M211-4

Wound: Pseudomonas aeruginosa – Shipped May 10, 2021

HISTORY

A simulated wound sample collected from 88-year-old elder care patient with a diabetic ulcer on foot was sent to category A laboratories.

Participants were expected to isolate Pseudomonas aeruginosa and perform susceptibility testing.

MAIN EDUCATIONAL POINTS from M211-4

1. In addition to beta-lactamases, other resistance mechanisms (eg. porin loss, impermeability) may play a role in an organism’s resistance to various beta-lactam agents. Different resistance mechanisms may demonstrate specific resistance patterns to various antimicrobials.
2. Porin loss (OprD) is the most common mechanism of imipenem resistance, however it does not usually reduce susceptibility to meropenem to the same extent – isolates with loss of the OprD porin alone will usually test as susceptible or intermediate to meropenem.

Full critique (PDF)