Performances of the Rapid Polymyxin Acinetobacter and Pseudomonas Tests for Colistin Susceptibility Testing

Objectives: Owing to the emergence of colistin resistance in nonfermenting Gram negative bacteria, reliable and rapid techniques for testing colistin susceptibility are needed. We evaluated the performances of the Rapid Polymyxin Acinetobacter and Pseudomonas tests using a collection of Acinetobacter baumannii and Pseudomonas aeruginosa clinical isolates. Methods: Colistin susceptibility of A. baumannii and P. aeruginosa isolates (colistin susceptible and colistin resistant) was tested with the Rapid Polymyxin Acinetobacter and Pseudomonas tests and compared with the broth microdilution method. Results: The Rapid Polymyxin Acinetobacter and Pseudomonas tests were able to detect all colistin-resistant and all colistin-susceptible A. baumannii and P. aeruginosa isolates within 4 hours. Conclusion: The Rapid Polymyxin Acinetobacter and Pseudomonas tests are reliable techniques for detecting colistin resistance. Overall, both techniques allow an accurate and a rapid screening (<4 hours) of colistin resistance in A. baumannii and P. aeruginosa.