Trichomonas vaginalis causes trichomoniasis, the most recurrent sexually transmitted infection (STI) worldwide. Genital mycoplasmas, not considered STI agents, are frequently isolated from the female genital tract. A symbiosis between Mycoplasma species and T. vaginalis has been described. The aim of this study was to conduct molecular-based analyses of vaginal specimens, thus assessing the prevalence of non-STI Mycoplasma infections. In total, 582 samples from female patients and an additional 20 T. vaginalis isolates were analyzed by PCR using Mycoplasma specific 16S rRNA primers, and the obtained PCR products were sequenced. Mycoplasma species were detected in 28.2% of the collected vaginal samples. Mycoplasma hominis was found in 21.5% of the specimens, Ureaplasma species were found in 7.5% of the samples. The molecular data of the newly described species, CandidatusMycoplasma girerdii, were obtained for the first time in Austria, in a sample also positive for T. vaginalis. Analyses of the cultivated T. vaginalis strains confirmed the presence of M. hominis in two out of 20 samples. A comparably high prevalence of genital mycoplasmas was revealed through advanced diagnostic assays, with M. hominis and U. parvum being the most prevalent species. The previously described symbiotic relationship between M. hominis and T. vaginalis was confirmed.

Trichomonas vaginalis (TV) is the causative agent of trichomoniasis, the most common nonviral sexually transmitted disease. TV can carry symbionts such as Trichomonas vaginalis virus (TVV) or Mycoplasma hominis. Four distinct strains of TV are known: TVV1, TVV2, TVV3, and TVV4. The aim of the current study was to characterise TV isolates from Austrian patients for the presence of symbionts, and to determine their effect on metronidazole susceptibility and cytotoxicity against HeLa cells. We collected 82 TV isolates and detected presence of TVV (TVV1, TVV2, or TVV3) in 29 of them (35%); no TVV4 was detected. M. hominis was detected in vaginal/urethral swabs by culture in 37% of the TV-positive patients; M. hominis DNA was found in 28% of the TV isolates by PCR. In 15% of the patients, M. hominis was detected in the clinical samples as well as within the respective TV isolates. In 22% of the patients, M. hominis was detected by culture only. In 11 patients, M. hominis was detected only within the respective cultured TV isolates (13%), while the swab samples were negative for M. hominis. Our results provide a first insight into the distribution of symbionts in TV isolates from Austrian patients. We did not observe significant effects of the symbionts on metronidazole susceptibility, cytotoxicity, or severity of symptoms.

In Mycoplasma hominis, two genes (alr and goiB) have been found to be associated with the invasion of the amniotic cavity, and a single gene (goiC) to be associated with intra-amniotic infections and a high risk of preterm birth. The syntopic presence of Ureaplasma spp. in the same patient has been shown to correlate with the absence of goiC in M. hominis. The aim of our study was to investigate the presence of alr, goiB, and goiC genes in two groups of M. hominis isolates collected from symptomatic and asymptomatic male and non-pregnant female patients attending an Outpatients Centre. Group A consisted of 26 isolates from patients with only M. hominis confirmed; group B consisted of 24 isolates from patients with Ureaplasma spp. as the only co-infection. We extracted DNA from all M. hominis isolates and analysed the samples for the presence of alr, goiB, and goiC in a qPCR assay. Additionally, we determined their cytotoxicity against HeLa cells. We confirmed the presence of the alr gene in 85% of group A isolates and in 100% of group B isolates; goiB was detected in 46% of the samples in both groups, whereas goiC was found in 73% of group A and 79% of group B isolates, respectively. It was shown that co-colonisation with Ureaplasma spp. in the same patient had no effect on the presence of goiC in the respective M. hominis isolate. We did not observe any cytotoxic effect of the investigated isolates on human cells, regardless of the presence or absence of the investigated genes.