus - Zygomycetes - Trichosporon - limited activity against Scedosporium

Answer 187

* has poor oral bioavailability thus IV only * has poor penetration into the CSF, eye and urine * few drug interactions

Answer 188

- rare type-1 hypersensitivity - hepatotoxicity - hypokalaemia

Answer 189

- Amphotericin B, Nystatin - binds to sterols and destabilises cell membrane - used in systemic and topical disease

Answer 190

- clotrimazole, miconazole, ketoconazole, fluconazole, itraconazole, voriconazole, posaconazole - inhibits ergosterol biosynthesis - used in topical and systemic disease

Answer 191

- terbinafine - inhibit ergosterol biosynthesis - used in superficial infections, including onychomycosis

Answer 192

- caspofungin, anidulafungin, micafungin - inhibit the formation of cell wall glucan - used in systemic disease

Answer 193

- 5-fluorocytosine - inhibit DNA and RNA synthesis - used in systemic disease

Answer 194

- griseofulvin - inhibits microtubule assembly - used in topical disease

Answer 195

- blood cultures are only half as sensitive for fungi as for bacteria - it's better to pick-up from tissue/fluids: • if cultured properly • if these samples can be obtained

Answer 196

- pretty much all Candida are sensitive to Echinocandins | - pretty much all Candida are sensitive to Amphotericin B

Answer 197

- the cell wall component of many fungi including common ascomycetous pathogens and pneumocystis - released into serum during invasive infection

Answer 198

fungal nail infection; very common

Answer 199

- caused by dermatophyte moulds: • grow best at about 30 degrees - Trichophyton rubrum is the most common cause

Answer 200

microscopy is most specific, but 30% of the culture is negative

Answer 201

* psoriasis * lichen planus * trauma * eczema * malignant melanoma

Answer 202

- results of sampling can be confusing - limited treatment options: • topical amorolfine • systemic itraconazole or terbinafine - treatment takes ages - high failure rate with all therapies

Answer 203

- infection/colonisation of health people is frequent and occurs early in life - disease develops only with moderate-severe immunocompromised especially in HIV, transplant and steroids - think pneumocystis when a patient has hypoxia that is more severe than the chest x-ray would suggest - especially with gradual onset or risk factors

Answer 204

* Co-trimoxazole * Clindamycin * Pentamidine * Trimetrexate

Answer 205

- M. tuberculosis; tuberculosis - M. leprae; leprosy - M.avium complex (MAC); disseminated infections in AIDS, infections in patients with chronic lung disease - M. kansasii - chronic lung infection - M. marinum - fish tank granuloma - M. ulcerans - Buruli ulcer

Answer 206

Mycobacterium tuberculosis

Answer 207

M. avium complex

Answer 208

M. kansasii

Answer 209

M. marinum

Answer 210

M. ulcerans

Answer 211

- aerobic - have resistance to destaining by acid and alcohol - may cause meningitis - tuberculosis meningitis - can withstand phagolysosomal killing - non-spore formin - non-motile bacillus/rods - high cell wall content of high molecular weight lipids - slow growing - cell wall key components

Answer 212

* weakly gram-positive or colourless - it difficult to stain mycobacteria since they have a thick cell wall that doesn't take up stain easily * cell wall contains lipoarabinomannan * survives inside macrophages, even in low pH environments * mycolic acids and liporabinomannan - make up strong waxy cell wall that is hard for the immune system to target/damage

Answer 213

* M. tuberculosis generation time 15-20 hours compared to 1 hour for common bacterial pathogens * slow growth means its difficult for antibiotics to target the division phase of the mycobacteria

Answer 214

- bacteria should be found in all people with disease - bacteria should be isolated from the infected lesions in people with the disease - a pure culture inoculated into a susceptible person should produce symptoms of the disease - the same bacteria should be isolated from the intentionally infected individual

Answer 215

- high lipid content with mycolic acids in cell wall makes Mycobacteria resistant to Gram stain - slightly curved, beaded bacilli/rods

Answer 216

red/pink (positive for acid-fast)

Answer 217

- nucleic acid amplification using PCR - produces rapid result for mycobacterium tuberculosis - highly sensitive and specific test - recommended for the rapid diagnosis in TB endemic countries

Answer 218

- Mycobacteria are acid fast bacilli that are phagocytosed by macrophages and are placed in a phagolysosome within the macrophage - the bacteria has adapted to the intracellular environment and aims to withstand phagolysosomal killing and escape to the cytosol - primarily through the presence of their thick waxy cell wall - the host aims to kill the mycobacterium using microbicidal molecules - acidification aids digestion and degradation by proteases of the mycobacteria which results in the generation of antigens for presentation to T-cells

Answer 219

- effective immunity requires CD4 T-cells which generate interferon gamma and this helps activate intracellular killing by macrophages - IL-12 release by macrophages further stimulates the generation of T helper cells and interferon gamma release - genetic defects in interferon gamma or IL-12 receptors or elements of their signalling pathways result in susceptibility to mycobacterial infection

Answer 220

granuloma are lesions the arise in a response that tries to contain mycobacteria (but also occur in other infections and non-infectious processes): • highly stimulated macrophages become epithelioid cells • some macrophages fuse with each other to form giant multinucleate cells “Langhans giant cells” • T cells including cytotoxic CD8 T-cells infiltrate the granuloma

Answer 221

a granuloma prevents nutrients from entering - thereby starving the mycobacteria: • TB will go into a dormant state when inside the granuloma • can reactivate at some point in the future when conditions are better

Answer 222

the highly immunogenic nature of mycobacterial lipids stimulate T-cell responses 3-9 weeks after exposure to M. tuberculosis

Answer 223

macrophage killing of mycobacteria, containment of | infection, formation of a tissue granuloma

Answer 224

hypersensitivity reactions (type 4) with skin lesions, eye lesions and swelling of joints

Answer 225

- this reactivity can be measured in the tuberculin skin test where intradermal injection of purified protein derivatives induce skin swelling and redness - it can also be measured in interferon gamma release assays

Answer 226

* use antigens specific to M. tuberculosis e.g. ESAT-60 and CFP10 to distinguish between this and BCG vaccine or environmental mycobacteria * IGRAs demonstrate exposure to M.tuberculosis but not active infection

Answer 227

- slowly replicating bacteria so need prolonged treatment - 6 months of antimicrobials - there are different populations of mycobacteria in particular locations intracellularly and extracellularly or in environments of differing pH - resistance may emerge on treatment so use multi-drug combinations to ensure target all populations and mutants - compliance is essential; directly observed treatment used for many patient groups to ensure success

Answer 228

* Isoniazid (INH), Rifampicin (RIF), Pyrazinamide (PZA), Ethambutol (ETH) for two months * Isoniazid and rifampicin for further 4 months

Answer 229

* fluroquinolones * injectable agents such as; streptomycin, cyclosporine and capreomycin * prothionamide

Answer 230

* hepatotoxicity - Isoniazid, rifampicin, pyrazinamide * peripheral neuropathy with isoniazid - give vitamin B6 to protect against this * optic neuritis - ethambutol

Answer 231

* bacilli settle in apex (top part near shoulders) and granuloma forms * bacilli taken in lymphatics to hilar lymph nodes * in apex of lungs there is more air and less blood supply thus fewer defending white cells to fight off infection

Answer 232

granuloma + lymphatics + lymph nodes

Answer 233

* cell mediated immune (CMI) response from T-cells | * primary infection is contained but CMI persists

Answer 234

* no clinical disease (normal chest x-ray) | * detectable CMI to TB on tuberculin skin test of IGRA

Answer 235

* could occur immediately following primary disease (post-primary) or after latent reactivation * cell mediated immune (CMI) response from T-cells * necrosis in lesion * caseous material coughed up leaving cavity * TB may spread in lung causing other lesions * CMI and caseation in lesion results in cavity

Answer 236

bacilli can spread from apex to hilar lymph nodes and then elsewhere

Answer 237

- TB meningitis - miliary TB (widespread dissemination and tiny spotted lesions all over lungs and elsewhere) - pleural TB - bone and joint TB - genitourinary TB

Answer 238

- nematodes (roundworms) - trematodes (flatworms, flukes) - cestodes (tapeworms)

Answer 239

* intestinal * Larva migrans * tissue (filaria)

Answer 240

* blood * liver * lung * intestinal

Answer 241

* non-invasive | * invasive

Answer 242

- rare in UK - most cases are imported - adult worms cannot usually reproduce without a period of development outside the body - worm cannot replicate inside body, so if it cannot get out it will eventually die - thus, although they usually produce innumerable larvae or eggs (which may themselves cause disease), the total worm burden cannot increase without constant re-exposure to infection

Answer 243

the interval between infection and the appearance of eggs in the stool

Answer 244

* single-celled eukaryotic organisms with a definitive nucleus * eaten by invertebrates * important parasitic and symbiotic relationships

Answer 245

consumers of bacteria, algae and microfungi

Answer 246

all eat food by phagocytosis and then digest it in intracellular vacuoles

Answer 247

in aqueous environments and the soil

Answer 248

- type of protozoa - flagellum as main locomotory organelle - usually reproduce by binary fission

Answer 249

- intestinal flagellates - haemoflagellates - other body sites

Answer 250

Giardia lamblia

Answer 251

- 7-day business trip to Delhi 2 months ago - loose stools on last day of stay in India - ongoing offensive diarrhoea daily since return to UK - flatulence, abdominal cramps

Answer 252

Trypanosoma spp.

Answer 253

- also known as ‘sleeping sickness’ - bitten on arm by insect; lesion developed 2 weeks later > self-resolved - 2 years later he gets fever, lethargy and myalgia - excessive weight loss - personality change - irritability - increasing daytime tiredness - coma - the West African strain is more severe compared to the more endemic East African strain

Answer 254

- amoebae | - move by means of flowing cytoplasm and production of pseudopodia

Answer 255

Entanomoeba histolytica

Answer 256

- 2-month visit to rural Botswana - bloody diarrhoea - on return to UK, increasing right upper quadrant pain - CT shows liver abscess

Answer 257

- sporozoans - no locomotory extensions - all species are parasitic - most are intracellular parasites - reproduce by multiple fission

Answer 258

- malaria: Plasmodium spp. | - other: Cryptosporidium spp. and Toxoplasma gondii

Answer 259

- recent HIV positive diagnosis: CD4 count: 70 (below 450 = low and below 100 = high risk of AIDs) - 2-week history of progressive left sided weakness - headaches and visual disturbances - commonly presents when people are immunosuppressed e.g. HIV/AIDs or cancer on chemotherapy

Answer 260

- ciliates - very large group - have cilia that beat rhythmically at some stage in lifecycle - two types of nuclei (macronucleus and micronucleus)

Answer 261

Balantidium coli - presents mainly in those who are immunocompromised - causes severe diarrhoea and/or ulceration of colon

Answer 262

* very small * production of resistant spores * causes diarrhoea in immunocompromised

Answer 263

Enterocytozoon bieneusi

Answer 264

- mastigophora (flagellates) - sarcodina (ameobae) - apicomplexa (sporozoans) - ciliophora (ciliates) - microsporidia

Answer 265

protozoan infection caused by Plasmodia spp..

Answer 266

``` 4 species cause human disease: • P. falciparum (most common) • P. ovale • P. vivax • P. malariae ```

Answer 267

transmitted by the bite of the female anopheles mosquito

Answer 268

* 300-500 million cases per year (80% Africa) * 700,000 - 2.7 million deaths a year (more than 90% African) * cause of 50% of fever in African children under 5 * 50% of world population at risk

Answer 269

- increasing resistance of parasite to antimalarials - increased resistance of mosquito to insecticides - ecological and climate changes - means mosquitoes can be found in more countries - increased travel to endemic areas

Answer 270

female anopheles mosquito; mainly bites at night

Answer 271

worldwide distribution

Answer 272

* infection is acquired during feeding from infected human | * mosquito is infected for life

Answer 273

* night biting * mainly bites indoors * lifecycle depends on water

Answer 274

* plasmodia lifecycle has stages in human and mosquito host | * variation in lifecycle between different Plasmodia spp. results in different clinical manifestations

Answer 275

the female anopheles mosquito becomes infected after taking a blood meal containing gametocytes, the sexual form of the malarial parasite

Answer 276

the developmental cycle in the mosquito usually takes 7-20 days (depending on temperature) culminating in the migration of infective sporozoites to the insect’s salivary glands

Answer 277

1. infection of parasite (female anophales mosquito) 2. multiplication in liver 3. invasion and multiplication in RBCs 4. formation of gametocytes 5. completion of gametogony 6. migration of sporozoites to mosquito salivary gland

Answer 278

* the sporozoites are inoculated into a new human host and those not destroyed by the immune system are rapidly taken up by the liver * here they multiply inside hepatocytes as merozoites; this is the pre-erythrocytic (or hepatic) sporogeny

Answer 279

* the sporozoites are inoculated into a new human host and those not destroyed by the immune system are rapidly taken up by the liver * here they multiply inside hepatocytes as merozoites; this is the pre-erythrocytic (or hepatic) sporogeny

Answer 280

after a few days, the infected hepatocytes rupture, releasing merozoites into the blood, from where they are rapidly taken up by erythrocytes

Answer 281

* in the case of P. vivax and P. ovale, a few parasites remain dormant in the liver as hypnozoites - these may reactivate at any time subsequently, causing relapsing infection - this is why its important to ask a 2 year travel history to counter P.vivax and P.ovale * can remember by OVO - Ovale Vivax Overstay * also note due to the dormancy the hypnozoites will not be eradicated by conventional antimalarials

Answer 282

Ovale Vivax Overstay - these parasites can become hypnozoites and remain dormant in the liver - won't be eradicated by conventional antimalarials

Answer 283

• inside the red cells, the parasites again multiply, changing from merozoites to trophozoites to schizonts and finally appearing as 8-24 new merozoites • the erythrocyte ruptures, releasing the merozoites to infect further cells this is erythrocytic schizogony

Answer 284

• inside the red cells, the parasites again multiply, changing from merozoites to trophozoites to schizonts and finally appearing as 8-24 new merozoites • the erythrocyte ruptures, releasing the merozoites to infect further cells

Answer 285

* each cycle of this process, which is called erythrocytic schizogony, takes about 48 hours in P. falciparum, P. vivax and P.ovale disease * whereas in P. malariae it takes 72 hours

Answer 286

mainly reticulocytes and young erythrocytes

Answer 287

tends to attack older cells

Answer 288

parasitises any stage of erythrocyte

Answer 289

trophozoites or gametocytes

Answer 290

- develop from merozoites | - not released from red cells until they are taken up by a feeding mosquito to complete the life cycle

Answer 291

sporozoites -> merozoites -> trophozoites -> schizonts -> merozoites

Answer 292

pathology is related to anaemia, cytokine release and in the case of P. falciparum, widespread organ damage due to impaired microcirculation

Answer 293

- haemolysis of infected red cells - haemolysis of non-infected red cells (Blackwater fever - when malaria is left to go untreated; results in dark coloured urine) - splenomegaly - folate depletion

Answer 294

- red cells contains schizonts adhere to the lining of capillaries in the brain, kidneys, gut, liver and other organs - as well as causing mechanical obstruction, these schizonts can rupture, releasing toxins and stimulating further cytokine release

Answer 295

10-21 days

Answer 296

``` • very varied • fever is common (but not always present) • other common features: - chills and sweats - headache - myalgia - fatigue - nausea and vomiting - diarrhoea ```

Answer 297

in any febrile individual who has resided in or travelled to an endemic area

Answer 298

- illness is usually relatively mild - although P. vivax can occasionally cause severe disease - anaemia develops slowly and there may be tender hepatosplenomegaly - spontaneous recovery usually occurs within 2-6 weeks but hypnozoites in the liver can cause relapses for many years after infection - repeated infections often cause chronic ill health due to anaemia and hyper-reactive splenomegaly

Answer 299

- this causes a relatively mild illness but tends to run a more chronic course - parasitaemia (parasites in blood) may persist for years, with or without symptoms - in children, P.malariae infection is associated with glomerulonephritis and nephrotic syndrome

Answer 300

P. falciparum

Answer 301

- causes a self-limiting illness similar to the other types of malaria - it may cause serious complications and the vast majority of deaths are due to P. falciparum - patients can deteriorate rapidly, and children in particular progress from reasonable health to coma and death within hours - a high parasitaemia (more than 1% of red cells infected) is an indicator of severe disease - cerebral - blackwater fever

Answer 302

- shock | - hypotensive (<80 systolic and Gram-negative septicaemia)

Answer 303

- hypoglycaemia (<2mmol/L) | - metabolic acidosis

Answer 304

- prostration | - cerebral malaria

Answer 305

retinal haemorrhages

Answer 306

- tachypnoea | - acute respiratory distress syndrome

Answer 307

- severe anaemia (haemolysis and dyserythropoiesis) - DIC - bleeding

Answer 308

- haemoglobuinuria - oliguria - uraemia

Answer 309

- diarrhoea - jaundice - splenic rupture

Answer 310

``` - cerebral malaria is marked by diminished consciousness, confusion and convulsions progressing to coma and death - due to the reduced brain perfusion caused by schizonts adhering to the endothelial cells of capillaries = hypoxia to brain ```

Answer 311

widespread intravascular haemolysis, affecting both parasitised and unparasitised red cells, giving rise to dark urine

Answer 312

* coma * acute respiratory distress syndrome (ARDS) * anaemia * jaundice * hepatosplenomegaly * hypoglycaemia - since parasites eat up glucose (pregnant women especially susceptible) * blackwater fever * renal failure due to hypovolaemia and microvascular blockade due to the schizonts * shock secondary to bacterial sepsis

Answer 313

* non-specific; they stop crying, playing and eating * tachypnoea - rapid breathing * anaemia * hypoglycaemia * cerebral malaria * raised intracranial pressure * convulsions (60-80%) * rule out meningitis

Answer 314

- anaemia - low platelets - hyperbilirubinaemia - mildly raised transaminases (ALT, AST)

Answer 315

- thick and thin | - do films at least 12hrs apart to check for presence

Answer 316

• sensitive but low resolution (difficult to interpret and speciate the parasite but has a higher yield) • tells you is malaria is present

Answer 317

• can identify morphological features and quantification of parasitaemia • tells you type and parasite count, above 2% = severe • trophozoite most commonly used

Answer 318

3 separate films should be examined before malaria is declared unlikely

Answer 319

- extreme weakness (e.g. inability to walk or sit) - impaired consciousness - hypoglycaemia - parasite count greater than 2% - spontaneous bleeding/disseminated intravascular coagulation - haemoglobinuria - renal impairment or electrolyte/acid-base disturbance (pH less than 7.3) - pulmonary oedema or adult respiratory distress syndrome - shock

Answer 320

* IV artesunate (gold standard) | * or IV quinine (second best since it causes hypoglycaemia so monitor sugar levels)

Answer 321

- oral riamet - or oral quinine - add doxycycline as 2nd agent to treat undiscovered/untreated malaria

Answer 322

oral chloroquine

Answer 323

- primaquine for hypnozoite clearance | - check G6PD (G6PD deficiency) and pregnancy status since not suitable for these individuals

Answer 324

* most common imported tropical disease in UK * around 75% are falciparum * mixed infections * commonly presents ‘atypically’ e.g no fever * in pregnancy is severe

Answer 325

- sickle cell trait gives protection against malaria - Glucose-6-phosphate dehydrogenase deficiency (G6PD) - G6PD is an enzyme that is essential for assuring the normal lifespan for red blood cells, deficiency results in the sudden destruction of red blood cells and can lead to haemolytic anaemia - malaria parasites cannot survive in these red cells - Thalaessaemias confer protection against malaria

Answer 326

- recurrent infection can result in semi-immunity but this is lost if not reinfected after a couple of years - maternal transmission of antibodies across the placenta, but this diminishes over time

Answer 327

- dengue and viruses - malaria and protozoa - trypanosomes and leishmaniasis - helminths/worms

Answer 328

- hookworm, ascaris | - Buruli Ulcer

Answer 329

- amoebae, giardia | - typhoid, bacteria

Answer 330

- the most common arthropod-borne viral infection in humans; over 100 million cases occur every year in the tropics, with over 10,000 deaths from dengue haemorrhagic fever - disease is endemic in all tropical regions including norther Australia, most South-east Asian countries, tropical Africa and the Middle East and Caribbean countries - cases of dengue are also imported into the continental USA and Europe (e.g. Italy) via tourists returning from endemic countries

Answer 331

dengue fever

Answer 332

flavovirus

Answer 333

transmitted by the Aedes mosquito which is daytime-biting - breeds in standing water in refuse dumps in inner cities

Answer 334

- humans are infective during the first 3 days of illness - mosquitoes become infective about 2 weeks after feeding on an infected individual and remain so for life

Answer 335

incubation is 5-6 days following the mosquito bite

Answer 336

* fever * malaise * headache * facial flushing * retrobulbar pain (behind eyes) * severe backache

Answer 337

- fever subsides after 3-4 days, the temperature returns to normal for a couple of days and then the fever RETURNS, together with the above features but milder - severe fatigue, a feeling of being unwell and depression are common several weeks after the fever has subsided

Answer 338

a severe form of dengue fever and believed to be the result of two or more sequential infections with different dengue serotypes

Answer 339

* capillary leak syndrome * thrombocytopenia (low platelet count) * haemorrhage * hypotension * shock

Answer 340

characteristically a disease of children, occurring most | commonly in South-east Asia

Answer 341

mild start, often with symptoms of an upper respiratory tract infection

Answer 342

* shock * haemorrhage into the skin and ear * bleeding from nose (epistaxis) * haematemesis (vomiting blood) * meleana (bloody stools) * all collectively known as dengue shock syndrome

Answer 343

* isolation of dengue virus by tissue culture, or detection of viral RNA by PCR in sera obtained during the first few days of illness - diagnostic * detection of virus-specific IgM antibodies, or of rising IgG titres in sequential serum samples

Answer 344

* supportive with analgesics and adequate fluid replacement | * in DHF, blood transfusion may be necessary as well as intensive care support

Answer 345

* about 20-220nm diameter * only visualised by electron microscopy * in comparison staphylococci bacteria are about 1 micrometer in diameter

Answer 346

grow only inside living cells

Answer 347

when diagnosing viral infections samples do not need to come from sterile sites since there are no commensal viruses to confuse with

Answer 348

posses only one type of nucleic acid, RNA or DNA

Answer 349

- posses only one type of nucleic acid, RNA or DNA - no cell wall structure but have an outer protein coat surrounded in some viruses by a lipid envelope (contains viral proteins and lipids) - essentially inert outside the host cell, but carry proteins that function as enzymes inside the cell - proteins on virus surface allow attachment to complementary receptors on susceptible host cell plasma membrane

Answer 350

takeover protein manufacture in order to replicate itself

Answer 351

1. attachment 2. cell entry 3. interaction with host cells 4. replication 5. assembly 6. release

Answer 352

viral and cell receptors e.g. HIV (gp120 on HIV and CD4 on T cell)

Answer 353

- only the viral ‘core’ which carries the nucleic acid and some associated proteins acting as enzymes for replication and negation of intracellular host defence factors are freed into the host cell cytoplasm - outer protein coat does not enter

Answer 354

- virus uses cell materials (enzymes, amino acids, nucleotides) for their own replication - also need to subvert host cell defences

Answer 355

production of progeny viral nucleic acid and viral proteins in nucleus, cytoplasm or both

Answer 356

- can occur in nucleus e.g. herpesvirus - can occur in cytoplasm e.g. polio virus - can occur in cell membrane e.g. influenza virus

Answer 357

- by bursting open (lysis) of cell e.g. rhinovirus - by ‘leaking’ (exocytosis) from the cell overtime e.g. HIV & influenza virus (2-3 days from upper respiratory tract) - only a few virus particles will enter the host but millions will exit due to replication

Answer 358

- in most viral disease, more than one damage-inducing mechanism operates - some host-derived immunopathological damage occurs in most visual infections

Answer 359

1. damage by direct destruction of host cells e.g. polio, influenza (respiratory cells) and HIV (immune cells 2. damage by modification of host cell structure or function 3. damage involving over-reactivity of the host as a response to infection - immunopathological damage e.g. hep B and C and HIV 4. damage through cell proliferation and cell immortalisation (cancer) e.g. human papillomavirus (HPVs): 5. evasion of both extracellular and intracellular host defences

Answer 360

- polio virus - influenza (respiratory cells) - HIV (immune cells)

Answer 361

- 3 types but type 1 is the most severe - controlled by vaccination, enters body orally then invades and replicates in the gut then travels in the bloodstream and targets the brain where it results in direct brain cell destruction - once infection reaches the brain in unimmunised person it's very difficult to deal with and can result in paralysis - by the time an immune response is in effect, the virus has already caused damage

Answer 362

* physical modification e.g. rotavirus or HIV | * functional modification e.g. rotavirus, respiratory syncytial virus (RSV) and HIV

Answer 363

rotavirus or HIV

Answer 364

rotavirus, respiratory syncytial virus and HIV

Answer 365

1. following ingestion, rotavirus infects epithelial cells of the small intestine, mainly in the jejunum (rotavirus are resistant to acid pH) 2. histologically, there is shortening and atrophy of the villi, flattening of the epithelial cells and stripping of the microvilli - decreasing the surface areas of the small intestine 3. this limits the production of digestive enzymes such as the disaccharides, normally synthesised by the cells of the brush border 4. the patient suffers a malabsorptive state in which dietary nutrients such as sugars are not absorbed by the small intestine 5. this results in hyperosmotic effects causing profuse diarrhoea

Answer 366

- fluid replacement therapy can usually solve the problem - if caught early its easily treatable - if caught late there good by some long term problems

Answer 367

hep B and C, and HIV

Answer 368

- the majority of HBV infection are asymptomatic - both HBV and hepatitis C are spread by blood or sexual contact - following symptomatic HBV infection there are massive antibody and cell mediated immune (CMI) responses that destroy many virally infected hepatocytes - this results in extensive liver damage resulting in jaundice - during acute infection, large numbers of infectious HBV particles are produced - if you recover (most do) then you will be a carrier and 80% will be asymptomatic

Answer 369

blood or sexual contact

Answer 370

in a HBV carrier there is a steady-state between virus | replication in host cells and the host defence responses

Answer 371

- limited but sustained viral replication - natural hepatocyte regeneration - proliferation of hepatocytes due to the oncogenic properties of HBV - liver cell destruction by CD8+ T cells that recognise HBV proteins on the hepatocyte surface as ‘foreign’ - no clinical symptoms but HBV particles circulate in the patients bloodstream

Answer 372

- causes plantar warts | - can result in cancers, particularly those of the cervix

Answer 373

- has no envelope compared to influenza, hepatitis B or C - very small - there are 70-80 different viruses, only type 16 and 18 have oncogenic potential in humans

Answer 374

* HPV 16 and 18 are responsible for cervical carcinoma | * result of HPV infection of supra basal layer in genital tract

Answer 375

• once in the supra basal layer, the virus may partially replicate including transcription and expression of several early viral gene products • at some point the HPV genome may become integrated into the host cell chromosome • following integration, control of viral gene expression by the HPV E2 protein is lost and the HPV E6 and E7 proteins may be expressed • when expressed, the HPV E6 and E7 proteins prevent the operation of two cell growth and proliferation suppressor proteins - Retinoblastoma (Rb) and p53 • excessive cell growth and proliferation occurs and cervical cell carcinoma can result

Answer 376

• following integration, control of viral gene expression by the HPV E2 protein is lost and the HPV E6 and E7 proteins may be expressed • when expressed, the HPV E6 and E7 proteins prevent the operation of two cell growth and proliferation suppressor proteins - Retinoblastoma (Rb) and p53

Answer 377

- virus persistence - virus variability - variation of antigens - persistence or latency - cell to cell spread - antigenic variability - prevention of host cell apoptosis - down regulation of interferon and other intracellular host defence proteins; most viruses do this - interference with host cell antigen processing pathways

Answer 378

- Herpes viruses (survive throughout lifetime) - Hepatitis B and C viruses - measles virus - HIV

Answer 379

- influenza (mutates yearly - a vaccine that works one year will be less effective the next year) - HIV - Hepatitis C virus - rhinovirus

Answer 380

- persistence or latency | - cell to cell spread

Answer 381

- all herpes viruses (HSV- 1 and 2) - Varicella-zoster virus (VZV) - Epstein-barr virus (EBV) - causes glandular fever, remains latent in B cells meaning you carry virus for rest of life and can transmit via oral secretions

Answer 382

- measles virus | - HIV

Answer 383

- influenza type A virus - HIV - Rhinovirus

Answer 384

- Herpes virus - HIV - since host cell defence mechanism is to destroy itself, the virus releases proteins to prevent this and is thus able to continue to replicate

Answer 385

- Herpes virus - Measles virus - HIV

Answer 386

- variation through the formation of ‘quasi-species’ e.g. HIV and hepatitis C virus - variation through gene re-assortment and mutation e.g. Influenza A viruses and HIV - variation through many stable serotypes e.g. rhinoviruses - about 110 different cold viruses

Answer 387

hand hygiene!

Answer 388

- Carbapenemase producing Enterobacteriaceae | - also known as coliforms - standard gut germs

Answer 389

* E.coli * Klebsiella * Serratia * Enterobacter

Answer 390

- colonisers of the large bowel, skin below waist and moist sites - the most common causes of UTI and intra-abdominal infection - occasional respiratory tract infection and skin and soft tissue infection - in the past, the vast majority of these germs were susceptible to the antibiotics that we currently use with gram negative infection

Answer 391

these are the broadest spectrum beta-lactam antibiotics available

Answer 392

they have moved from being rarely used last resort antibiotics to frequently used second-line agents and even first-line therapy for patients with severe sepsis; this is because resistance of gram negatives to other agents like cephalosporins and piperacillin-tazobactam has increased

Answer 393

- hydrolyse carbapenems and other beta-lactams | - confer resistance to the entire class of antibiotic

Answer 394

agents produced by micro-organisms that kill or inhibit the growth of other micro-organisms in high-dilution

Answer 395

penicillin

Answer 396

semi-synthetic derivatives of antimicrobials

Answer 397

antibiotics are molecules that work by binding a target site on a bacteria: - defined as points of biochemical reaction crucial to the survival of the bacterium - the crucial binding site will vary with the antimicrobial class

Answer 398

defined as points of biochemical reaction crucial to the survival of the bacterium

Answer 399

- Beta lactams (penicillins and cephalosporins) glycopeptides - Metronidazole and Rifampicin - Fluroquinolones - Aminoglycosides, Tetracyclines, Macrolides and Chloramphenicol - Sulphonamides and Trimethoprim

Answer 400

these bind to bacterial cell wall and result in the inhibition of cell wall synthesis e.g. penicillin binding proteins on bacteria surface

Answer 401

interfere with nucleic acid synthesis or function

Answer 402

inhibit DNA gyrase (essential for bacterial DNA replication)

Answer 403

inhibit ribosomal activity and protein synthesis

Answer 404

inhibit folate synthesis - required for bacteria to grow since folic acid cannot cross the bacteria cell wall

Answer 405

beta lactams (penicillins and cephalosporins) glycopeptides

Answer 406

metronidazole and rifampicin

Answer 407

fluroquinolones

Answer 408

aminoglycosides, tetracyclines, macrolides and chloramphenicol

Answer 409

sulphonamides and trimethoprim

Answer 410

* prevent the growth of bacteria but not necessarily kill it * however in more than 90% they kill in 18-24 hours * antibiotics that inhibit protein synthesis, DNA replication or metabolism are bacteriostatic

Answer 411

* these agents kill the bacteria * they kill more than 99% in 18-24 hours * antibiotics that generally inhibit cell wall synthesis * useful if there is poor penetration e.g. endocarditis or difficult to treat infections or need to eradicate infection quickly e.g. meningitis

Answer 412

- the drug must not only attach to its binding target but also must occupy an adequate number of binding sites, which is related to its concentration within the microorganism - to work effectively, the antimicrobial should remain at the binding site for a sufficient period of time in order for the metabolic processes of the bacteria to be sufficiently inhibited - must reach and stay at the site of bacterial infection

Answer 413

concentration and the time that the antimicrobial remains on the binding sites

Answer 414

* the ‘knockout punch’ | * key parameter is how high the concentration is above the MIC

Answer 415

- aminoglycosides | - quinolones

Answer 416

* sustained killing | * key parameter is the time that serum concentrations remain above the MIC during the dosing interval

Answer 417

- beta-lactams (penicillins, cephalosporins, carbapenems, monobactams) - clindamycin - macrolides (erythromycin, darithromeycin) - oxazolidinones (linezolid)

Answer 418

pharmokinetics - movement of a drug from its administration site to the place of its pharmacologic activity and its elimination from the body: - release from the dosage form - absorption from the site of administration into the bloodstream - distribution to various parts of the body, including the site of action - rate of elimination from the body via metabolism (liver) or excretion (kidney) of unchanged drug

Answer 419

- site of infection | - what antibiotics are safe for the patient

Answer 420

* which antibiotics will penetrate that site? * what is the pH of the site? * is the antibiotics lipid soluble?

Answer 421

* intolerance, allergy and anaphylaxis * side effects * age * renal and liver function * pregnancy and breast feeding * drug interactions * risk of clostridium difficile (antibiotic induced diarrhoea)

Answer 422

* Ciprofloxacin * Clindamycin * Cephalosporins * Co-amoxiclav (augmentin) * Carbapanems e.g. meropenem

Answer 423

- target site mutation - destruction of antibiotic - prevention of antibiotic entry - remove antibiotic from bacterium

Answer 424

bacteria changes the molecular configuration of its antibiotic binding site or masks it: - flucloxacillin (or methicillin) is no longer able to bind penicillin binding protein of Staphylococci in MRSA - wall components change in enterococci and reduce vancomycin binding - vancomycin-resistant enterococci

Answer 425

the antibiotic is destroyed or inactivated: - beta lactam ring of penicillins and cephalosporins can be hydrolysed by bacterial enzyme ‘beta lactamase’ meaning they are unable to bind to penicillin binding proteins and inhibit cell wall synthesis - Staphylococci produce penicillinase so penicillin but not flucloxacillin is inactivated

Answer 426

their beta lactam ring can be hydrolysed by bacterial enzyme beta lactamase, meaning they're unable to bind penicillin binding proteins and inhibit cell wall synthesis

Answer 427

they produce penicillinase, so penicillin but not flucloxacillin is inactivated

Answer 428

bacteria modifies its bacterial membrane porin channel size, numbers or selectivity

Answer 429

proteins in bacterial membranes can act as an export or efflux pump so the antibiotic is pumped out of the bacteria/microbe resulting in reduced levels and thus effect of antibiotic on bacteria/microbe: - S.aureus or S.pnuemoniae resistance to fluroquinolones - Enterobacteriacae resistance to tetracyclines

Answer 430

proteins act as an efflux pump so the antibiotic is pumped out, thus reducing the levels and effect of the antibiotic

Answer 431

proteins act as an efflux pump so the antibiotic is pumped out, thus reducing the levels and effect of the antibiotic

Answer 432

all subpopulation of a species will be equally resistant

Answer 433

- aerobic bacteria are unable to reduce metronidazole to its active form thus the antibiotic is harmless to them - anaerobic bacteria lack oxidative metabolism required to take up aminoglycosides - vancomycin is not taken up by gram negative bacteria - it cannot penetrate their outer membrane since its too large

Answer 434

unable to reduce it to its active form

Answer 435

lack oxidative metabolism to take them up

Answer 436

cannot penetrate their outer membrane since it is too large

Answer 437

* a bacterium which was previously susceptible obtains the ability to resist the activity of a particular antibiotic * only certain strains or subpopulations of a species will be resistant

Answer 438

- spontaneous gene mutation | - horizontal gene transfer

Answer 439

- new nucleotide base pair - change in amino acid sequence - change to enzyme or cell structure - reduced affinity or activity of antibiotic

Answer 440

conjugation, transduction and transformation

Answer 441

the transfer of genetic material between bacterial cells by direct cell-cell contact or by a bridge-like connection between two cells; takes place through a pilus

Answer 442

- genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous genetic material from its surroundings through the cell membrane - picking up naked DNA

Answer 443

process by which foreign DNA is introduced into a bacterial cell by a virus or viral vector

Answer 444

- MRSA | - VRE

Answer 445

* Methicillin resistant Staphylococcus Aureus * Staphylococcal casette cromosomi mec (SCCmec) contains resistance gene mecA * gene encodes penicillin-binding protein 2a (PBP2a) that does not bind penicillin i.e. resistance * confers resistance to all B-lactam antibiotics in addition to methicillin

Answer 446

Staphylococcal casette cromosomi mec

Answer 447

resistance gene mecA

Answer 448

penicillin-binding protein 2a (PBP2a) that does not bind penicillin

Answer 449

all beta-lactam antibiotics and methicillin

Answer 450

* Vancomycin-resistant enterococci * plasmid mediated acquisition of gene encoding altered amino acid on peptide chain preventing vancomycin binding * promoted by cephalosporin use

Answer 451

cephalosporin use

Answer 452

- beta-lactamases - ESBL - AmpC beta-lactamase resistance

Answer 453

* enzymes that hydrolyse penicillins * TEM-1 in E.coli, H. influenzae and N. gonorrhoea * SHV-1 in K. pneumoniae * but such strains typically remain sensitive to beta-lactamase inhibitors

Answer 454

extended spectrum beta lactamases

Answer 455

• have further mutation at active site means it can destroy more than just penicillin or amoxycillin • typically they can also inactivate: - cephalosporins e.g. cefuroxime, cefalexin, cefotaxime - combination antibiotics such as co-amoxiclav and tazocin

Answer 456

• broad spectrum penicillin, cephalosporine and monobactam resistance • beta lactamase inhibitor resistant in bacteria such as Citrobacter spp. and Enterobacter spp.

Answer 457

can be treated with quinolones or trimethoprim but may require carbapenam treatment or agents such as fosfomycin or temocillin (use for UTIs and chest infections)

Answer 458

- treatment | - prophylaxis

Answer 459

• specific indications: - endocarditis - post-splenectomy • prevention of post-surgical infection

Answer 460

- penicillins - cephalosporins - carbapenems - combinations (B lactam inhibitor/B lactam)

Answer 461

all beta lactams

Answer 462

* contraindicated for people who exhibit any type of allergy to penicillins * use with caution if patient has no true IgE mediated/severe allergy

Answer 463

* streptococci: e.g. S.pneumo and beta-haemolytic streps (A,B,C,G) * also treats some other gram positive bacteria including clostridia (gas gangrene) * IV * narrow spectrum

Answer 464

skin and soft tissue infection e.g. endocarditis

Answer 465

increasing resistance; enterococci are resistance

Answer 466

* bacterial pharyngitis - ‘strep throat’ * splenectomy prophylaxis * oral

Answer 467

* has greater activity than benzylpenicillin - broader * H. influenzae * Enterococci * Enterobactericae - E.coli, proteus, shigella

Answer 468

* pneumonia * skin and soft tissue infection * UTIs

Answer 469

- safe both orally and IV | - resistance is emerging

Answer 470

- IV and oral | - S. aureus

Answer 471

- benzylpenicillin/penicillin G (IV) - phenoxymethylpenicillin/pen V (oral) - amoxicillin (IV and oral) - flucloxacillin (IV and oral)

Answer 472

* B lactamases are enzymes produced by bacteria that hydrolyse penicillins and thus make them resistant * resemble traditional B-lactam antibiotic e.g. penicillin * they bind to the B-lactamase and protect the antibiotic from degradation

Answer 473

- clavulanic acid - sulbactam - tazobactam

Answer 474

combination of amoxicillin (beta lactam) and clavulanic acid (beta lactamase inhibitor)

Answer 475

combination of pipercillin (beta lactam) and tazobactam (beta lactamase inhibitor)

Answer 476

for example E.coli exhibits B-lactamase production: - it's resistant to amoxicillin - but it's sensitive to amoxicillin and clavulanic acid

Answer 477

* can be used in those with non-severe penicillin allergies | * can be used to treat meningitis

Answer 478

C. difficile and enterococci

Answer 479

ceftriaxone, cefotaxime (penetrates CNS)

Answer 480

earlier generations

Answer 481

newer generations

Answer 482

aztreonam (IV)

Answer 483

only gram negative rods/bacilli

Answer 484

- safe for those with penicillin allergies - has a lower C.diff risk - can only be used IV - has a narrow spectrum of activity

Answer 485

- meropenem - ertapenem - imipenem

Answer 486

- extended spectrum B-lactamases | - AmpC B-lactamases

Answer 487

hospital acquired infection (for the sickest and most at risk)

Answer 488

• broad spectrum, cover resistant gram negatives • expensive and have a C.diff risk • emerging resistance from carbapenemase producing enterobactericae

Answer 489

vancomycin and teicoplanin

Answer 490

- target the cell wall of bacteria | - gram positive only

Answer 491

- MRSA and other serious infections | - people with penicillin allergy

Answer 492

* must monitor nephrotoxicity (for vancomycin more than teicoplanin) * some resistance is possible (Vancomycin Resistant Enterococci (VRE))

Answer 493

clarithromycin and erythromycin

Answer 494

- inhibit protein synthesis - gram positives e.g. S. aureus and atypical pneumonia pathogens as well as group A streptococci - can cover MRSA

Answer 495

- severe/atypical pneumonia - penicillin allergic patients - MRSA - risk of C. diff as well as resistance

Answer 496

clindamycin

Answer 497

- inhibit protein synthesis | - gram positives e.g. S. aureus and anaerobes and group A streptococci

Answer 498

- cellulitis (if patient is allergic to penicillin) - necrotising fasciitis - MRSA - has a good oral bioavailability - C. diff risk

Answer 499

doxycycline (oral)

Answer 500

- inhibits protein synthesis | - broad spectrum

Answer 501

- cellulitis (if patient is allergic to penicillin) - MRSA - possibility of resistance

Answer 502

gentamicin (IV)

Answer 503

- inhibits protein synthesis - broad spectrum - enterobacteriaceae, staphylococci, synergistically to treat streptococci

Answer 504

- UTIs - infective endocarditis (synergistically) - can be used against extended spectrum B-lactams and AmpC B-lactams - requires monitoring due to the risk of nephrotoxicity

Answer 505

- inhibits protein synthesis | - gram positive e.g. MRSA and VRE

Answer 506

- serious/gram positive infection e.g. skin and soft tissue - good oral bioavailability and penetration - multiple side effects and interactions

Answer 507

ciprofloxacin (IV and oral)

Answer 508

gram negatives more than gram positives

Answer 509

- UTIs | - patients with penicillin allergy

Answer 510

* poor streptococcal activity * good oral bioavailability * can be used against extended spectrum B-lactams and AmpC B-lactams * C.diff risk

Answer 511

- inhibits nucleic acid | - anaerobic bacteria

Answer 512

intra-abdominal infection

Answer 513

* good oral bioavailability * cheap * emerging resistance

Answer 514

- folate inhibitor | - broad spectrum

Answer 515

* can be used against extended spectrum B-lactams and AmpC B-lactams * cheap * however there is increasing resistance

Answer 516

- e.g. Pseudomonas aeruinosa - hospital acquired infection - has inherent resistance mechanisms

Answer 517

* pip/tazobactam * ceftazidime * aztreonam (meropenem) * gentamicin * ciprofloxacin (the only oral option)

Answer 518

- E.coli - Staph saprophticus - Proteus - Klebsiella - Enterococcus

Answer 519

trimethoprim for 3 days (if uncomplicated and ‘well’)

Answer 520

- S.aureus | - Beta-haemolytic streptococci: Group A, C or G streptococci

Answer 521

flucloxacillin +/- benzylpenicillin for 10-14 days

Answer 522

- S.pneumonia | - ‘Atypicals’

Answer 523

amoxicillin/co-amoxiclav +/- darithromycin for 5 days

Answer 524

varicella zoster virus

Answer 525

- primary infection with this virus causes chickenpox, which may produce a mild childhood illness, although this can be severe in adults and immunocompromised patients - type of herpes virus

Answer 526

* after an incubation period of 14-21 days there is a brief period of fever, headache and malaise * rash is predominantly on the face, scalp and trunk (distribution is like a chickens feathers i.e the beak and legs are relatively untouched) * rash begins as macules and develops into papule and vesicles which heal with crusting * rash will accumulate at warmer areas e.g. shoulders and neck

Answer 527

* pneumonia - more common in adults than children * pneumonitis - healthy adults have a 15% risk * central nervous system involvement presenting as acute truncal cerebellar ataxia * exhibits viral dormancy in dorsal root or cerebral ganglion which can result in localised reactivation under immunosuppressed conditions - this is shingles (localised)

Answer 528

patients are infectious from 2 days before the rash appears since the virus replicates in the nasopharynx and thus can spread in the air

Answer 529

- due to reactivation of VZV - after the primary infection, herpes zoster remains dormant in the dorsal root ganglia and/or cranial nerve ganglia and reactivation results in shingles - a person with shingles (particularly if the rash is weeping) could cause chickenpox in a non-immune person after close contact and touch

Answer 530

* pain (neuropathic) and tingling in a dermatomal distribution precede the rash by a few days * the rash consists of papules and vesicles in the same dermatome * the most common sites are the lower thoracic dermatomes and the opthalmic division of the trigeminal nerve (most common)

Answer 531

- shingles can be a hallmark of HIV - red flag if multiple dermatomes are involved or peripheral dermatomes involved - these are unusual signs and need proper investigation for immunocomprimisation i.e. HIV

Answer 532

- bilateral limb hypoplasia and scarring - seen in 10-15% chickenpox in pregnancy - if maternal chickenpox in first half of pregnancy then 2% risk of foetal varicella syndrome in infants

Answer 533

hand foot mouth enterovirus

Answer 534

pop lesion and absorb the fluid and then test for chickenpox or enterovirus to find out what it is

Answer 535

classic infection that causes lesions on the palms, toes and back

Answer 536

- rare but severe disseminated infection that generally occurs at sites of skin damage produced by atopic dermatitis, burns, long term use of topical steroids or eczema - dermatological emergency

Answer 537

microorganisms capable of causing disease

Answer 538

the ability of a pathogen to become established in host, can involve adherence and immune escape

Answer 539

the ability of a pathogen to cause disease once established

Answer 540

the ability of a pathogen to penetrate mucosal surfaces to reach normally sterile sites

Answer 541

microbial factors that cause disease

Answer 542

- need rapid cell entry - free virus in blood stream is easily neutralised - infected cells are destroyed

Answer 543

* IgA - Blocks binding * IgM - agglutinates particles and makes it difficult to enter cells * complement - opsonisation and cell lysis * antibodies - neutralise toxins

Answer 544

* interferon (from T helper or T killer cells) has antiviral action - it induces anti-viral protein DAI (Double stranded RNA activated inhibitor of translation) on nearby cells so they cannot get infected * cytotoxic T lymphocytes kill infected cells (so any virus in cell cannot replicate)

Answer 545

double stranded RNA activated inhibitor of translation | - anti-viral protein induced by interferon

Answer 546

induces DAI on nearby cells so they cannot get infected

Answer 547

cytotoxic T lymphocytes kill infected cells (so any virus in cell cannot replicate)

Answer 548

* 3-4 days post infection the cytotoxic T lymphocyte activity increases * peaks at 7-10 days then declines * cytotoxic T lymphocytes eliminate virus infected cells and so eliminate sources of new viral products

Answer 549

* influenza virus to respiratory epithelium * varicella zoster virus (chicken pox) to skin cells * yellow fever virus to liver cells * HIV to CD4 T-cells

Answer 550

respiratory epithelium

Answer 551

skin cells

Answer 552

liver cells

Answer 553

much of the damage to cells in viral infection is indirect and caused by the innate or adaptive immune response

Answer 554

* respiratory tract * gastrointestinal tract * skin/mucous membrane break e.g wound

Answer 555

number of organisms, virulence and location

Answer 556

phagocytes activate

Answer 557

immune response

Answer 558

antibody response

Answer 559

cellular response

Answer 560

- bacteria compete with host cells and colonising flora - adhesins - biofilms

Answer 561

- sequestering nutrients - using novel metabolic pathways - out-competing other micro-organisms

Answer 562

help bacteria bind to mucosal surfaces

Answer 563

• fimbriae and pili filamentous proteins e.g Neisseria gonorrhoea • lipid e.g. lipid teichoic acid of Streptococcus pyogenes • glycosaminoglycans of Chlamydia sp.

Answer 564

- bacteria can stick together on a surface by secreting an extracellular polymeric substance of proteins, polysaccharides and DNA - helps protect against antimicrobials - seen in dental plaque, prosthetic materials and in ottis media (middle ear infection)

Answer 565

* S.aureus * Streptococcus mutans * Pseudomonas aeruginosa

Answer 566

secrete proteases which lyse IgA

Answer 567

secretes adhesion molecules

Answer 568

has a polysaccharide capsule that prevents phagocytosis

Answer 569

releases M protein that inhibits phagocytosis

Answer 570

produce coagulase that forms a fibrin coat round the organism thereby protecting it

Answer 571

secretes elastase which inhibits C3a and C5a (attracts neutrophils to site of inflammation)

Answer 572

escapes from phagolysosome and lives in cytoplasm

Answer 573

location of parasite in host

Answer 574

humoral immunity

Answer 575

cell mediated immunity

Answer 576

* do not multiple in humans (eggs formed) * not intracellular * few parasites carried * poor immune response

Answer 577

snail > larvae > human > liver > intestinal mesentery (bladder veins) > male + female (adult worms) > eggs > faeces/urine > snails

Answer 578

* IgG and IgE produced * IL5 - eosinophil production * IL3 - mast cell growth * eosinophil basic protein is toxic to worms

Answer 579

* decreased antigen expression by adult worms * glycolipid/glycoprotein coat is host derived so not perceived as foreign to the immune system - utilises host self antigens

Answer 580

* monocytes * neutrophils * endothelial cells (IL-1, TNFa)

Answer 581

* IL-8 | * C5a

Answer 582

* IL-8 * C5a * IFN gamma * LPS

Answer 583

* Prostaglandins | * Leukotrienes

Answer 584

* Prostaglandins * Leukotrienes * Kinins

Answer 585

* transplacental transfer * colostrum (in breast milk) * inject preformed antibody * tetanus toxoid * snake venom

Answer 586

* protective immunity * immunological memory * achieved by: natural infection and vaccine administration

Answer 587

* inactivated (killed) * attenuated (avirulent) * bacteria or viruses * toxoid vaccines (inactivated toxins)

Answer 588

- diseases, infections and conditions specifically listed as notifiable under the Public Health (Infectious Diseases) Regulations 1988 - it is the legal obligation for any doctor that suspects a case to inform the Proper Office of the Local Authority

Answer 589

HIV, bird flu or variant Creutzfeldt-Jakob (vCJD) disease (mad cow disease)

Answer 590

- acute encephalitis - acute infectious hepatitis - acute meningitis - acute poliomyelitis - anthrax - botulinism - brucellosis - cholera - diphtheria - enteric fever - food poisoning

Answer 591

- haemolytic uraemic syndrome - infectious bloody diarrhoea - invasive group A streptococcal disease - Legionnaires disease - leprosy - malaria - measles - meningococcal septicaemia - mumps - plague - rabies - rubella

Answer 592

- SARS - scarlet fever - smallpox - tetanus - TB - typhus - viral haemorrhagic fever - whooping cough - yellow fever

Answer 593

* anthrax * rabies (no treatment) * cholera * leprosy * malaria

Answer 594

* acute poliomyelitis (polio) * measles * mumps * rubella

Answer 595

* acute infectious hepatitis * scarlet fever * tuberculosis

Answer 596

- detection of any changes in a disease | - allows the development of interventions targeted at vulnerable groups

Answer 597

- outbreak detection - early warning - forecasting - extent and severity of disease - risk factors

Answer 598

- investigate to see who might have been exposed to the disease - identify and protect vulnerable persons - exclude high risk persons from high risk setting - educate, inform and raise awareness

Answer 599

* contact tracing | * partner notification

Answer 600

* chemoprophylaxis * immunisation * isolation

Answer 601

G, A, M, E and D

Answer 602

active and passive

Answer 603

* cell-mediated immunity | * antibody-mediated immunity

Answer 604

vaccination stimulates immune response and memory to a specific antigen/infection

Answer 605

- inactivated (killed) e.g. pertussis and inactivated polio - attenuated live organism e.g. yellow fever, MMR, polio and BCG - secreted products e.g. tetanus & diptheria toxins - the constituents of cell walls/subunits e.g. Hep B - recombinant components - experimental

Answer 606

- polysaccharide antigens are not as immunogenic as protein antigens (protein vaccine results in a stronger response) - protection is not long-lasting - response in infants and young children often poor

Answer 607

- must replicate in the vaccinated individual to produce an immune response - takes time (days or weeks) to replicate - usually does not cause disease but some may cause a mild form of the disease - avoid giving live attenuated vaccines to those who are immunocompromised since they are at risk of infection

Answer 608

protection provided from the transfer of antibodies from immune individuals

Answer 609

• most commonly it is cross-placental transfer of antibodies from mother to child e.g. measles, pertussis • or, via transfusion of blood or blood products including immunoglobulin e.g. Hep B • passive immunity provided by injection of human immunoglobulin containing antibodies to the target infection

Answer 610

* protection is temporary - usually only a few weeks or months * temporarily increases person’s antibody level to that specific infection * protection gained within a few days but lasts only a few weeks

Answer 611

human normal immunoglobulin (HNIG) derived from the pooled | plasma of donors and contains antibodies to infectious agents that are currently prevalent in the general population

Answer 612

used to protect immunocompromised children exposed to measles and of individuals after exposure to hepatitis A

Answer 613

person doesn't develop immunity from vaccine

Answer 614

initially responds but the protection wades over time

Answer 615

meningitis or septicaemia

Answer 616

- caused by Neisseria meningitis (gram negative); 10-20% carry this in the back of the throat - seen as gram negative purple diplococci under microscope

Answer 617

- infection is not easily spread - transmitted person to person by inhaling respiratory secretions from the mouth and throat or by direct contact (kissing) - close prolonged contact usually required - bacteria do not live long outside the body

Answer 618

* majority of infections occur in children (less than 5) * peak incidence in under 1s * smaller secondary peak in young adults (age 15-19) * less than 5% of cases occur in clusters * most cases are sporadic * outbreaks common among teenagers and young adults e.g. in schools and universities * marked seasonal variation with peak in winter * the winter season coincides with that of influenza

Answer 619

distinct serogroups, according to their polysaccharide outer capsule

Answer 620

* the most common pathogenic serogroups are groups B, C, A, Y and W135 * most disease in the UK is caused by serogroups B (59%) and C (36%) * significantly fewer cases caused by serogroup C since routine vaccination introduced

Answer 621

* brain abscess * brain damage * seizure disorders * hearing impairment * focal neurological disorders * organ failure * gangrene * auto-amputation due to arterial occlusions * death

Answer 622

- Cefotaxime | - Ceftriaxone

Answer 623

* case fatality rate around 10% | * more deaths caused by septicaemia than meningitis

Answer 624

- notification - contact tracing - prophylaxis

Answer 625

- contact for meningitis is taken to be any person having close contact with a case in the past 7 days - close contact includes: • kissing • sleeping with • spending the night together • spending in excess of eight hours in the same room

Answer 626

- warn about symptoms and signs - glass test: petechial spots do not blanch on pressure - contact telephone number

Answer 627

- for close, usually household contacts - Ciprofloxacin (older children and adults) or Rifampicin (not for pregnant women) - for nasal carriage - reduces spread - does not stop the disease if already incubating it

Answer 628

- if the serotype of meningococcus is vaccine preventable, a vaccination may be offered to unprotected contacts - depends on serogroup - but remember neither vaccine efficacy nor coverage is ever 100% - routine childhood immunisations: men B and C

Answer 629

sexy students can look bad comemorning - Streptococcus spp. - Staphylococcus spp. - Corynebacterium spp. - Listeria spp. - Bacillus spp. - Clostridium spp.

Answer 630

huge vaginas can never provide pleasure - Helicobacter - Vibrio cholera - Coliforms - Neisseria - Parvobacteria - Pseudomonas

Answer 631

HAPPH - Herpes viridae - Adenovirus - Parvovridae - Papopviridae - Hepaviridae

Answer 632

Clostridium

Answer 633

- C. perfringens - C. tetani - C. botulinium - C. difficile

Answer 634

- Cornyebacterium - Listeria - Bacillus

Answer 635

C. diptheriae

Answer 636

L. monocytogenes

Answer 637

B. anthracis | B. cereus

Answer 638

Neisseria | Moraxella

Answer 639

M. catarrhalis

Answer 640

B. fragilis

Answer 641

- Parvobacteria | - Helicobacter

Answer 642

- Haemophilus influenzae - Bordatella pertussus - Leigonella pneumonphilia - Brucella - Campylobacter jejuni

Answer 643

- Eschericia (E. coli) | - Klebsiella (K. pneumoniae)

Answer 644

- Salmonella - Shigella - Proteus

Answer 645

- S. typhi - S. paratyphi - S. enterica

Answer 646

- S. sonnei | - S. dysenteriae

Answer 647

- P mirabilis

Answer 648

- glycopeptides | - beta lactams

Answer 649

Vancomycin and Teicoplanin

Answer 650

- severe staph infections e.g. MRSA/C. difficile | - must be monitored to prevent ototoxicity and nephrotoxicity

Answer 651

- penicillins - cephalosporins - carbapenems

Answer 652

- benzylpenicillin - flucoxacillin - ampicillin/amoxicillin

Answer 653

Strep. infections, pneumococcal pneumonia, meningococcal meningitis, gonococcal infection, syphillis

Answer 654

S. aureus, S. pyogenes

Answer 655

UTIs, RTIs, listeria, meningitis, entercocci infections, S. pneumonia causing bronchitis

Answer 656

S. aureus, streptococci, nisseriae, Haemophilus, coliforms

Answer 657

imipenem, ertapenem

Answer 658

enterobacteriae, anaerobic bacteria

Answer 659

cautions: renal impairment, history of deafness, pregnancy SEs: nephrotoxicity, ototoxicity, blood disorders

Answer 660

CIs: penicllin hypersensitivity SEs: hypersensitivity reactions

Answer 661

CIs: penicillin hypersensitivity SEs: nausea, vomiting

Answer 662

CIs: cephalosporin sensitivity (10% allergic to penicillin will also be ceph sensitive) SEs: antibiotic associated colitis, Stephens-Johnson syndrome

Answer 663

CIs: breast feeding SEs: increased platelet count (ertapenem), neurotoxicity at very high doses

Answer 664

- inhibit folate synthesis - inhibit DNA gyrase - binds to RNA polymerase - DNA strand breaks

Answer 665

- trimethoprim - sulfonamides: sulfamethoxazole - co-trimoxazole: trimethoprim and sulfamethoxazole

Answer 666

UTI (not in pregnancy), prostatitis, acute/chronic bronchitis

Answer 667

PCP treatment and prophylaxis

Answer 668

fluoroquinolones: ciprofloxacin, ofloxacin, levofloxacin

Answer 669

Strep. viridans, Strep. pyogenes, Pseudomonas, H. influenza, campylobacter, Chlamydia spp.

Answer 670

rifampicin

Answer 671

Staph and Strep., mycobacteria (quad. TB treatment)

Answer 672

nitroidimazoles: metronidazole

Answer 673

anaerobes, parasites e.g. Giardia lambia, prophylaxis in GI surgery

Answer 674

CIs: blood dyscrasias cautions: pregnancy SEs: hyperkalaemia, depression of haematopoiesis

Answer 675

CIs: porphyria SEs: hyperkalaemia, rash

Answer 676

caution: epilepsy, G6PD deficiency, myasthenia gravis SEs: dyspepsia, sleep disorders, rash pruritus NB: predispose to MRSA as excreted through the skin and kills commensal organisms

Answer 677

CIs: jaundice SEs: orange discolouration of saliva and urine, anorexia, nausea and vomiting, haemolytic anaemia

Answer 678

CIs: interaction with alcohol -> profuse vomiting SEs: taste disturbance, anorexia

Answer 679

- chloramphenicol - macrolides - tetracyclines - aminoglycosides

Answer 680

- H. influenzae meningitis, epiglottitis, Chlamydia, richkettsiae - used widely in the developing world - extended periods of treatment can cause bone marrow depression - neonatal toxicity -> grey baby syndrome

Answer 681

Clarithromycin and Erythromycin

Answer 682

Strep. pneumoniae, S. aureus, Legionella, Chlamydia, mycoplasma pneumoniae

Answer 683

Tetracyclin and Doxycycline

Answer 684

- broad spectrum | - Strep. pneumonia, Strep. viridans, Strep. pyogenes, S. aureus, Chlamydia, mycoplasma

Answer 685

Gentamycin and Streptomycin

Answer 686

S. aureus, gram negative bacilli, used for severe sepsis

Answer 687

CIs: pregnancy, breast feeding SEs: blood disorders, optic neuritis, erythema multiforme, grey syndrome (abdominal distension, cyanosis, circulatory collapse)

Answer 688

CIs: hepatic impairment (azithromycin) caution: neonates <2 weeks risk of hypertrophic pyloric stenosis SEs: rash, arrhythmias, Stephens-Johnson syndrome

Answer 689

CIs: children <12 due to deposition in bone and teeth leading to hyperplasia. renal disease SEs: dysphagia, oesophageal irritation, photosensitivity, headache, visual disturbance

Answer 690

CIs: myasthenia gravis SEs: nephrotoxicity, auditory and vestibular damage. prolonged therapy -> hypomagnesaemia

Microbiology KP notes Flashcards

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