Ear: Pseudomonas aeruginosa  – Shipped November 2013


A simulated ear swab from a 45 year old diabetic woman with severe ear pain, including a physician request for susceptibilities, was sent to categories A and B laboratories.

Participants were expected to isolate and identify Pseudomonas aeruginosa, and to test and report antibiotic susceptibilities.


  1. Pseudomonas aeruginosa is the most common etiologic agent of malignant otitis externa. This syndrome requires aggressive systemic antimicrobial therapy, and unlike other ear isolates, antimicrobial susceptibility testing is necessary in these organisms.
  2. Carbapenem susceptibility testing may be challenging in P. aeruginosa, and is increasingly important as the carbapenems are used more commonly. Laboratories should ensure that their reporting guidelines are in concordance with current susceptibility breakpoints, such those published by CLSI or EUCAST.

Full critique (PDF)

Posted in Clinical Bacteriology Results, critiques