Microbiota of semen samples with normozoospermia: analysis of real-time PCR data

The analysis of semen microbiota is difficult due to the lack of established criteria for interpretation of microbiological tests. The aim of the study was to determine the stable clusters of semen microbiota analyzed by real-time PCR in samples with normozoospermia. Semen samples of 227 men with normal spermiograms were included in the study. The quantity of total bacterial DNA and at least one group of microorganisms was more than 103 GE/ml in 107 (41.7%) samples. Four stable microbiota clusters with the prevalence of a specific microorganism group were distinguished in these samples: obligate anaerobes (OA) cluster (proportion in the centroid — 81.1%); Lactobacillus spp. cluster (proportion in the centroid — 64.3%); gram-positive facultative anaerobes (GPFA) cluster (proportion in the centroid — 92.5%); Enterobacteriaceae/Enterococcoccus (EE) cluster (proportion in the centroid — 80.8%). The clusters were ranked by frequency of occurrence: OA cluster was the most prevalent (43 (40.2%) of 107), second-most frequent were GPFA-cluster (27 (25.2%)) and Lactobacillus-cluster (22 (20.6%)). EE-dominated cluster was found in 15 (14.0%) cases.