Biological assay of potential trichomonacides in vitro using a counter apparatus.

Utilising the accuracy and speed of a Coulter Counter for cell counting and sizing, a new method of antimicrobial assay has been developed in which the potency of inhibitors is calculated on a mol/cell basis. A total of 72 potential trichomonacides were screened against Trichomonas vaginalis and the ED50 value estimated for 27 of the most interesting and potent compounds. The ED50 value for metronidazole was a mean of 5.12 fmol/cell and only 6 compounds were more potent. After the nitroimidazoles, the acridines were the most potent group of compounds. Only chlortetracycline and gramicidin caused an increase in mean cell size.