Associations of Adjunctive Multistrain Probiotic/Prebiotic Supplementation with Microbiological Eradication and Semen Parameters in Infertile Men with Male Tract Infections: A Retrospective Cohort Study

Background: Male tract infections (MTIs) represent a relevant cause of male factor infertility, yet microbiological persistence after antibiotic therapy remains common. This retrospective observational cohort study evaluated whether adjunctive multistrain probiotic/prebiotic supplementation was associated with microbiological and seminal outcomes in infertile men with microbiologically confirmed MTIs. Methods: One hundred infertile men with confirmed MTIs received either antibiotic therapy alone (n = 50) or antibiotics plus sequential multistrain probiotic/prebiotic supplementation (n = 50). The primary outcome was microbiological eradication. Secondary outcomes included changes in sperm concentration and total sperm count. Multivariable analyses adjusted for infertility duration, female partner age, pathogen category, and baseline semen parameters. Results: Microbiological eradication was achieved in 92.0% of patients receiving combined therapy versus 56.0% receiving antibiotics alone (adjusted OR 7.29, 95% CI 2.19–24.23; p = 0.001). Combined therapy was associated with greater improvements in sperm concentration and total sperm count, both when defined as any increase and as a ≥50% increase from baseline (all p < 0.01). These findings remained consistent across continuous analyses, pathogen-specific subgroup analyses, and sensitivity analyses excluding mixed infections. Conclusions: Adjunctive multistrain probiotic/prebiotic supplementation was associated with higher microbiological eradication rates and greater improvements in semen quality than antibiotic therapy alone. Prospective randomized controlled trials are warranted to confirm these findings and define the role of microbiota-targeted therapies in managing infertility associated with MTIs.