Experimental analysis of some factors influencing variation in the flagellar number of Trichomonas hominis from man and other primates and their relationship to nomenclature

Abstract

An intestinal trichomonad from man and monkeys has been studied to determine the number of anterior flagella. Thirteen strains from man and 32 from a number of other primates were examined. Morphological studies and physiological results based on limited observations in culture indicate that in this study the strains are all one species. The characteristic flagellar number appears to be five although there is some variability. About 77% of the organisms had 5 anterior flagella, 17% had 4, 5% had 3, and 1% had flagella numbering less than 3 and more than 5. Five clone cultures were prepared from each strain in media conditioned by previous inoculation with mixed bacteria or with a single bacterial strain identified as Escherichia coli. Although clones prepared by the two methods gave different results in flagellar counts in comparison to the parent cultures, this variation was found to be due to environmental rather than genetic factors. The age of the culture, the variable division rate of the organism, and the bacterial flora of the culture were the most evident “environmental” factors which appeared to affect the percentage of organisms with the characteristic flagellar number. This intestinal trichomonad was identified for the first time from 12 primate species. The strains isolated from monkeys showed identical results to those from man. Trichomonas wenyoni is reported from 4 sources in two species of monkeys for the first time. The variability in the number of anterior flagella in the common intestinal trichomonad of man and other primates is so great that it does not seem feasible to classify it according to this characteristic. It is suggested that the name Trichomonas hominis be retained for this organism in preference to Pentatrichomonas hominis until a more adequate system of classification is adopted.