Isolation of Trichomonas vaginalis with Penicillin

Abstract

Exposure of Trichomonas vaginalis in vaginal discharge for 60 hours to 5,000-10,000 units of penicillin in 10.0 ml of a medium containing cysteine (0.15 per cent.), peptone, liver infusion, maltose and human serum was adequate to destroy the associated bacteria. Seven strains were isolated from seven women without a failure. This technic widens the field of investigation by offering a means of obtaining additional strains of bacteria-free Trichomonas vaginalis for comparative study. Efforts to isolate Trichomonas vaginalis by such laborious methods as washing, micropipetting and migration have all failed to yield bacteria-free cultures at this and other laboratories. The adherence of bacteria to the trichomonads, which appear to have sticky surfaces, and the relatively slow speed with which these protozoa swim are probably in large measure responsible for failure. Further trials by these methods now seem unnecessary. In the cases reported above the success of the penicillin method may be attributed to several factors. Resistance of Trichomonas vaginalis to penicillin in the concentrations reported above, the absence from the specimens of vaginal discharge of bacteria resistant to penicillin in these same concentrations, and the destruction of bacteria adherent to the sticky surfaces of the trichomonads perhaps played a large part in assuring successful isolation of the protozoa.