Grande, G., Graziani, A., De Toni, L., Garolla, A., & Ferlin, A. (2024). Male Tract Microbiota and Male Infertility. Cells. https://doi.org/10.3390/cells13151275
Grande G, Graziani A, De Toni L, Garolla A, Ferlin A. Male Tract Microbiota and Male Infertility. Cells. 2024. doi:10.3390/cells13151275
Grande, Giuseppe, et al. "Male Tract Microbiota and Male Infertility." Cells, 2024.
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Unit of Andrology and Reproductive Medicine, Department of Medicine, University of Padova, Padova, Italy.
Some semen microbiota patterns are linked to low sperm quality
Some semen bacteria patterns are linked to low sperm quality in men. A narrative review of 27 human studies reports that more Prevotella and Pseudomonas were associated with low sperm concentration or reduced motility. Fewer Lactobacilli may mark low semen quality.
Key Findings
More Prevotella in semen was linked to oligozoospermia (low sperm concentration) and, in men with obesity, to asthenozoospermia (reduced sperm motility).
Higher Pseudomonas in semen was more frequently associated with asthenozoospermia (reduced motility) and oligozoospermia (low sperm concentration).
Fewer Lactobacilli, namely Lactobacillus crispatus, may mark low semen quality. A rise in Lactobacillus iners was considered a risk factor for lower sperm concentration.
One study found fewer Lactobacilli in semen of chronic prostatitis patients. In infertile men with normal sperm counts, leukocytospermia (white blood cells in semen) was linked to fewer Lactobacilli and more Streptococcus.
In the one study of semen microbiota and HPV, with six HPV-positive fertile men and 25 negative controls, Fusobacterium differed between the groups.
Interpretation
The authors wrote a narrative review, a summary of selected studies without pooled statistics. They searched PubMed through December 2023 and kept 27 original human studies from 424 results. The findings are associations between bacteria and semen results. The authors say the exact role of bacteria in semen is unknown and note a limited number of studies. The HPV result rests on one study. The review also notes that in testicular sperm samples, 50–70% of bacterial reads were contamination.
RRM Context
RRM evaluates both partners, and the authors point the same way when they suggest that future work consider a couple genital microbiota. RRM treats unexplained infertility as undiagnosed, and the review notes that many cases of infertility lack a known cause.
Our editorial summary of this paper, not the article's abstract.
Abstract
In recent years, several studies have analyzed the composition of the male genital tract microbiota and its changes in infertility or in different situations associated with infertility. The aim of this narrative review is to obtain more insight on this topic; in particular, to describe actual evidence about changes in the semen microbiota in patients with infertility, male tract infections, or HPV infections. In semen, an increase in semen Prevotella spp. is associated with oligozoospermia and with obesity-associated asthenozoospermia; an increase in Pseudomonas is more frequently associated with asthenozoospermia and oligozoospermia; a reduction in Lactobacilli spp. (namely in Lactobacillus crispatus) may represent a marker of low semen quality. However, an increase in Lactobacillus iners is considered a risk factor for a reduced sperm concentration. In patients with prostatitis, there is a reduction in Lactobacillus spp. and an increase in Streptococcus spp., opening important perspectives about the role of probiotic treatments in these patients. Finally, an increase in Fusobacteria spp. was observed in patients with an HPV infection. In the conclusion, we underline the interactions between the seminal and vaginal microbiota, so that further studies should focus on the "couple genital microbiota".
Male Fertility › Male Factor Causes › Lifestyle and Environment · Infections and the Reproductive Microbiome › Sexually Transmitted Infections › Human Papillomavirus
Giuseppe Grande, Andrea Graziani, Luca De Toni, Andrea Garolla, Alberto Ferlin
G Grande, A Graziani, L Toni, A Garolla, A Ferlin
PMID 39120306 39120306 DOI 10.3390/cells13151275 10.3390/cells13151275 Grande et al. 2024, Grande 2024
00240q980