5: Hospital Acquired Bacterial Infections

Question 1

Sources of hospital infection

Answer 1

Intervention

• Chemo
• Catheterisation
• Intubation
• IV lines
• Prosthetic material

Dissemination (i.e. people in hospital already have infection so easy to spread)

Concentration (lots of people in one place so easy to spread infection)

Question 2

Main pathogens in hospitals

Answer 2

ESCAPE

+Enterococcus faecium (vancomycin resist.)
+Staph aureus (methicilin resist. aka MRSA)
+Clostridium difficile
- Acinetobacter baumanii (high drug resist.)
- Pseudomonas aeruginosa (multi-drug resist.)
- Enterobacteriaceae (E.coli, Klebsiella, Enterobacter) multi drug resistant

Question 3

What is Pathogenic E.coli

Answer 3

Commonest cause of bacteraemia by gram - bacterium
Commonest cause of UTI
Increase in multi-drug resistant strains

Most strains that are resistant to cephalosporins (beta-lactam antiobiotic) express ESBL (extended spectrum beta lactamase) which CLEAVES the drug
Beta lactams inhibit peptidoglycan synthesis by inhibiting penicilin-binding proteins (PBPs)

Question 4

Drug resistance in pathogenic E.coli?

Answer 4

Cephalosporins (beta-lactam)
Most strains that are resistant to cephalosporins express ESBL (extended spectrum beta lactamase) which CLEAVES the drug

Beta lactams inhibit peptidoglycan synthesis by inhibiting penicilin-binding proteins (PBPs)

More sensitive to carbapenems, but still see some resistance (carbapenemase enzyme bla kpc)

Question 5

Klebsiella pneumoniae

Answer 5

UTI + resp tract infections
Risk group = immunocompromised
High proportion resistance to 3rd gen cyclosporins
carbapenem-resistant Kp (CRKP) most common CRE seen in US

Question 6

Pseudomonas aeruginosa

Answer 6

Cause of infection in immuno-compromised

High proportion of strains resistant to antimicrobials

Question 7

MRSA - how does resistance work

Answer 7

Most important cause of antimicrobial infection worldwide
Methicilin = beta lactam
Resistance due to expression of ADDITIONAL PBP
Low affinity for methicilin - can still synthesise peptidoglycan

Question 8

Vancomycin resistant Enterococcus faecium (VRE) - how does it work?

Answer 8

Resistance around 60%

Vancomycin also inhibits PG synthesis by binding to PG precursor
Resistance - synthesis of a different PG precursor