Infection and Inflammation of the Seminal Tract: A Review of Its Relationship to Male Fertility

Treating seminal tract infections improves sperm parameters and reduces DNA fragmentation — but no evidence shows it increases conception rates

Journal: Actas Urológicas Españolas | Published: 2026-01-05 | Type: Narrative Review | PMID: 41500460 Authors: Vives Suñé Á (Fundació Puigvert, STI Unit / Male Health Unit); Cosentino M (Casa di Cura Letizia, Milan — andrologist) Funding/COI: Funding not listed; authors declare no conflict of interest

Summary

The WHO has attributed 15% of male infertility to genital tract infections since 1997, and this review surveys the mechanisms, pathogens, and treatment evidence. Chlamydia trachomatis and Ureaplasma urealyticum have largely displaced Neisseria gonorrhoeae as the dominant culprits, and a substantial proportion of these infections are asymptomatic. The central finding is a frustrating dissociation: antibiotics improve semen parameters and reduce sperm DNA fragmentation, but there is no evidence they increase natural conception probability.

Claims

• WHO (1997) classifies infections of the male accessory gland — urethritis, prostatitis, vesiculitis, orchitis, epididymitis — as causes of infertility, accounting for ~15% of male infertility cases
• Historically the leading infectious cause was Neisseria gonorrhoeae; currently Chlamydia trachomatis, Ureaplasma urealyticum, and gram-negative uropathogens predominate
• Evidence supports that treating STIs improves semen parameters
• Antibiotics can improve sperm quality and reduce DNA fragmentation values
• No evidence that antibiotic treatment increases the probability of natural conception
• A "remarkable percentage" of STIs affecting the seminal tract are asymptomatic (no specific percentage cited)
• Authors recommend ruling out infection during initial andrological evaluation in couples seeking fertility

Study Quality

This is a narrative review, not a systematic review. The methods section states the authors "carefully evaluated the most representative reports" from a PubMed search — a phrase that describes subjective curation, not a reproducible protocol. There is no PRISMA flowchart, no defined inclusion/exclusion criteria, no quality assessment of included studies, and no synthesis of effect sizes across papers. The claim that treating STIs improves semen parameters is stated without quantification: no pooled effect size, no number of supporting studies, no breakdown by pathogen or treatment.

The review's alignment with "European and American guidelines" is cited as validation, but guidelines themselves rest on the same body of evidence — this is circular support, not independent corroboration.

Red Flags

• Narrative review with no systematic methodology — high risk of selection bias in which papers were included
• Key claims lack numbers: "improved semen parameters" without reporting the magnitude of improvement or the studies behind it
• "Remarkable percentage" of asymptomatic STIs asserted without a citation or figure
• Funding source not disclosed — for a review touching on antibiotic treatment protocols, this matters
• Two-author review from clinical practice settings; no academic institution affiliation; no methodologist co-author
• The critical negative finding (no conception benefit from antibiotics) is stated without citing the evidence base for it

Strengths

• Covers a clinically underemphasized area: seminal tract infection is frequently overlooked in infertility workup
• The dissociation between surrogate endpoints (sperm parameters) and clinical outcomes (conception) is an important and honest finding to highlight
• Framing around the WHO classification provides a useful clinical taxonomy
• Clear practical conclusion: screen for infection at initial andrological evaluation

Verdict

The clinical point buried in this review — that antibiotics fix the sperm on paper but don't demonstrably get anyone pregnant — is worth knowing. The review itself, however, is a thin narrative summary masquerading as a rigorous synthesis. Without effect sizes, study counts, or methodological grading, readers have no way to evaluate how strong the evidence actually is. Treat this as a readable orientation to the topic and a pointer toward the primary guidelines it cites, not as an authoritative evidence summary.