Microbiology > Gram (-) > Flashcards

Gram (-) Flashcards

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1
Q

gram (-) - colour

A

pink

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2
Q

Gram (-) - subgroups

A
  1. diplococci
  2. coccoid robs (cocciobacilly)
  3. robs
  4. oxidase (+) comma shaped robs
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3
Q

Gram (-) - subgroups - diplococci - bugs and maltose

A
  1. Neisseria meningitis (malose)
  2. Neisseria gonorrhoeae (non-maltose)
  3. Moraxella catarrhalis (non-maltose)
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4
Q

Gram (-) - subgroups - diplococci - neisseria - bugs (and characteristics

A
  1. Neisseria meningitis (maltose fermenter, polysaccharide capsule, glucose fermenter)
  2. Neisseria gonorrhoeae (maltose nonfermenter, no capsule, glucose fermenter)
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5
Q

Gram (-) - subgroups - coccoid robs - bugs?

A
  1. haemophilus infleunzae
  2. Pasteurella
  3. Brucella
  4. Bordetella pertusis
  5. Francicella tularencis
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6
Q

Pasteurella - transmission by

A

animal bite

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7
Q

H. influenza - media (and its contains)?

A

Chocolate agar - Factor V (NAD+) and X (hematin)

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8
Q

Gram (-) - subgroups - oxidase +, comma shape

A
  1. Campylobacter jejuni (grows in 42c, oxidase +, comma shape)
  2. Vibrio cholera (grows in alkaline media, oxidase +, comma shape)
  3. Helicobacter pylori (produces urease, oxidase +, comma shape, catalase +)
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9
Q

Gram (-) stain robs are divided to (only the groups)

A
  1. Lactose fermeter

2. Lactose nonfermenter

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10
Q

Gram (-) stain robs - Lactose nonfermenter are divided to

A

oxidase -

oxidase +

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11
Q

Gram (-) stain robs - oxidase (+) Lactose nonfermenter - bugs (and their characeristic)

A

Pseudomonas - rob, oxidase (+),

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12
Q

Gram (-) stain robs - oxidase (-) Lactose nonfermenter - are divided to

A

H2S producers and non producers (TSI AGAR)

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13
Q

Gram (-) stain robs - oxidase (-) Lactose nonfermenter - bags and their characteristics

A
  1. Salmonela - lacose nonfermeter, oxidase -, H2S producer
  2. Proteus - lacose nonfermeter, oxidase -, H2S producer
  3. Yersinia - lacose nonfermeter, oxidase -, not H2S producer
  4. Shigella - lacose nonfermeter, oxidase -, not H2S producer
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14
Q

Gram (-) stain robs - lactose non fermenter bugs

A
  1. pseudomonas
  2. shigella
  3. salmonella
  4. proteus
  5. Yersinia
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15
Q

Gram (-) stain robs - lactose fermenter bugs (and characteristics)

A
  1. klebsiella (rob, fast lactose fermenter)
  2. E. coil (rob, fast lactose fermenter)
  3. Enterobacter (rob, fast lactose fermenter)
  4. citrobacter (rob, slow lactose fermenter)
  5. serratia (rob, fast lactose fermenter)
  6. others (rob, fast lactose fermenter)
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16
Q

Gram (-) stain robs - lactose fermenter are divided to

A

fast and slow fermenters

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17
Q

Gram (-) stain - lactose fermatation - appearance

A

fermantation of lactose –> fermentation produces acid pink colonies on MacConkey agar

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18
Q

lactose fermatation - agar?

A

MacConkey agar

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19
Q

E. coli is a lactose fermenter - mechanism

A

E. coli produces β-galactosidae, which breaks down lactose into glucose and galactose

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20
Q

EMB

A

eosin-methylane blue agar

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21
Q

EMB - lactose fermenting bacteria –>

A

lactose fermenters grow as purple/black colonies

E. coli grows colonies with a green sheen

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22
Q

Neisseria - media (and its contains)?

A

Thayer - Martin - vancomicin , trimethoprim, colistin , nystatin

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23
Q

Thayer - Martin contains … (and action)

A
  1. vancomicin –> inhibits gram (+)
  2. trimethoprim
  3. colistin –> inhibits gram (-) except Neisseria
  4. nystatin –> inhibits fungi
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24
Q

neisseria produce (virulence factor)

A

IgA protease

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25
neisseria gonococci vs neisseria meningitis - capsule
neisseria gonococci --> no capsule | neisseria meningitis --> polysaccharide capsule
26
neisseria gonococci vs neisseria meningitis - maltose fermentation
neisseria gonococci --> no | neisseria meningitis --> yes
27
neisseria gonococci vs neisseria meningitis - vaccines
neisseria gonococci --> no | neisseria meningitis --> yes (type B not widely available)
28
neisseria gonococci vs neisseria meningitis - transmission (via)
neisseria gonococci --> sexual or perinatally | neisseria meningitis --> respiratory or oral secretions
29
neisseria gonococci vs neisseria meningitis - manifestations
neisseria gonococci --> 1. gonorrhea, 2. septic arthritis, 3. neonatal conjunctivitis, 4. PID, 5. Fitz-Hugh-Curris syndrome, 6. prostatitis, 7. epididymitis, 8. osteomyelitis (RARE) neisseria meningitis -->1. meningococcemia with petechial hemor and gangrene of toes, 2. meningitis, Waterhouse-Friderichsen syndrome (adrenal insuf, fecer, DIC)
30
neisseria gonococci vs neisseria meningitis - prevention
neisseria gonococci --> condoms (for STD), erythromycin ointment (neonatal transmision) neisseria meningitis --> Rifampin, ciprofloxacin or ceftriaxone prophylaxis in close contacts
31
neisseria gonococci vs neisseria meningitis - treatment
neisseria gonococci --> ceftriaxone + (azithromycin or doxycycline) for possible chlamydial coinfection neisseria meningitis --> ceftraxone or penicillin G
32
neisseria gonococci vs neisseria meningitis - intracellular
neisseria gonococci --> yes | neisseria meningitis --> no
33
neisseria gonococci - vaccination
no --> due to antigenic variation of pilus proteins
34
MC complications in men and women of gonococcal urethritis
men: epididymitis, prostatitis, urethral strictures women: sterility, ectopic pregnancy, peritonitis, perihepatitis
35
what type of immunodeficiency has the greatest risk of N. meningitides bacteremia
C6-C9 deficiency
36
Waterhouse-Friderichsen syndrome?
fulminant meningococcemia leading to septic shock and bilateral adrenal hemorrhage causing catastrophic adrenal insufficiency and deaths in hours
37
Gram (-) - subgroups - coccoid robs - bugs?
1. haemophilus infleunzae 2. Pasteurella 3. Brucella 4. Bordetella pertusis 5. Francicella tularencis
38
haemophilus infleunzae - characteristics
small gram (-) coccoid robs (coccobacillary)
39
haemophilus infleunzae - transmission
aerosol transmission
40
H. influenza - media (and its contains)?
Chocolate agar - Factor V (NAD+) and X (hematin)
41
H. influenza - stains (clinical relevance)
1. Nontypeable stains (non-vaccine) | 2. tybe b stain (vaccine)
42
Nontypeable stains are the MCC of
A. mucosal infection: 1. otitis media 2. conjunctivitis 3. bronhitis
43
H. influenza produces
IgA protease
44
H. influenza can also be grown with .....
S. aureus, which provides factor V (NAD+) through the hemolysis of RBCs.
45
en-capsuled type B H. influenza causes
invasive infection: 1. meningitis 2. acute epiglottitis (children) 3. septic arthritis 4. sepsis
46
acute epiglottitis - appearance
endoscopy: cheery red | x-ray: thumbprint signs (thickening of epiglottis on lateral neck radiograph)
47
H. influenza - treatment
1. mucosal infection --> amoxicillin +/- clavulanate | 2. meningitis --> ceftriaxon.
48
H. influenza - prophylaxis in close contacts
rifampin
49
H. influenza - prevention / given when
vaccine contains type b capsular polysaccharide and PRP (polyribosylribitol phosphate) conjugated to diptheria or other protein given between 2 and 18 monthes of age
50
Legionella pneumonophila - characteristics
gram (-), --> gram stains poorly
51
Legionella pneumonophila - staining
gram ((-)) stains poorly --> SILVER STAIN
52
silver stain is used to stain
1. Fungi (eg. Pneumocytosis) 2. Legionella 3. Helicobacter pylori
53
Legionella - media?
charcoal yeast extract agar buffered with cysteine and iron
54
Legionella - detection
1. by presence of antigen in urine | 2. Labs may show hyponatremia
55
Legionella - transmission
--> aerosol transmission from environmental water source habitat (eg. air condition systems, hot water tanks) (NO PERSON - PERSON)
56
Legionella - treatment
macrolide or quinolone
57
Legionella pneumophilla --> ....
1. Legionnaires's disease | 2. Pontiac fever
58
Legionnaires's disease?
severe pneumonia (often unilateral and lobar), fever, GI and CNS symptoms
59
Pontiac fever is caused by / manifestation
- Legionella pneumophilla | - mild flu-like syndrome
60
risk factors for Legionnaires's disease
1. Cigarette smoking 2. alcoholics 3. chronic lung disease 4. immunosuppressed states
61
Pseudomonas aeroginosa - characteristics
Aerobic, motile, gram (-) rob, Non lactose fermenting, oxidase (+)
62
Pseudomonas aeroginosa - oxidase? / lactose?
- oxidase + | - Non lactose fermenting
63
Pseudomonas aeroginosa - appearance
1. pyocacin (blue-green pigment) | 2. grape-like odor
64
Pseudomonas aeroginosa - mechanism of action
produce 1. endotoxin --> fever + shock 2. exotoxin A --> inactivates EF-2 3. pyocacin --> generates ROS
65
pseudomonas aeroginosa - manifestations (and associated conditions)
1. Pneumonia (Cystic fibrosis, mechanical ventilation) 2. otitis externa - swimmer's ear (diabetes) 3. UTI (hospital patients) 4. ecthyma gangrenosum (immunocompromised patients) 5. sepsis 6. osteomyelitis (eg. puncture wounds, drug use) 7. wound infection (burn victim) 8. hot tub folliculitis (water) 9 nosocomial infections (catheter equipment)
66
ecthyma gangrenosum - definition and appearance
rapidly progressive necrotic lesion caused by pseudomonas aeroginosa. Large ulcers with necrotic regions. Typically seen in immunocompromised patients
67
conditions associated with pseudomonas aeroginosa infection
1. Cystic fibrosis 2. mechanical ventilation 3. hospital 4. immunodeficiency 5. puncture wounds 6. drug use 7. water 8. burn victim
68
pseudomonas aeroginosa - pneumonia - mechanism of action
Mucoid polysaccharide capsule may contribute t ochronic pneumonia in cystic fibrosis patietns due to biofilm formation
69
Pseudomonas aeroginosa - treatment
1. extended spectrum β-lactams (eg piperacillin, ticarcillin, cafepime) 2. Carbapenems (eg imipenem, meropenem) 3. Monobactams (eg aztreonam) 4. Fluoroquinolones (eg ciprofloxacin) 5. Aminoglycosides (eg. gentamycin, tobramicin) 6. For multidrug resistant stains --> colistin, polymyxin B 7. 3rd and 4th generation cephalosporines
70
Pseudomonas aeroginosa - treatment for multidrug resistant stains
colistin | polymyxin B
71
Pseudomonas aeroginosa - otitis externa - swimmer's ear is associated with
diabetes
72
Pseudomonas aeroginosa - UTI is associated with
hospital patients
73
Pseudomonas aeroginosa - osteomyelitis is associated with
puncture wounds, drug use
74
Pseudomonas aeroginosa - wound infection is associated with
burn victim
75
Pseudomonas aeroginosa - hot tub folliculitis is associated with
water
76
Pseudomonas aeroginosa - eye
it can cause corneal ulcer in contact lens wearers
77
E coli - virulence factors and associated diseases
1. fibmbriae --> cystitis and polynephritis (P-pili) 2. capsule (K) --> pneumonia, neonatal meningitis 3. LPS --> septic shock
78
E coli - strains
1. EIEC (Enteroinvasive) 2. ETEC (Enterotoxigenic) 3. EPEC (Enteropathogenic) 4. EHEC (Enterohemorrhagic)
79
EIEC (Enteroinvasive) - toxins and mechanism
main virulence factors by plasmid shared by shigella --> proteins for adherence and direct invasion (no toxins) invades intestinal mucosa and causes necrosis and inflammation
80
EIEC (Enteroinvasive) - presentation
dysentery with white blodd cells fever (similar to shigella)
81
ETEC (Enterotoxigenic) - main virulence factors
produce heat-labile and heat stable toxin enterotoxins | NO INFLAMMATION OR INVASION
82
ETEC (Enterotoxigenic) - presentation
traveler's diarrhea (watery)
83
Head-labile toxin (LT) - mechanism of action
Overactivates adenylate cyclase (increases cAMP) --> increases CL- secretion in gut and H20 efflux
84
Head-stable toxin (ST) - mechanism of action
overactivates guanylate cyclase (increases cGMP) --> decreases resorption of NaCL and H20 in gut
85
EPEC (Enteropathogenic) - toxins and mechanism
No toxins | Adheres to apical surface, flattens villi --> prevent absorption
86
EPEC (Enteropathogenic) - presentation
watery diarrhea, usually in children
87
EHEC (Enterohemorrhagic) - toxin and mechanism
shiga - like toxin --> a. enhances cytokines release --> hemolytic uremic syndrome b. GI mucosa damage --> dysentery
88
Shiga like toxin - mechanism of action
inactivates 60S ribosome by removing adenine from rRNA
89
hemolytic uremic syndrome -->
triad of anemia, thrombocytopenia and acute renal failure due to microthrombi forming on damage enthothelium --> mechanical hemolysis (schistocytes on peripheral smear, platelet consumption, and decreased renal flow
90
EHEC (Enterohemorrhagic) - presentation
1. dysentery (toxin alone causes necrosis and inflammation) | 2. triad of hemolytic uremic syndrome (anemia, thrombocytopenia and acute renal failure)
91
hemolytic uremic syndrome - peripheral smear
schistocytes
92
EHEC (Enterohemorrhagic) is also called / MC serotype is US
STEC (shiga toxin-producing E. col) | O157:H7
93
E-coli is a lactose fermenter - mechanism
E. coli produces β-galactosidae, which breaks down lactose into glucose and galactose
94
how to distinguish EHEC from other E. coli
EHEC does not ferment sorbitol
95
E. coli - presentation
1. EIEC --> dysentery with white blood cells, fever 2. ETEC --> traveler's diarrhea (watery) 3. EPEC --> watery diarrhea, usually in children 4. EHEC --> dysentery, hemolytic uremic syndrome
96
EHEC - trasnmission
undercooked meat, raw leafy vegetables
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