Research in Medicine

Background and aim: given the high prevalence of bacterial infections, particularly the E.coli in the semen of infertile men compared to fertile men and according to the controversial reports on the association of E.coli with male infertility, herein, the prevalence of this bacterium in the semen of infertile men and its possible association with parameters determining sperm fertility was evaluated.

Methods: In this case-control study and in a convenient sampling manner in 2014, semen specimens were collected from infertile and fertile men and were cultured on eosin methylene blue medium, and then, gram staining and biochemical tests were used to identify the E.coli bacteria. Sperm morphology and motility and other related parameters such as; fast, slow and non-progress motility was investigated according to the World Health Organization protocol. Finally, the sperm characteristics were compared between fertile and infertile E.coli-positive groups.

Results: the prevalence of E.coli in the semen of the infertile group was significantly higher than that in the fertile group (P <0.001). Also, there was statistically significant differences between fertile and infertile E.coli-positive men in terms of mean age, percentage of normal sperm morphology and all the characteristics of sperm motility (P <0.01).

Conclusion: despite the high prevalence of E.coli bacteria in the semen of the infertile compared to the fertile men, it seems that this bacterium is not responsible for alterations in morphology and motility properties of sperm. However, it suggested that in individuals with E.coli infection, along with increasing the age, the association between this bacterium and sperm quality becomes much more tangible.