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.

Semen microbiota: cluster analysis of real-time PCR data

To this day semen microbiota is still poorly understood, and clinical significance of detecting specific microorganism groups has not been clearly determined. The aim of this work was to conduct cluster analysis of semen microbiota detected using real-time PCR. 634 semen samples of reproductive age men were analyzed using the Androflor kit. Microbial DNA in the quantity of no less than 103 GE/ml was detected in 460 samples (72.5%). From 1 to 14 microorganism groups were detected in 350 samples (55.2%) in the quantities that exceeded the threshold values (the detection rate of specific groups: 3.3–21.0%). In these 350 samples 4 stable microbiota clusters were determined. Each of the clusters was characterized by the prevalence of a specific microorganism group: obligate anaerobes (cluster 1; n = 172; detection rate — 49.1%), Lactobacillus spp. (cluster 2; n = 78; detection rate — 22.3%), gram-positive facultative anaerobes (cluster 3; n = 62; detection rate — 17.7%), Enterobacteriaceae / Enterococcoccus (cluster 4; n = 62; detection rate — 10.9%). Cluster 1 was less stable and was characterized by the larger species diversity compared to other clusters.

Diagnostic significance of Lactobacillus spp. identification in ejaculate

Popularization of the real-time polymerase chain reaction method (RT-PCR), which is a trend of the recent years, allowed to significantly expand of the range of microorganisms that can be detected in the genitourinary tract of men. Moreover, the available picture of the microbiome's bacterial component structure became more detailed. Lactobacillus spp. remains one of the least studied groups of microorganisms. Treating patients with reproductive disorders, the authors have accumulated clinical experience demonstrating the possible relationship between presence of Lactobacillus spp. in the ejaculate and changes in the level of sex hormones and the key values registered with a spermogram. This study aimed to compare the levels of luteinizing hormone, follicle-stimulating hormone, testosterone, estradiol, prolactin, progesterone, and sex hormone binding globulin (SHBG) in blood serum and changes in spermogram values in 210 men with and without Lactobacillus spp. detected in their ejaculate. The treatment group included 105 men whose ejaculate had Lactobacillus spp. in the amount of (Lg) ≥ 103, as detected by RT-PCR. The control group included 105 men whose ejaculate did not have Lactobacillus spp. detected; the microbiome's bacterial component structure of their ejaculate was normal. Compared to the control group, treatment group had hormonal disorders registered more often: abnormal levels of three or more hormones (p = 0.04), hyperestradiolemia (p = 0.05), increased level of SHBG (p = 0.01). It was established that the presence of Lactobacillus spp. in the ejaculate of treatment group participants is associated with oligoastenoteratozoospermia (p < 0.01), decreased concentration of spermatozoa (p = 0.01), their decreased motility (p < 0.01) morphology abnormalities (p < 0.01). Thus, the presence of Lactobacillus spp. in the ejaculate can be interpreted as an additional marker of hormonal imbalance and fertility dysfunction in men.