Acquired Resistance to Colchicine in a Strain of Trichomonas vaginalis

Abstract

Trichomonas vaginalis Donné, 1837 can be made resistant to a variety of chemical compounds and is a suitable organism for the study of resistance, particularly as it can be maintained indefinitely in bacteria-free cultures. Moreover, it possesses a cytostome and ingests relatively large granules (for example, rice starch), and probably acquired resistance in the case of this flagellate does not depend on non-transit of a particular compound through the surface membrane as is apparently the case in resistant trypanosomes. Thus a strain of T. vaginalis was made resistant to 4.4′-diamidino stilbene. Initially the strain tolerated not more than 1 in 70,000; but by culturing repeatedly on gradually increasing concentrations, a strain was obtained which grew in a concentration of 1 in 5,000. 4.4′-Diamidino stilbene fluoresces in ultra-violet light, and it was easy to demonstrate its presence in the cytoplasm of resistant flagellates grown on a concentration of 1 in 5,000¹. On the other hand, we failed to make an Indian strain of Leishmania donovani and a Sudan strain of L. infantum resistant to this drug by the usual method of sub-culturing in gradually increasing concentrations.