Trichomonas foetus, Trichomonas hominis and Trichomonas vaginalis live much longer in media permitting their growth in the presence of bacteria, than they do in pure cultures in CPLM medium. In a diphasic medium of horse serum and rice starch, T. hominis, associated with a pure strain of E. coli and incubated at 25°C., keeps for more than 4 months; T. foetus and T. vaginalis, incubated at 37°C. with E. coli will keep for more than a month. Comparing these periods of time with those cited by Lamy (1953), who keeps T. vaginalis and T. hominis in the presence of mixed bacterial flora, it may be observed that better results are obtained by freeing the flagellates from the mixed flora and associating them with a pure strain of E. coli. To transfer from cultures mixed with bacteria to pure cultures in CPLM medium, it is sufficient to make one transfer in this medium with the addition of 1000 µg/cc. dihydrostreptomycin and 1000 U/cc penicillin.
The method of conserving strains of T. hominis, T. foetus and T. vaginalis here described requires fewer transfers than the methods hitherto in use.