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Micro Lec 5 Flashcards

HAI (61 cards)

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1
Q

What is HAI

A

hospital acquired infection

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2
Q

What is nasocominal infection

A

Pertaining to or originating in the hospital

Not present on admittance to the hospital

Occurring 72hrs after admittance

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3
Q

In the community, the rate of infection is much lower and the types of infection are different, why

A
  • Patients are compromised by underlying illness.
  • Patients with similar predisposing factors or illnesses are confined within the same area.

-Healthcare workers move between patients.

-High usage of immunosuppressive drugs and antimicrobials.

-New patients who are susceptible to infection are continually introduced into the environment.

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4
Q

What are the predominant pathogens in HAI

A

UTI
Surgical Wound Infection
Lower respiratory infections
Bacteraemia

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5
Q

What are examples of predominant pathogens (UTI)

A

E. coli (other Gram-negative bacilli)
Enterococci
Staphylococci
Candida

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6
Q

What are some examples of predominant pathogens (surgical wound infection)

A

Staphylococci (S. aureus and CNS)
Enterococci
E. coli, Pseudomonas aeruginosa (other Gram- negative bacilli)

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7
Q

What are some examples of predominant pathogens (lower respiratory infections)

A

Pseudomonas aeruginosa (other Gram-negative bacilli)
S. aureus

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8
Q

What are some examples of predominant pathogens (Bacteraemia)

A

Staphylococci (S. aureus and CNS)
Enterococci
Candida
E. coli (other Gram-negatives bacilli)

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9
Q

What are the two sources of nosocomial infection

A

endogenous source
exogenous source

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10
Q

Provide an example of endogenous nosocominal infection source

A

coagulase negative staphylococci (CNS)

from the patient themself

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11
Q

Provide an example of an exogenous source of nosocominal infection

A

C. difficile

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12
Q

List the routes of transmission for nosocominal infection

A

Airborne
Droplet spread
Direct contact
Fomites
Common vehicle

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13
Q

Outline features of staphylococci

A

Gram-positive cocci arranged as irregular clusters
Approx. 1mm in diameter
Facultative anaerobe
Colonies grey, white, pale yellow on BA
S. aureus maybe haemolytic
Catalase-positive

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14
Q

List the coagulase negative staphylococci

A

S. epidermidis
S. saprophyticus
S. haemolyticus

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15
Q

What two types of infection can be caused by S. aureus

A

Superficial infections
Serious life-threatening infections

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16
Q

List some superficial infections caused by S. aureus

A

Boils
Sties
Impetigo
Food intoxication

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17
Q

List some serious life-threatening infections caused by S. aureus

A

Septicaemia
Endocarditis
Osteomyelitis

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18
Q

Outline the features of stphylococcus aureus

A

Gram positive cocci, irregular grape like clusters
Facultative anaerobe
Non-spore forming
Resistant to dry, salty conditions
Typical commensals of skin and upper respiratory tract

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19
Q

What is S. aureus

A

an opportunistic pathogen

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20
Q

what is biofilm in S. aureus

A

aggregate of micro-organisms embedded in extracellular matric

clinical implications

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21
Q

What is quorum sensing in S. aureus

A

Cell-cell communication that enables bacteria to gauge cell density and adjust gene expression accordingly, and work as one collective team

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22
Q

What are MSCRAMMS in S. aureus

A

Microbial surface components recognizing adhesive matrix molecules
Involved in bacterial attachment to host tissue
Attached covalently to peptidoglycan
Participate in biofilm formation and deep seated and device related infection

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23
Q

What is S. aureus resistant to

A

penicillin
meticillin

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24
Q

Outline the features of meticillin

A

Belongs to the second generation of penicillins
Beta-lactamase resistant

Other antibiotics of this type include:
Oxacillin
Flucoxacillin

Sensitive strains - MSSA
Resistant strains - MRSA

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25
HOW ARE SEVERE INFECTIONS CAUSED BY METICILLIN SENSITIVE s. AUREUS (MSSA)
Flucloxacillin (beta-lactam) Erythromycin, clindamycin or vancomycin if the patient has a penicillin allergy
26
Severe infection caused by meticillin resistance S. aureus (MRSA)
Vancomycin (glycopeptide)
27
newer antibiotics include
Linezolid, daptomycin, ceftobiprole
28
Provide some examples of coagulase negative staphylococci (CNS)
S. epidermidis S. haemolyticus S. saprophyticus
29
Outline th features of S. epidermidis
polysaccharide slime biofilm tolerant to antibiotic treatment
30
List some examples of indwelling medical devices
Urinary catheters Endotracheal tubes Continuous Ambulatory Peritoneal Dialysis (CAPD) catheters Feeding lines Intravascular catheters
31
Outline the signs of infection at the exit site
Inflammation at exit site, tenderness, swelling, cellulitis, purulent exudate
32
What does catheter-related blood stream infection lead to
bacteraemia, septicaemia, endovcarditis, septic shock
33
How are intravscular device related infections diagnosed
exit site swab maki roll plate blood culture
34
What organisms cause intravascular device-related infection
S. epidermidis S. aureus E.coli andf other gram negative bacilli Enterococci Candida
35
List some typical exogenous pathogens
antibiotic resistant organisms MRSA ESBLs Clostridium difficile
36
Outline the features of clostridium difficile
Gram-positive, oval sub-terminal spore Anaerobe Motile Not usually member of commensal intestinal flora Antibiotic associated diarrhoea and pseudomembranous colitis
37
What can antibiotic therapy lead to
Loss of normal bacterial gut flora C. difficile grows to high numbers (exogenous or endogenous) Toxin production Diarrhoea Ulcerations of the colon Death
38
How is C. diff diagnosed
Enrichment and selective isolation Braziers CCEY agar Detection of GDH and toxin Enzyme linked immunosorbent assay
39
How is C. diff treated when severe
Metronidazole or oval vancomycin Fidazomincin - narrow spectrum, oral antibiotic
40
What are alternative treatment options to treat C. diff
- probiotics - Faecal transplants/enemas - Absorbents for toxins - Immunotherapy - either active or (probably more useful) passive immunisation - usually trageted to neutralisation of toxins
41
How can endogenous infection be prevented
Screen patients on admission Limit time between admission and surgery Selective bowel decontamination Prophylaxis Use of antibacterial treated dressings and devices Care of intravascular devices Appropriate use of antiseptic preparations Vaccination
42
How are exogenous infection prevented
Airborne: single occupancy rooms, isolation with positive pressure, ventilation systems in theatre, appropriate care of ventilation systems, monitoring of air quality, use of HEPA filters in theatres such as orthopeadics – ultra clean theatres Direct contact: use of sterile equipment, regular hand washing, use of gloves and aprons, alcohol hand rubs (also used by visitors, porters etc), barrier nursing. Indirect contact: design of hospitals to allow efficient cleaning, appropriate use of disinfectants, environmental screening. Vaccination of staff with Hep B, BCG protects them and the patients. High risk patients ie neutropenics may be vaccinated against varicella zoster (but only gives short term protection).
43
What are the possible outcomes of HAI
Serious illness or death Possibility of permanent disability Increased length of hospital stay Increased use of antimicrobials Increased costs Potential risk of infection to other patients
44
What two factors contribute to immunocompromisation
Primary immunodeficiency (1_) is congenitally acquired or a form of inherited disease. Secondary immunodeficiency (2_) are acquired after birth
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What types of pathogens can affect immunocompromised patients
Typical pathogens Opportunistic pathogens Environmental organisms
47
What is Chronic granulomatous disease
Mutation in an NADP-dependent oxidase which ultimately affects the production of hydrogen peroxide by phagocytes. Usually fatal in childhood. S. aureus, Aspergillus.
48
What is 1degree Affecting Adaptive Immunity - SCID
Group of rare congenital disorders characterised by impairment of both humoral and cell-mediated immunity; leukopenia and low or absent antibody levels. S. pneumoniae, H. influenzae, Candida, viruses, Pneumocystis jiroveci.
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SLIDE
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50
List some examples of 2 degree affecting innate immunity - trauma by burn
Pseudomonas aeruginosa Other Gram-negative bacilli S. aureus S. pyogenes Other streptococci Enterococcus species Candida and Aspergillus
51
Outline the features of Pseudomonas aeruginosa
Gram-negative motile bacillus. Non-fastidious, strict aerobe. Oxidase-positive. Characteristic pyocyanin pigment Forms biofilms. Opportunistic pathogen (e.g. CF). Carriage rate 10%, increasing to 30% in hospitalised patients.
52
What three types of infection are associated with P. aeruginosa
Water associated Hospital associated Immunocompromised
53
Provide examples of water associated infections caused by P. aeruginosa
Otitis externa. Keratitis. Corneal ulcers. Folliculitis.
54
Provide examples of hospital associated infections caused by P. aeruginosa
Catheter related UTI. Infected ulcers and bed sores. Burns.
55
Provide examples of immunocompromised infections caused by P. aeruginosa
Lung colonisation in cystic fibrosis. Septicaemia, pneumonia.
56
How is P. aeruginosa diagnosed in labs
CBA, AZT, CLED, MHA. Oxidase test. Gram film MALDI-TOF, Vitek 2, GN ID card. Biochemical confirmations. API20NE.
57
How is P. aeruginosa treated
it is innately resistant so treated through combination therapy. Aminoglycoside. E.g. Gentamicin. _-lactam. E.g. Ceftazidime, Imipenem.
58
What does neutropenia result from
Acute leukaemia. Treatment for leukaemia. Other treatment drugs.
59
When is there risk of infection in neutropenic patients
Significant risk of infection at < 0.5x109 neutrophils/L. Very high risk of infection at < 0.1x109 neutrophils/L.
60
Outline the features of neutropenia
Gram positive cocci S. epidermidis, streptococci, diphthroids, enterococci. Gram negative bacilli Coliforms, Pseudomonas aeruginosa Fungi Candida, Aspergillus Anaerobes Bacteroides, Clostridium difficile Antibiotic treatment.
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