ACCURACY OF THE E-TEST FOR DETERMINING AN TIMICROBIAL SUSCEPTIBILITIES OF NEISSERIA-MENINGITIDIS TO ANTIBIOTICS

The E-test was evaluated by comparison with the reference agar dilutio n method on 50 N. meningitidis strains belonging to serotypes A [13], B [17] and C [12] or not agglutinated, isolated in France and Djibouti from cerebrospinal fluid. All strains were sensible by the reference method to penicillin G, cefotaxime, chloramphenicol, ciprofloxacin, do xycyclin, rifampicin. For erythromycin, some strains were intermediate (7/50). N. meningitidis sero-group A ATCC 13077 was used as control. The E-test quantitative accuracy compared with agar dilution results w as 80% (+/- 1 log2) or 97% (+/- 2 log2). The E-test generally showed l ower inhibitory concentration values than the agar dilution method. So me technical problems appear in our experience : agar plates must be w ell dried ; on 8 5 mm diameter agar plates only one strip can be teste d. The E-test for determination of antibiotic resistance of N. meningi tidis is an easy but expensive method, which give reliable results wit h agar dilution.