Correlation study of two routine bacteriology systems with previously characterised strains.

Abstract

The objective of this study was to evaluate the performance of the VITEK 2 and Advanced Expert System (bioMérieux) for antimicrobial testing of previously characterised Gram-positive and Gram-negative bacterial strains. These strains obtained from bioMérieux, Mrcy Le Toille, France, were well characterized with regard to the existing resistance mechanisms and the Minimal Inhibitory Concentration (MIC) values were determined by agar dilution. VITEK 2 was also compared with the Sceptor system (Becton Dickinson) routinely used in our laboratory. The results obtained were equally good for VITEK 2 and Sceptor with a rate of agreement between the two systems of 91.4% and 88.2% respectively. When the results were evaluated in relation to the different antibiotic concentrations, the agreement was 94% for VITEK 2 and 62% for Sceptor. The resistance mechanisms associated with each resistance pattern were determined by the Advanced Expert System (AES) in 79.6% of strains. The VITEK 2 provided, in 3-4 hours, an acceptable level of accuracy in testing antimicrobial sensitivity in Gram-positive and Gram-negative strains with diverse mechanisms of resistance found in clinical situations.