Comparative in vitro sensitivity to metronidazole of Trichomonas vaginalis with isolates and clones.

ABSTRACT

Isolates of Trichomonas vaginalis from a group of Thai women in Khon Kaen, Thailand were studies for their in vitro sensitivity to metronidazole. Forty-five isolates of T. vaginalis and further 226 laboratory clones of these isolates were examined for drug sensitivity under anaerobic conditions using the CPLM (Cysteine-Peptone-Liver infusion Maltose) medium. The in vitro sensitivity of T. vaginalis to metronidazole, recorded as MLC values revealed highly variable sensitivity profiles Greater than 90% of the trichomonads studies were susceptible to relatively low concentrations of metronidazole in the range of 1-10 micrograms/ml. The remaining fraction of trichomonads, appeared to be less sensitive and required higher concentration of drug to attain the MLCs. The highest recorded MLC was 60 micrograms/ml. The geometric mean MLC of the 45 isolates was 7.99 micrograms/ml while that of The influence of the individual clones of subpopulations of T. vaginalis on the observed sensitivity of the isolate was also examined. A positive linear relationship was observed between the MLC of the isolated and the MLC of the least sensitive clone of the same isolate (p less than 0.05). This suggests that the most resistant clone present within an isolate of T. vaginalis plays an important role in determining the overall drug sensitivity of the isolate.