Abstract:

Objective: Haemophilus influenzae is a pathogen that can cause severe infections. Accurate determination of H. influenzae susceptibility is important to ensure treatment efficiency. This study aimed to evaluatethe performance of TDR NH-AST kit for testing the antimicrobial susceptibility of Haemophilus influenzae. Methods: A total of 101 isolates were collected from clinical laboratories. Broth microdilution method was performed following the Clinical and Laboratory Standards Institute guideline M07-A10 as the reference method. The category agreement (CA), essential agreement (EA), major discrepancy (MD) and very major discrepancy (VDM) were used to evaluate the agreement between the TDR NH-AST kit and reference method according to ISO 20776-2. Kappa value was calculated and McNemar test was performed to analyze the consistency between the two methods. Results: A total of 18 antimicrobial drugs were involved. Apart from meropenem, the Kappa values of the other antimicrobial drug susceptibility test were all higher than 0.75, and the P va-lues were all higher than 0.05 except ampicillin. The overall values of CA, EA, MD and VMD were 97.80%, 95.38%, 2.07% and 3.29%, respectively. Although EAs of meropenem, azithromycin and ciprofloxacin were slightly less than 90% (88.12%, 84.16% and 88.12%, respectively), all the other antibacterial drugs were more than 90%, and CAs of all antibacterial drugs were more than 90%. Conclusions: TDR NH-AST has a good consistency, accuracy and reliability in the detection of antimicrobial susceptibility of H. influenzae, and could meet the requirements of routine clinical antimicrobial susceptibility test of H. influenzae.

Key words: Antimicrobial susceptibility test, Haemophilus influenza, Evaluation agreement, Broth microdilution method, Minimal inhibitory concentration