Hospital Acquired Infections

Question 1

Define the following:

a. Antimicrobial
b. Antibacterial
c. Antibiotic

Answer 1

a. Antimicrobial
Interferes with growth and reproduction of a microbe

b. Antibacterial
Commonly used to describe agents that reduce or eliminate harmful bacteria

c. Antibiotic
Type of antimicrobial that is used as medicine for humans and animals

Question 2

What is a health-care associated infection?

Answer 2

Infections that occur after exposure to healthcare Infection starts >48 hours after admission to hospital

Question 3

Why do health-care associated infections cost money to the healthcare system?

Answer 3

They increase the length of stay at hospital

Question 4

List some medical interventions that can increase the risk of infection.

Answer 4

Catheterisation  
Intubation  
Lines (e.g. central venous lines)  
Chemotherapy 
Prosthetic material

Question 5

State some other factors that increase the risk of infection in the hospital setting.

Answer 5

Dissemination by healthcare staff

Concentration of ill patients

Question 6

What are the ESCAPE pathogens?

Answer 6

Enterococcus faecium  
Staphylococcus aureus 
Clostridium difficile 
Acinetobacter baumanii 
Pseudomonas aeruginosa 
Enterobacteriaceae

NOTE:
ESC are Gram-positive (first three)
APE are Gram-negative (last three)

Question 7

What is the main problem with the escape pathogens?

Answer 7

They are antibiotic resistant

Question 8

What is the most frequent cause of bacteraemia by a Gram-negative bacterium?

Answer 8

Pathogenic E. coli

Question 9

What does pathogenic E. coli frequently cause?

Answer 9

UTI

Question 10

Which antibiotics is E. coli resistant to in many countries?

Answer 10

Cephalosporins (3rd gen resistance)

Question 11

Which antibiotics is E. coli still sensitive to?

Answer 11

Carbapenems

Question 12

State the target proteins and the method of resistance to the following classes of antibiotics:

a. Cephalosporins
b. Carbapenems
c. Methicillin
d. Vancomycin

Answer 12

a. Cephalosporins
Target: Penicillin binding proteins (PBP)
Resistance: Extended-Spectrum Beta-Lactamase (ESBL)

b. Carbapenems
Target: PBP
Resistance: Carbapenemase enzymes

c. Methicillin
Target: PBP
Resistance: alternative target (PBP2A), which has low affinity for methicillin and can function in its presence

d. Vancomycin
Target: peptidoglycan precursor
Resistance: synthesis of a different peptidoglycan precursor

Question 13

What is ESBL encoded on?

Answer 13

Plasmid

Question 14

What are carbapenemases encoded on?

Answer 14

Transposon

Question 15

What types of infections does Klebsiella pneumoniae tend to cause?

Answer 15

UTI

Respiratory tract

Question 16

Which group of patients are at risk of Klebsiella infection?

Answer 16

Immunocompromised

Question 17

Which classes of antibiotics are Klebsiella widely resistant to?

Answer 17

Cephalosporins, fluoroquinolones and aminoglycosides

Carbapenem resistance in the US

Question 18

Which group of patients are at risk of P. aeruginosa infection?

Answer 18

Immunocompromised

Question 19

Which class of antibiotics is P. aeruginosa widely resistant to?

Answer 19

Carbapenems

Question 20

What is the most important cause of antimicrobial resistant infection in the world?

Answer 20

MRSA

Question 21

What is Enterococcus faecium widely resistant to and by what mechanism?

Answer 21

Vancomycin

VRE synthesises a different peptidoglycan precursor that is not targeted by vancomycin
NOTE: causes blood stream infections

Question 22

Compare the structure of the cell wall of gram +ve and -ve bacteria?

Answer 22

Gram -ve
- thin peptidoglycan layer bounded by 2 lipid membranes with LPS (endotoxin) molecule within outer membrane
Gram +ve
-thick peptidoglycan layer (does retain crystal violet)