[Study on drug sensitivity against Comamonas testosteroni by Kirby-Bauer disk diffusion method].

Objective: To determine the drug resistance of Comamonas testosteroni (C. testosteroni) by the Kirby-Bauer (K-B) method without Clinical and Laboratory Standards Institute (CLSI) explanation or the minimum inhibitory concentration (MIC) method with the standard CLSI explanation to evaluate the sensitivity of K-B method in detection of C. testosteroni.


Methods: K-B method and MIC method was used to determine the sensitivity of C. testosteroni to Piperacillin, Cefepime, Piperacillin/tazobactam, Imipenem, Meropenem, Amikacin, Gentamicin, Tobramycin, Ceftazidime and Ciprofloxacin. The interpretation standard for Pseudomonas aeruginosa was temporary used for the K-B method. The coincident rate was compared between the two methods.


Results: The complete or partial coincident rate for K-B method and MIC method to detect Piperacillin and Cefepime was 97.4% or 2.6%; the complete coincidence rate to detect Piperacillin/tazobactam, Imipenem and Meropenem was 100%; the complete or partial coincident rate to detect Amikacin, Gentamicin and Tobramycin 94.7% or 5.3%; the complete or partial coincident rate to detect Ceftazidime was 97.4% or 2.6%; the complete or partial coincident rate to detect Ciprofloxacin 86.8% or 10.6%, and the full non-coincidence rate was 2.6%.


Conclusion: The results of drug sensitive test from the two methods are highly consistent. We suggest that the microbiology labs do not report the interpretive results for C. testosteroni with K-B method but report the test results.