Bacterial Infection of the Male Reproductive System Causing Infertility

[madman]

Highlights

 Bacterial infections represent good candidates to explain the causes of idiopathic infertility among different populations.

 Bacterial infections can affect different sites of the male reproductive tract and different stages of Spermatozoa development, maturation, and transport.

 There is ample evidence to blame different kinds of bacteria such as Escherichia coli, Chlamydia trachomatis, Ureaplasma, Mycoplasma, and Staphylococcus aureus for male infertility.

 Escherichia coli, Chlamydia trachomatis, Ureaplasma, Mycoplasma, and Staphylococcus aureus negatively affect sperm parameters, especially sperm integrity, motility, and morphology that would significantly decrease the fertility potential among men.

 Lack of scientific information concerning the underlying mechanism and significant role of some pathogenic bacteria such as N. gonorrhoeae, E. faecalis, and G. vaginalis in the reproductive system leaves more room for confusion and warrant more attention.


Abstract

Bacterial infections play a disruptive and hidden role in male reproductive failure. Different kinds of bacteria are often able to interfere with reproductive function in both sexes and lead to infertility. In this study, to further evaluate the role of bacterial infections in male reproduction we provided an extensive overview of so far researches investigating the effects of bacterial infections on male fertility. We searched Medline, PubMed, Scopus, and Google scholar databases to identify the potentially relevant studies on bacterial infections and their implications in male infertility. All the bacteria included in this article have negative effects on the male reproductive function; however, there is ample evidence to blame bacteria such as Escherichia coli, Chlamydia trachomatis, Ureaplasma, Mycoplasma, and Staphylococcus aureus for reduced fertility and deterioration of sperm parameters. More studies are needed to clarify the molecular mechanisms by which different bacteria exert their detrimental effects on the male reproductive system. Getting more insight into probable mechanisms would significantly facilitate the production of new, advanced, and effective remedies in the future. In view of all evidence, we strongly suggest increasing awareness among people and considering screening programs for patients seeking fertility both to avoid transmission and to improve fertility outcomes among them.

Conclusion

Bacterial infections are considered to be important etiological factors for male infertility. Different bacteria by negatively affecting the spermatogenesis process, sperm functions, and/or seminal tracts, prostate, and urethra may increase fertility problems among men. This review summarizes current knowledge regarding the different sorts of atypical, anaerobic, and aerobic bacteria disturbing semen quality and explains their possible role in male fertility which can be induced through multiple pathophysiological mechanisms. In this study, the significant effects of different bacteria on male infertility along with the sites of infection were summarized in simple tables and discussed. Every bacterium that affects fertility was reported to disturb spermiogram and to be involved in male reproductive failure. However, there is ample evidence to blame bacteria such as Escherichia coli, Chlamydia trachomatis, Ureaplasma, Mycoplasma, and Staphylococcus aureus for reduced fertility and deterioration of sperm parameters with more certainty. Although so far investigations have provided a great amount of information on the possible role of different bacterial infections in male infertility, there is a lack of scientific information concerning the underlying mechanism and true impacts of some pathogenic bacteria including N. gonorrhoeae, E. faecalis, and G. vaginalis on the male reproductive system which leaves room for confusion. Asymptomatic infections, associated with recurrent and latent infections, are the major challenges to the control of infertility. Increasing awareness among populations, proper sanitation, and proper precaution is the best approaches that can be considered to prevent their transmission and inhibit their prevalence among people. Understanding the true impacts of these pathogens and getting more insight into their underlying pathophysiological mechanisms would significantly pave the way for identifying suitable biomarkers and production of new treatment strategies in the future that would minimize the risks of bacterial infections on male reproductive conception.

 

[madman]

Figure 2. Mitochondrial dysregulation and ROS leakage from the inner mitochondrial membrane that would affect acrosomal reaction and sperm function negatively. If the ROS production exceeds concentrations of antioxidants in the spermatozoa, oxidative stress occurs. Increases levels of ROS damage the inner and outer mitochondrial membranes and induce premature capacitation that would affect acrosomal morphology and function; hence, impact the fertilizing capacity of human spermatozoa significantly. ROS in pathogenic bacteria such as E. coli, Mycoplasma, Chlamydia, streptococci, staphylococci, and Ureaplasma leads to apoptosis and breakdown of the mitochondrial membrane. Both superoxide (O2 .– ) and the hydroxyl radical (OH.– ) are toxic to cells and cause chromosome deletions, dicentrics, and sister chromatid exchanges.

 

[madman]

Figure 3. A summary of major causative pathogens, their effects on male infertility, and their loci of infection

 

[madman]

Figure 4. Different parts of sperm structure and the impact of different bacteria on these regions. ѱ indicates the impact of the mentioned bacteria on the neck region and † shows the impact of the pathogen on the acrosomal regions.