Abstract
The effect of pH upon the growth of Trichomonas vaginalis is probably related to the problem of clinical control of the organism in cases of natural infection. This paper concerns the extremes of pH which will support growth in vitro and the optimum pH for the multiplication of the organism in bacteria-free culture.† 1
The culture medium used was Difco liver infusion agar slants overlaid with 5% human serum in modified Ringer's solution sterilized by filtration.‡ The pH of both the agar slants and fluid medium was adjusted with N/1 HC1 and buffered with 0.25% sodium phosphate. The incubation temperature was 37.5 ± 1°C. The pH determinations were made with a glass electrode which was checked against two standard buffers.
The organisms were counted in a hemocytometer after 2, 4, and 6 days of incubation. Each count included 10 large squares, having a total volume of 1 cu mm. Six cultures were examined at each pH except in those cases where extraneous circumstances reduced the number to 5. Only minor shifts in pH were observed during incubation and the experimental cultures did not vary markedly from the uninoculated control tubes. The greatest difference between experimental and control tubes was found to be 0.3 of 1 pH unit on the fourth day. Blood agar or chocolate agar plates were used to detect bacterial contamination at the conclusion of each experiment. Three cultures out of 305 used in 2 series and one subculture were found to be contaminated.
Optimum growth after 2 days' incubation occurred between pH 5.45 and 5.55, while after 4 days it was between 5.5 and 5.8. The highest pH supporting growth after 4 days was 7.55, the lowest 4.9.
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