RESUMO
BACKGROUND: Infertility is a worldwide medical issue in which infection is recognized to play a major role. Pathogens trigger various mechanisms that impact fertility, either directly by affecting the physiological indices of semen or indirectly by disrupting the process of spermatogenesis. In the current work, the effect of in-vitro cultivation of Escherichia coli (E. coli), Candida non-albicans (C. non-albicans), and Trichomonas vaginalis (T. vaginalis) (as the most frequently reported sexually transmitted infections) was assessed on the physiological functions of the spermatozoa and the chemical characteristics of the seminal fluid. METHOD: The semen samples were exposed to cultures of E. coli, C. non-albicans, and T. vaginalis. The study analyzed the changes in motility, agglutination, viability, DNA fragmentation index (DFI%), seminal pH, and biochemical parameters at 1/2, 1, 1.5, 2, 2.5, 3.5 and 4 hours. RESULTS: Incubation of the semen samples with E. coli resulted in a progressive increase in agglutination, pH, and nitrite. The seminal glucose and the sperm motility, on the other hand, were reduced. The sperm vitality and seminal protein remained unaffected. C. non-albicans induced three forms of agglutination (head-to-head, tail-to-tail, and head-to-tail), lowered pH values and decreased the sperm motility, but did not alter the seminal protein, glucose, nitrite, nor the spermatozoa viability at the different tested time intervals. T. vaginalis resulted in increased seminal protein, and reduced glucose, pH, and motility. It also induced minimal agglutination and caused unchanged nitrite and sperm viability. The DFI% was increased in all pathogens with the C. non-albicans showing the highest DNA fragmentation index. CONCLUSION: Urogenital infection with E. coli, C. non-albicans, or T. vaginalis is assumed to affect the quality of semen through DNA fragmentation, agglutination and altered seminal chemical microenvironment.