Resistance

Question 1

Comment on MRSA
(6)

Answer 1

Methicillin is a stable form of penicillin

Virtually all strains of S. aureus are penicillin resistant

MRSA emerged in 1970

MRSA resistant to other B-lactams and Fluoroquinolones (MDR)

Used to be a HCAI but HCAI has decreased and CA-MRSA has emerged since the 1990s

CA-MRSA is more virulent (PVL positive but does not display broad resistance)

Question 2

Comment on MRSA epidemiology

Answer 2

Proportion of S. aureus BSI caused by MRSA has been decreasing for the last 12 years

In 2021 only 11.6% were caused by MRSA (lowest yet)

Question 3

Write about MRSA surveillance

Answer 3

Nasal swabs
Using real time PCR e.g. GeneXpert MRSA/SA assay
Targets protein A or mecA (meth res) DNA sequences

Question 4

Prevalence of VRE

Answer 4

9% of all HCAI

Alteration of cell wall precursors
8 acquired resistance phenotypes
Van A and Van B phenotypes most clinically significant

Question 5

Van A resistance

Answer 5

High level, inducible resistance to vancomycin and teicoplanin

Question 6

Van B resistance

Answer 6

Moderate to high level resistance to vancomycin but susceptible to teicoplanin

Question 7

VRE resistance

Answer 7

Many isolates show resistance to combination therapy with B-lactam plus an aminoglycoside

Many isolates show resistance to vancomycin

Used to treat infection with vancomycin- resistant infections with E. faecium

Question 8

Klebsiella

Answer 8

Carbapenemase producing enterobacterales CPE

Commensal but frequently an opportunistic pathogen causing BSI, HCAI UTI, VAP pneumoniae

Question 9

What are the ESKAPEs

Answer 9

Enterococcus faecium
S. aureus
K. pneumoniae
Acinetobacter baumannii
P. aeruginosa
Enterobacter species

Question 10

What are the four main HCAIs

Answer 10

Central line associated blood stream infections
Catheter associated UTI
Ventilator associated pneumonia
Antimicrobial resistance