Mesut Berkan DURAN, Kürşat KÜÇÜKER, Aykut AKINCI, Yusuf ÖZLÜLERDEN, Sinan ÇELEN, Ahmet KOLUMAN
Journal of Urological Surgery - 2026;13(3):144-154
For decades, the male genitourinary tract was considered sterile in healthy individuals. However, advances in culture-independent molecular techniques, particularly next-generation sequencing, have revealed that semen contains a diverse microbial ecosystem known as the seminal microbiome. This paradigm shift has led to growing interest in the relationship between microbial composition and male reproductive health. Current evidence suggests that male infertility is associated not merely with the presence of bacteria in semen, but with alterations in microbial balance, termed seminal dysbiosis. Beneficial genera such as Lactobacillus are often associated with normal sperm parameters and genomic stability, whereas increased abundance of opportunistic and pathogenic bacteria-including Escherichia coli, Enterococcus faecalis, Ureaplasma urealyticum, and Prevotella-is associated with reduced sperm motility, abnormal morphology, and decreased sperm concentration. The pathological mechanisms underlying this relationship involve both host-mediated and pathogen-mediated pathways. Dysbiosis has been suggested to promote chronic inflammation and leukocytospermia, leading to excessive production of reactive oxygen species and consequent oxidative stress. This environment promotes lipid peroxidation and sperm deoxyribonucleic acid (DNA) fragmentation, key contributors to impaired fertilization and poor reproductive outcomes. Despite increasing recognition of the seminal microbiome's role in infertility, current diagnostic approaches remain limited. Culture-based methods frequently fail to detect viable but non-culturable microorganisms, while molecular assays cannot reliably distinguish viable pathogens from residual DNA. Improved diagnostic strategies targeting microbial viability and virulence may therefore play an important role in addressing unexplained male infertility.
