THE IN-VITRO SUSCEPTIBILITIES OF VAGINAL LACTOBACILLI TO 4 BROAD-SPECTRUM ANTIBIOTICS, AS DETERMINED BY THE AGAR DILUTION AND E-TEST METHODS

The minimum inhibitory concentrations (MICs) of cefaclor, co-amoxiclav , clarithromycin and ciprofloxacin for 59 strains of vaginal lactobaci lli were determined by both the reference agar dilution and E test met hods. With the exception of clarithromycin, there was poor correlation between the results obtained by the two techniques. This was most app arent for the beta-lactams studied, the MICs of cefaclor as determined by the E test being particularly difficult to define. The stability o f antimicrobial gradients in the E test may cause problems when testin g slow-growing bacteria and/or organisms which grow only under anaerob ic conditions. Accordingly, only those MICs determined by the agar dil ution method are reported. The percentages of susceptible isolates wer e as follows: clarithromycin, 100; co-amoxiclav, 100; cefaclor, 20; an d ciprofloxacin, 4. The administration of antimicrobials, such as cipr ofloxacin and cefaclor, which have poor activities in vitro against la ctobacilli, may therefore be advantageous to the host because it allow s the protective effects of the normal vaginal flora to be preserved.