THE INTERACTION OF LACTOBACILLUS-ACIDOPHILUS AND TRICHOMONAS-VAGINALIS IN-VITRO

Recent work with a mouse model of Trichomonas vaginalis infection indi cated that estrogenized BALB/c mice that were preinfected with Lactoba cillus acidophilus showed a greater duration of T. vaginalis infection as compared to a control group of mice that were not treated with L. acidophilus. To examine the interaction between T. vaginalis and L. ac idophilus further we performed in vitro competitive growth assays betw een the 2 species. Although the addition oft. acidophilus to the T. va ginalis cultures slowed the growth of the protozoa, the added bacteria did not increase trichomonad death. However, T. vaginalis had a delet erious effect on L. acidophilus growth in combined cultures when compa red to matched controls. Using an initial inoculum of 10(5)/ml, at 40 hr the control L. acidophilus concentrations had grown to 1.3 x 10(7)/ ml. However, in combined culture with T. vaginalis, L. acidophilus con centrations at 40 hr had fallen to 7.8 x 10(5)/ml and 6.1 x 10(4)/ml f or the 10:1 (T. vaginalis at 10(4)) and 1:1 (T. vaginalis at 10(5)) te st ratios, respectively (P < 0.01). This demonstrates that T. vaginali s can cause the concentration of L. acidophilus to fall in vitro and m ay explain why the concentration of L. acidophilus in the vagina falls in trichomoniasis.