The endosymbiotic relationship between Trichomonas vaginalis and Mycoplasma hominis in Egyptian Women and its correlation with pathogenicity

Background Trichomonas vaginalis is the etiological parasite of trichomoniasis. Endosymbiotic Mycoplasma hominis can exist in T. vaginalis populations. However, its consequences are not yet known. Recently, T. vaginalis isolates positive for M. hominis as proven by PCR had greater cytopathic effects on human vaginal epithelial cells and also on Madin–Darby canine kidney cells in vitro. Objective This study aimed to detect the presence of M. hominis infecting Egyptian T. vaginalis isolates and to evaluate the pathogenicity of this association in vivo. Patients and methods Forty-five symptomatic and asymptomatic T. vaginalis isolates were obtained from Suez Canal and General Hospitals, Ismailia city, Egypt. All isolates were axenically cultivated in Diamond’s TYM medium, followed by DNA extraction and PCR using primer pair targeting 16S rRNA gene to detect M. hominis-infected isolates. Positive M. hominis PCR products were subjected to sequencing analysis. All isolates were experimentally inoculated intravaginally in female albino mice to assess the pathogenicity of different isolates. Results The detection rate of M. hominis-positive T. vaginalis isolates was 20% as determined with PCR. No statistically significant association was recorded between M. hominis-infected T. vaginalis among symptomatic and asymptomatic isolates. Experimental mice infection showed varying degrees of inflammation by the different isolates. Conclusion To our knowledge, this study is the first report of T. vaginalis infection by M. hominis among Egyptian isolates and it was deduced that the association of M. hominis and T. vaginalis does not affect the clinical presentation of vaginal trichomoniasis and does not cause enhanced pathological changes in infected mice.