Evaluation of susceptibility testing methods for Burkholderia cepacia complex: a comparison of broth microdilution, agar dilution, gradient strip and EUCAST disc diffusion

ObjectivesTo evaluate the accuracy and reproducibility of antimicrobial susceptibility testing methods in Burkholderia cepacia complex (BCC).MethodsMinocycline, ciprofloxacin, trimethoprim/sulphamethoxazole, meropenem, ceftazidime chloramphenicol were tested against 155 BCC strains using broth microdilution at 35 ± 1°C (BMD35) triplicate, then BMD 30 (BMD30), agar dilution 30°C 35°C (AD30 AD35), gradient strip (GS) EUCAST standardized disc diffusion (DD) once.ResultsBMD35 ranged from 70% to 84.5% for all agents. Correlations MICs BMD35 with BMD30 63% 85%, AD35 32.9% 87% GS 36% 83.9%. Essential agreement (EA) by 62.6% (trimethoprim-sulphamethoxazole) 83.9% (minocycline). EA DD zone diameters CLSI breakpoint criteria was between 85.8% 97.4%, however Very Major Errors (VME) trimethoprim/sulphamethoxazole 31%.ConclusionsBMD poorly reproducible most agents no method showed acceptable performance. Of particular concern results. Although this is commonly used determining laboratories, there poor correlation meropenem trimethoprim/sulphamethoxazole. correlated MICs. This study confirms that capable providing accurate when BCC.