Pentatrichomonas hominis: first isolation from the feces of a dog with diarrhea in China.

A trichomonad-like parasite isolated from canine fecal samples in Changchun, China was successfully cultivated in vitro using RPMI1640 medium supplemented with 10% heat-inactivated calf serum and antibiotics. These were then subjected to scanning and transmission electron microscopy for ultrastructural study. This parasite has four anterior flagella of unequal length, one independent flagellum, and one recurrent flagellum. It exhibits an anterior nucleus, a Golgi complex, an axostyle, food vacuoles, and hydrogenosomes. These features are consistent with the ultrastructural characteristics of previously described Pentatrichomonas hominis. Polymerase chain reaction and sequence analysis of three genetic loci, including ITS1-5.8S rRNA-ITS2, 18S rRNA, and EF-1α, were also used to compare these samples with other trichomonad species. Molecular identification was also consistent with P. hominis. This is the first time that isolation of P. hominis has been isolated from dog in China, although several other strains of P. hominis have been isolated from human samples.