Lab Med Qual Assur.  2022 Mar;44(1):36-39. 10.15263/jlmqa.2022.44.1.36.

Evaluation of the Reliability of Automated Colistin Susceptibility Assays of Pseudomonas aeruginosa

• Kim YA
• Kim J
• Son YJ
• Lee SS

• KMID: 2527803
• DOI: http://doi.org/10.15263/jlmqa.2022.44.1.36

Abstract

Background
With the increase in multidrug-resistant (MDR) gram-negative rods, colistin treatment is increasingly required. Reliable susceptibility testing is important for managing infectious patients with MDR Pseudomonas aeruginosa. This study evaluated the reliability of an automated colistin susceptibility assay.
Methods
In total, 195 non-duplicated P. aeruginosa blood isolates were collected from nine sentinel hospitals in Korea in 2020. Colistin susceptibility with Sensititre KNIHCOL Trek diagnostic system (Thermo Fisher Scientific, England), a commercial broth microdilution (BMD), was compared with that of the gram-negative MIC panel type 44 card (Beckman Coulter, USA). Isolates with discrepant results were reconfirmed using AST-N225 (bioMérieux SA, France).
Results
Categorical agreement was 92.8%, and nine colistin-resistant isolates with BMD were colistin-intermediate with two automated colistin susceptibility assays.
Conclusions
The failure to detect colistin-resistant P. aeruginosa could not be safely excluded with an automated colistin susceptibility assay.

Keyword

Colistin; Automated susceptibility assay; Broth microdilution; Pseudomonas aeruginosa