IN-VITRO ACTIVITY OF METRONIDAZOLE ALONE AND IN COMBINATION WITH CLOTRIMAZOLE AGAINST CLINICAL ISOLATES OF TRICHOMONAS-VAGINALIS

Trichomonas vaginalis vaginitis is generally treated with oral metroni dazole. Widespread use of this drug has led, however, to selection of resistant strains. Topical therapy seems appropriate whenever systemic high dosage schedule cannot be adopted in order to overcome resistanc e. This study was designed to assess the activity of metronidazole alo ne and in combination with clotrimazole, an imidazole derivative for t opical use, against T. vaginalis. Tests were performed employing the a ntitrichomonas activity of a fixed ratio of metronidazole with clotrim azole (5:1) which has been recently suggested for topical therapy and the checkerboard technique. All tests were carried out under aerobic c onditions to maximize T. vaginalis resistance traits. Minimum inhibito ry concentrations (MICs) of metronidazole for the 12 strains studied w ere in the range reported in the literature (0.5-32 mu g/ml). The inte raction of metronidazole with clotrimazole as assessed by the checkerb oard technique gave an indifferent outcome with all the strains assaye d (FIC=1-2). The fixed concentration of drugs, however, produced syner gism (FIC=0.5) in 5 of 12 isolates. Spontaneous resistant strains were not selected from T. vaginalis exposed to sub-lethal levels of the dr ugs or by culturing a large inoculum in the presence of 1, 2, 4 and 8 times the MICs of metronidazole alone or in combination with clotrimaz ole. These results confirm and extend previous reports highlighting th e good in vitro efficacy of the association of metronidazole plus clot rimazole against T. vaginalis.