[Value of the E-test for the determination of the susceptibility to antibiotics of Neisseria meningitidis].

The E-test was evaluated by comparison with the reference agar dilution 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, doxycyclin, rifampicin. For erythromycin, some strains were intermediate (7/50). N. meningitidis serogroup A ATCC 13077 was used as control. The E-test quantitative accuracy compared with agar dilution results was 80% (+/- 1 log2) or 97% (+/- 2 log2). The E-test generally showed lower inhibitory concentration values than the agar dilution method. Some technical problems appear in our experience: agar plates must be well dried; on 85 mm diameter agar plates only one strip can be tested. The E-test for determination of antibiotic resistance of N. meningitidis is an easy but expensive method, which give reliable results with agar dilution.