Comparison of in vitro susceptibility of Neisseria gonorrhoeae to trimethoprim-sulfamethoxazole on three different media.

In vitro susceptibility of 100 clinical isolates of Neisseria gonorrhoeae to trimethoprim-sulfamethoxazole (TMP-SMZ combination; 1:19) was determined by the agar dilution technique using three different media under similar conditions. On Oxoid diagnostic sensitivity test, Mueller-Hinton, and GC agar media, the percentage of isolates inhibited by 2.5 mug or less of TMP per ml and 47.5 mug or less of SMZ per ml were 95, 90, and 84%, respectively. TMP-SMZ appeared to be effective in vitro against N. gonorrhoeae despite differences in the types of media used.