Staphylococcus saprophyticus and Escherichia coli: Tracking from sperm fertility potential to assisted reproductive outcomes

Optimization of the microbiological treatment of sperm for assisted reproductive technology (ART)

In ART,1 optimized sperm preparation could separate spermatozoa from potentially harmful germs and cells, improving sperm parameters. This study compares the outcome of a routinely used two-layer density gradient with a three-layer protocol in terms of sperm and microbiological parameters. According to the results, a three-layer protocol was more effective.

Successful pregnancy with intracytoplasmic sperm injection after bacterial contamination of embryo culture in in vitro fertilization: a case report

BACKGROUND

Bacterial infection of embryo culture medium is rare but may be detrimental. The main source of embryo culture contamination is semen. Assisted reproduction centers currently lack consensus regarding the methods for preventing and managing embryo culture infection. In our recent case, a successful pregnancy was achieved with intracytoplasmic sperm injection after failed conventional in vitro fertilization owing to bacterial contamination.

CASE PRESENTATION

We present a case report of two consecutive in vitro fertilization-intracytoplasmic sperm injection cycles with photo and video documentation of the bacterial growth. A 36-year-old Hungarian woman and her 37-year-old Hungarian partner came to our department. They had two normal births followed by 2 years of infertility. The major causes of infertility were a closed fallopian tube and asthenozoospermia. Bacterial infection of the embryo culture medium was observed during in vitro fertilization and all oocytes degenerated. The source was found to be the semen. To prevent contamination, intracytoplasmic sperm injection was used for fertilization in the subsequent cycle. Intracytoplasmic bacterial proliferation was observed in one of the three fertilized eggs, but two good-quality embryos were successfully obtained. The transfer of one embryo resulted in a successful pregnancy and a healthy newborn was delivered.

CONCLUSION

Intracytoplasmic sperm injection may be offered to couples who fail conventional in vitro fertilization treatment owing to bacteriospermia, as it seems to prevent infection of the embryo culture. Even if bacterial contamination appears, our case encourages us to continue treatment. Nevertheless, the development of new management guidelines for the prevention and management of bacterial contamination is essential.

Sperm interaction with bacteria induces the spontaneous acrosome reaction

Bacterial contamination in the semen deteriorates spermatozoa function. One mechanism through which this may occur is by inducing a premature form of the acrosome reaction (spontaneous acrosome reaction (sAR)) which has been shown to abrogate fertilization. To understand the mechanism by which bacteria affect sperm functions, we determined the effects of bacteria on sperm sAR and on other parameters involved in sperm capacitation. Sperm cells undergo biochemical changes in the female reproductive tract collectively called capacitation. Only capacitated sperm can undergo the physiological acrosomal exocytosis process near or on the oocyte, which allows the spermatozoon to penetrate and fertilize the egg. Bovine sperm incubated with the bacteria Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) or Pseudomonas aeruginosa (P. aeruginosa), revealed a sperm-bacteria interaction, however only E. coli and P. aeruginosa caused an increase in sperm sAR. This effect was seen only when the bacteria were present with the sperm during the full incubation under capacitation conditions but not when the bacteria were added to capacitated sperm. These results indicate that bacteria affect sperm during capacitation and not at the AR step. In addition, Ca²⁺ influx, protein kinase A, and protein tyrosine phosphorylation activities, three essential processes that promote capacitation, were inhibited by the bacteria. Moreover, increasing intracellular cAMP, which also occur during sperm capacitation, caused significant reverse of sAR induced by the bacteria.

Ejaculate for Microbiological Culture: To Wash or Not To Wash?

Bacteria can be associated with male infertility. Antibacterial substances (e.g., zinc-containing proteins, antimicrobial peptides) in ejaculates might impair the growth of bacteria in culture. We therefore wanted to test if removing antibacterial substances by washing the ejaculate could improve the detection of bacteria in culture. All ejaculates from patients ≥18 years old, which were obtained for routine diagnostics to assess male infertility were included in this study (no exclusion criteria were applied). Test samples were diluted with 2 mL sterile 0.45% saline, vortexed, and centrifuged (5 min; 7.5 × g). After the removal of 2 mL of the supernatant and resuspension, 10 μL of the pellet was used for aerobic and anaerobic culture. Control samples were cultured identically but without washing. Species identification was done with matrix-assisted laser desorption ionization-time of flight mass spectrometry. A total of 186 samples were included. The data set was stratified into five groups (Gram-negative rods [GNR], anaerobes [AN], Enterococcus spp. [EC], coagulase-negative staphylococci [CNS], and viridans streptococci [VS]). Compared to the control arm, the test arm revealed significant lower proportions for CNS (59.1% versus 44.6%, P < 0.01) and VS (53.8% versus 41.9%, P = 0.03). Similarly, slightly lower proportions of GNR (16.1% versus 15.1%, P = 0.89), AN (19.9% versus 17.2%, P = 0.5), and EC (25.3% versus 23.1%, P = 0.63) were observed. The medians of CFU were lower in test samples compared to the control samples (6.5 × 10³ versus 2.5 × 10³, P < 0.01) for any bacterial growth. Lower colony counts were also observed for individual bacterial groups. In conclusion, preculture washing of ejaculates results in a decrease in total bacteria count and culture-positive samples. IMPORTANCE This study compares two methods for processing ejaculate samples from men undergoing investigations for infertility. The method of sample washing and centrifugation was compared to the standard method of direct inoculation and culture. The study hypothesis was that preprocessing of samples may increase bacterial yield by removing bactericidal substances from semen. However, we found that washing ejaculate samples before microbiological culture did not improve the detection of bacteria and led to a reduction in colony counts.

Bacteriospermia and Male Infertility: Role of Oxidative Stress

Male infertility is one of the major challenging and prevalent diseases having diverse etiologies of which bacteriospermia play a significant role. It has been estimated that approximately 15% of all infertility cases are due to infections caused by uropathogens and in most of the cases bacteria are involved in infection and inflammation leading to the development of bacteriospermia. In response to bacterial load, excess infiltration of leukocytes in the urogenital tract occurs and concomitantly generates oxidative stress (OS). Bacteria may induce infertility either by directly interacting with sperm or by generating reactive oxygen species (ROS) and impair sperm parameters such as motility, volume, capacitation, hyperactivation. They may also induce apoptosis leading to sperm death. Acute bacteriospermia is related with another clinical condition called leukocytospermia and both compromise male fertility potential by OS-mediated damage to sperm leading to male infertility. However, bacteriospermia as a clinical condition as well as the mechanism of action remains poorly understood, necessitating further research in order to understand the role of individual bacterial species and their impact in male infertility.

Evaluation of the Presence of Bacterial and Viral Agents in the Semen of Infertile Men: A Systematic and Meta-Analysis Review Study

Objectives

Infections in the male genitourinary system with bacterial and viral agents may play a significant role in male infertility. These agents usually infect the urethra, seminal vesicles, prostate, epididymis, vas deferens, and testes retrograde through the reproductive system. A meta-analysis review study was performed to evaluate the presence of bacterial and viral agents in the semen of infertile men and its correlation with infertility.

Methods

Relevant cross-sectional and/or case-control studies were found by an online review of national and international databases (Web of Science, PubMed, Scopus, Science Direct, and Google scholar), and suitable studies were selected. A checklist determined the qualities of all studies. Heterogeneity assay among the primary studies was evaluated by Cochran’s Q test and I² index (significance level 50%). A statistical analysis was conducted using the Comprehensive Stata ver. 14 package (StataCorp, College Station, TX, United States).

Results

Seventy-two studies were included in this meta-analysis. Publication bias was compared with Egger’s test, and the impact of each research on overall estimate was evaluated by sensitivity analysis. In 56 studies, the rate of bacterial infections in the semen of infertile men was 12% [95% confidence interval (CI): 10–13]. Also, in 26 case-control studies, the association of infertility in men with bacterial infections was evaluated. The results show that the odds ratio of infertility in men exposed to bacterial infections is 3.31 times higher than that in non-infected men (95% CI: 2.60–4.23). Besides, in 9 studies that examined the prevalence of human papillomavirus (HPV), herpes simplex virus 1 (HSV1), herpes simplex virus 2 (HSV2), and herpes simplex virus 1-2 (HSV1-2) in infertile men, the frequency of these viruses was 15% (95% CI: 9–21). In 6 case-control studies, the association between human cytomegalovirus (HCMV), Cytomegalovirus (CMV), and HPV and male infertility was evaluated. The chance of male infertility due to exposure to these viruses was 2.24 times higher than those without exposure to these viruses (CI 95%: 1.9–4.52). The results show that the chance of infertility in men exposed to bacteria was significantly higher than that in the uninfected population.

Conclusion

This meta-analysis showed that viral and bacterial infections are a risk factor and could impair male fertility potential. Moreover, our study supports the hypothesis that bacterial and viral infections of the genital tract correlate positively with impairment of sperm quality in the male population.

The Impact of Bacteriocenoses on Sperm Vitality, Immunological and Oxidative Characteristics of Ram Ejaculates: Does the Breed Play a Role?

Bacterial contamination of semen is an often overlooked, yet important, factor contributing to decreased sperm vitality. Understanding the impact of bacterial presence on sperm structural integrity and functional activity may assist the development of effective strategies to prevent, or manage, bacteriospermia in the breeding practice. The aim of this study was to describe the bacterial profiles of ram semen (n = 35), and we also focused on the associations between bacteriospermia, sperm structure, and function, as well as oxidative and inflammatory characteristics of semen. For a better insight, the samples were divided into three groups, according to the breeds used in the study: native Wallachian (NW), improved Wallachian (IW), and Slovak dairy (SD) breeds. The results showed a significantly lower motility and membrane integrity in the NW group in comparison to the IW and SD groups, which was accompanied by a significantly higher concentration of leukocytes, increased reactive oxygen species (ROS) generation, and subsequent oxidative insults to the sperm lipids and proteins. Accordingly, the NW group presented with the highest bacterial load, in which Staphylococcus and Escherichia were the predominant representatives. The Pearson correlation analysis uncovered positive relationships amongst the bacterial load and leukocytospermia (r = 0.613), the extent of lipid peroxidation (r = 0.598), protein oxidation (r = 0.514), and DNA fragmentation (r = 0.638). Furthermore, positive correlations were found between the bacterial load and pro-inflammatory molecules, such as the C-reactive protein (r = 0.592), interleukin 1 (r = 0.709), and interleukin 6 (r = 0.474), indicating a possible involvement of the immune response in the process of bacteriospermia. Overall, our data indicate that ram semen quality may be equally affected by the bacterial load and diversity. Furthermore, we can assume that the presence of bacteria in ejaculates triggers inflammatory processes, causes ROS overproduction, and, thereby, contributes to alterations in the sperm structure, while at the same time compromising the fertilization ability of male gametes.