Significance of Positive Semen Culture in Relation to Male Infertility and the Assisted Reproductive Technology Process

Joshua S. Jue, Ranjith Ramasamy


Transl Androl Urol. 2017;6(5):916-922. 

In This Article

General Bacteria

Enterobacteriaceae is a family of gram negative bacteria that includes organisms such as E. coli, Klebsiella, Salmonella, Proteus, and Pseudomonas. These bacteria are associated with epididymitis, orchitis, and prostatitis, suggesting that they may have a role in infertility.[14] Although few mechanisms have been proposed for Enterobacteriaceae, E. coli have been found to have a special effect on sperm motility and acrosomal function.[9]

Gram positive cocci include Enterococci, Streptococci, and Staphylococci. Prostatitis and epididymitis have been associated with these organisms, suggesting that they may have a role in infertility too.[14] In in vitro studies, gram positive cocci have demonstrated a negative influence on sperm morphology, probably mediated by its virulence factor hemolysin.[9] These organisms are very prevalent in semen cultures and have even been found to be the most common bacteria.[19] In one retrospective study, 80/342 cultures grew more than 10,000 colony forming units of Enterococci.[19] However, this study did not find that pregnancy rates significantly differed with the semen culture positivity before or during the IVF attempt.[19] Pregnancy rates also did not significantly correlate with the successful treatment of the semen culture prior to the IVF attempt.[19] Despite the potential for inflammatory disease, Enterobacteriaceae and gram positive cocci do not appear to have significant correlation with male infertility.

One retrospective study found significant sperm quality differences between fertile and infertile men within each bacterial positive group, but no significant differences between fertile men with bacteria positive and negative semen cultures.[9] Within each bacteria positive group, the mean sperm concentration was significantly lower among infertile men, but was always higher than the WHO normal value of 20×106.[9] This suggests that potential differences in sperm composition by the presence of general bacteria may not have clinical significance. This same study also excluded 171/417 males because cultures contained two or more bacteria species or a non-significant bacteria colony count.[9] The extent of excluded cultures highlights the potential burden of general bacteria as urethral flora and/or contamination, as well as the possible selection biases from differing reproduction times between bacterial species.