Evaluation of two rapid phenotypical tests-Alifax rapid AST colistin test and Rapid Polymyxin NP test-for detection of colistin resistance in Enterobacterales

Our study evaluates the performance of two rapid phenotypical tests to detect colistin resistance in Enterobacterales: Alifax rapid AST colistin test using the HB&L system and Rapid Polymyxin NP test prepared in-house. A collection of well-characterized 53 colistin-susceptible and 66 colistin-resistantEnterobacterales isolates was used. The results obtained using both rapid tests were compared to the reference broth microdilution. Overall categorical agreement was 81.5% for Alifax test and 98.3% for Rapid Polymyxin NP test. Based on our results, the Rapid Polymyxin NP test is superior to the Alifax test that performed inadequate for Enterobacter spp.

Automated summary

Our study demonstrates that the Rapid Polymyxin NP test is superior to the Alifax test in detecting colistin resistance in Enterobacterales, particularly in the Enterobacter spp.