Resazurin microplate test method for rapid determination of colistin resistance in carbapenem-resistant Acinetobacter baumanii isolates.

Background: Colistin-resistant Acinetobacter baumannii isolates are extremely important pathogens for hospital-acquired infections.

Objective: To investigate the effectiveness of the resazurin microplate assay (REMA) for the rapid determination of colistin resistance.

Methods: Susceptibility for colistin was investigated in vitro by the broth microdilution method (BMD) and the resazurin microplate assay (REMA) on 106 carbapenem-resistant Acinetobacter baumannii isolates.

Results: The results of both test methods were compared, and the categorical agreement between them was found to be 100%. No minor, major, or very major discrepancy was observed between the 2 methods.

Conclusions: The most important advantages of REMA are that the results are obtained within 6 hours compared to the reference method, that it is easy to evaluate because it is colorimetric, and that the susceptibility result can be reported to the clinician on the same day as bacterial identification.