COMPARISON OF THE E-TEST AND REFERENCE AGAR DILUTION METHOD FOR SUSCEPTIBILITY OF GRAM-NEGATIVE ANAEROBIC ORGANISMS

Minimal inhibitory concentrations (MICs) of clindamycin, cefoxitin, im ipenem, and metronidazole were determined by the E-Test and a referenc e agar dilution method for 92 gram-negative anaerobic organisms. For 3 35 MIC pairs, the agreement between the two systems was 80.1%; 60 (17. 9%) differed by two or more twofold dilutions. The best agreement was observed with imipenem (91.7%) and the poorest with cefoxitin (67%). W ith the E-Test (PDM Epsilometer for antimicrobial susceptibility testi ng [AB Bodisk, Solna, Sweden]), MICs for individual organisms are simp le to achieve, although for certain antibiotics discrepancies with the reference method are unacceptable.