The Influence of Sexually Transmitted Bacteria and Human Papillomavirus on Sperm Parameters: Data from a Preliminary...

Background and Objectives: The microbiome plays a pivotal role in male infertility, with distinct microbial species exerting both beneficial and deleterious effects on reproductive function. Sexually transmitted bacteria and several viruses, including human papillomavirus (HPV), have been identified in semen. This cross-sectional study aimed to examine the prevalence of single and co-infections of sexually transmitted bacteria (STB)-such as Chlamydia trachomatis, Mycoplasma spp., and Ureaplasma spp.-with various HPV subtypes in Greek male partners of infertile couples and to evaluate their potential impact on sperm parameters. In addition, the possible effect of cryopreservation on the maintenance of these pathogens was assessed. Materials and Methods: Eighty-two semen samples were initially collected from 82 individuals undergoing routine sperm analysis. In total, 80/82 (97.6%) participants proceeded to further analysis, as 2/82 (2.4%) were excluded due to poor DNA quality. Results: A total of 18/80 (22.5%) sperm samples tested positive for STB, with Ureaplasma spp. representing the most frequently detected pathogen. Co-infection of Ureaplasma spp. and Mycoplasma hominis was observed in 4/80 (5%) samples. Twelve samples (12/80, 15%) were positive for HPV, including low-risk (LR) and high-risk (HR) types, and HPV 16 was the predominant HR genotype. Notably, a co-infection of STB and HPV was not found in our specimens. STB-positive samples demonstrated significantly higher sperm concentration and improved progressive motility compared with STB-negative samples. HPV-positive samples exhibited lower sperm volume and concentration and increased non-progressive motility compared with HPV-negative samples. Following three months of cryopreservation, LR HPV and STB were no longer detectable, whereas HR HPV types remained detectable. Conclusions: These preliminary findings are interesting, as they could be useful for routine screening of HPV and STB in sperm samples preserved in sperm banks and highlight the need for future research.