A study published in the Journal of Assisted Reproduction and Genetics earlier this month, provides an in-depth look at the microbiome of human sperm utilizing RNA sequencing with sufficient sensitivity to identify contamination and pathogenic bacterial colonization.
"We show that non-targeted sequencing of human sperm RNA has the potential to provide a profile of micro-organisms (bacteria, viruses, archaea)," said senior author Stephen Krawetz, Ph.D., from Wayne State University. "This information was recovered from the data typically cast aside as part of routine nucleic acid sequencing. The enhanced sensitivity and specificity of the sequencing technology as compared to current approaches may prove useful as a diagnostic tool for microbial status as part of the routine assessment as we move toward personalized care."
The researchers collected 85 semen samples, isolated the sperm RNA and subjected it to RNA sequencing. First author Grace Swanson, Ph.D., discovered a sample with an abnormally high level of microbial sequences. After taking a closer look, the sample was found to contain a considerable amount of Streptococcus agalactiae bacteria. A leading cause of neonatal infection during pregnancy and post-delivery linked to significant mortality rates in premature births, this bacteria can also be life-threatening in adults, particularly the elderly.
The current method for testing the male reproductive tract microbiome relies on culturing samples. This, the study reported, can be limiting because the majority of pathogens cannot be cultured. The costs of RNA sequencing have dropped dramatically and continue to decrease, providing a more complete picture of the human biome.
"Given the recent increase and severity of Streptococcus agalactiae infection, as well as others in adults, neonates and newborns, non-targeted human sperm RNA sequencing data may, in addition to providing fertility status, prove useful as a diagnostic for microbial status," Dr. Krawetz said.