[Heterogeneity of Brain Heart Infusion agar media (BHI): effects on the determination of the vancomycin and the teicoplanin minimal inhibitory concentrations (MIC) of Staphylococcus aureus strains].
The influence of BHI media commercially available on the results of glycopeptides MIC measured by E-test method was studied on 36 S. aureus isolates (21 MRSA and 15 MSSA). The MIC obtained with the vancomycin and the teicoplanin determined by the E-test method, on the ready prepared BHI plates (AES) and the plate prepared at the laboratory among the four dehydrated bases (AES, Biorad, Oxoid, and Becton Dickinson), were compared. The mean of the MIC showed variations from 3.14 (Biorad) to 5.25 mg/L (Oxoid) and from 3.33 (Biorad) to 9.75 mg/L (ready prepared AES) respectively for the vancomycin and for the teicoplanin. A variance analysis (Test de Friedman) showed a significant difference between the five media (p <0.001) with the two antibiotics. The comparison of media 2 by 2 allowed that all combinations excepted one (Biorad vs Becton with the vancomycin) were statistically different (p <0.001). The variation of the MIC observed in relation to the origin of the product of BHI media requires the inclusion of glycopeptide-intermediate S. aureus reference strains to control the prepared culture media.
Laboratoire de bactériologie-virologie-hygiène, centre hospitalier universitaire Dupuytren, 2, avenue Martin-Luther-King, 87042 Limoges cedex, France. christian.martin@unilim.fr
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D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001921:Brain; D003470:Culture Media; D006321:Heart; D006801:Humans; D008826:Microbial Sensitivity Tests; D011933:Reagent Kits, Diagnostic; D013211:Staphylococcus aureus / Q000145:classification* / Q000187:drug effects / Q000302:isolation & purification; D017334:Teicoplanin / Q000494:pharmacology*; D014640:Vancomycin / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D003470:Culture Media; D011933:Reagent Kits, Diagnostic; D017334:Teicoplanin; D014640:Vancomycin