Microbiota of the seminal fluid from healthy and infertile men

Capsule:
High numbers of diverse kinds of bacteria were present in the semen of both sperm donors and infertility patients. There were no significant differences between these two groups based on community composition.

Authors:
Dongsheng Hou, Ph.D., Xia Zhou, M.D., Xue Zhong, Ph.D., Matt Settles, Ph.D., Jessica Herring, B.S., Li Wang, B.S., Zaid Abdo, Ph.D., Larry Forney, Ph.D., Chen Xu, M.D., Ph.D.

Volume 100, Issue 5, Pages 1261-1269.e3, November 2013

Abstract:

Objective:
To explore potential causes of male infertility by determining the composition and structure of commensal bacterial communities in seminal fluids.

Design:
Microscopy of Gram-stained semen samples and classification of 16S rRNA gene sequences to determine the species composition of semen bacterial communities.

Setting:
Clinical andrology laboratory and academic research laboratories.

Patient(s):
Nineteen sperm donors and 58 infertility patients.

Intervention(s):
None.

Main Outcome Measure(s):
Classification of 16S rRNA gene sequences, clustering of seminal microbial communities, and multiple statistical tests.

Result(s):
High numbers of diverse kinds of bacteria were present in most samples of both sperm donors and infertility patients. The bacterial communities varied widely among subjects, but they could be clustered into six groups based on similarities in composition and the rank abundances of taxa. Overall, there were no significant differences between sperm donors and infertility patients. However, multiple statistical tests showed a significant negative association between sperm quality and the presence of Anaerococcus. The results also indicated that many of the bacterial taxa identified in semen also occur in the vaginal communities of some women, especially those with bacterial vaginosis, which suggests that heterosexual sex partners may share bacteria.

Conclusion(s):
Diverse kinds of bacteria were present in the human semen, but there were no significant differences between sperm donors and infertility patients. The presence of Anaerococcus might be a biomarker for low sperm quality.

  • Another study showing the diversity of bacteria in semen sample. It is important for the workup of leukospermia and not to over treat with antibiotics since semen culture is often not helpful in asymptomatic men.

  • Interesting study. However, in terms of practical significance, intercourse does not occur in a sterile environment. There are also normal bacteria colonizing the skin of the penis, distal urethra, and inside the vagina. It will be interesting to see if future studies into specific bacteria that cause infertility as suggested by this study (ie Anaerococcus) will come up with any significant findings.

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