How does a man’s seminal microbiome alter a woman’s vaginal microbiome?

There is very little research on the microbiome of semen.  We know that it is not sterile, and some scientists think that some of the bacteria found in semen may be involved in male fertility issues.  However, there is still a lot of research to be done in this area.  Even less is known about how the seminal microbiome influences the vaginal microbiome after sex.  Some research has suggested that specific sexual partners can cause bacterial vaginosis (BV), however the mechanisms for this are unclear.  It is suggested that perhaps the penile and seminal microbiome being transferred to the vagina during sex could cause this, although research has not confirmed these hypotheses.  Researchers from Estonia tried to answer these questions, and studied just how the vaginal and seminal microbiomes change before and after sex.  They published the results of their findings last week in Research in Microbiology. 

The scientists measured the seminal and vaginal microbiomes before and after sex for 23 couples who had sought help for infertility but were otherwise healthy.  They learned that the seminal microbiome, while containing much fewer bacteria, was actually more diverse than the vaginal microbiome.  Still though, each shared many of the same bacteria.  These included Lactobacillus, Veillonella, Streptococcus, Porphyromonas and Atopobium.  Interestingly, Gardnerella vaginalis, a bacterium highly implicated with BV, was found more frequently in women who had sex with men whose semen contained leukocytes, itself a phenotype associated with infertility.  While most of the women’s microbiomes did not shift after sexual intercourse, four of them did.  In these women a decrease in Lactobacillus occurred, and a decrease in Lactobacillus has also been highly implicated in BV.

While this study was preliminary, it marks some of the first research on the dynamics of the seminal and vaginal microbiome during sex.  The scientists suggest that the microbiome may be very important to fertility issues, and at the AMI we would not be surprised to learn that it is involved in at least some causes of infertility.  In the near future we will be devoting an entire podcast to the vaginal microbiome, and interviewing Jacques Ravel, a world leader in this field.  If you have any relavent questions and would like us to ask them on the podcast please call 518-945-8583 and leave your question on the voicemail.

Mouth diseases and tooth loss may be caused by oral microbiome alterations

Chronic periodontitis is a prevalent inflammatory disease of the tissue around and supporting the teeth and is the leading cause of tooth loss in the United States. Scientists at the University of Florida recently published a study in Applied and Environmental Microbiology that studied the oral microbiome of 25 healthy individuals and 25 individuals with chronic periodontitis, in order to determine if there are any consistent microbial differences between the groups.

In the study, they found that patients with periodontal disease had an altered oral microbiome with microbial communitites that were more homogeneous than healthy individuals’.  They were able to identify two specific groups of bacteria, Fusobacterium and Porphyromonas, that were associated with periodontitis and another two groups of bacteria, Rothia and Streptococcus, that were prevalent in the majority of the healthy sites without periodontitis.  The scientists also identified several genes that were involved with various biological activities that were enriched in the oral microbiome of healthy individuals.

This study provides more insight into the possible microbial causes of chronic periodontitis, which is common among adults in the United States. While this study is limited because of its small sample size and its lack of diversity among severity of chronic periodontitis disease, it is still a great starting point for further inquiry into the disease. The scientists also compared their work to previous studies utilizing Human Microbiome Project (HMP) participants, though the HMP only included healthy individuals and excluded individuals with periodontal disease.  Further research could lead to the discovery of better ways to both treat and prevent the disease by altering the microbial communities of our mouth.