Superiority of amphotericin over nystatin in Thayer-Martin medium

Abstract

Vaginal and cervical specimens taken for the detection of gonorrhea frequently contain Candida albicans. Thayer-Martin medium containing nystatin (VCTN) is unsatisfactory because nystatin fails to selectively inhibit C. albicans. Thayer-Martin medium containing no nystatin was prepared with varying concentrations of amphotericin (VCTA) added, and this latter medium was compared with VCTN for its ability to selectively inhibit varying numbers of C. albicans. The effect of amphotericin on the recovery of varying numbers of Neisseria gonorrhoeae was also studied. VCTN failed to inhibit 10(1) to 10(6)C. albicans. VCTA suppressed growth of up to 10(6)C. albicans. The optimal concentration of amphotericin B appeared to be 100 mug/ml. VCTA containing 100 mug of amphotericin B per ml (VCTA 100) was not inhibitory for N. gonorrhoeae when a dense population was applied with a replicator. However, it was slightly inhibitory when 10(1) to 10(2)N. gonorrhoeae were applied over the entire surface of an agar plate, although the colony count on VCTA 100 was more than 50% of the counts on chocolate agar and 75% of the counts on VCTN. These properties of VCTA 100, when stored at 4 C, were stable for up to 2 weeks.