Bacterial Infection of the reproductive tract organs can impair the production of sperm or cause scarring and blockage of the tubules that transport sperm, causing infertility. Bacteria can infect various organs of the male reproductive tract including the testis (causing orchitis), the epididymis (causing epididimitis) and the prostate (causing prostatitis). Infection of the testis can shut down the production of sperm by blocking the tiny testicular tubules in which sperm are produced called seminiferous tubules.
Freshly produced sperm are temporarily stored in the epididymis, an organ alongside the testis consisting of coiled sperm ducts in which sperm undergo final maturation as they slowly move through the sperm ducts. Infections in the epididymis may interfere with the proper maturation of sperm and can block sperm transport. Because the prostate produces a large portion of the fluid in the ejaculate, infection in the prostate may block the release of fluid from the prostate, reducing the volume of ejaculate.
Finding bacteria in the semen is relatively common and is not enough to diagnose infection because bacteria can appear in the semen due to contamination of the sample during collection. Bacteria present on the skin such as staphylococcus and streptococcus are common sources of contamination. Semen may become contaminated with bacteria if the man has a urinary tract infection. E.coli from the gastrointestinal tract may also contaminate semen in the ejaculate. The World Health Organization (WHO) defines infection of the semen as the presence of greater than 1000 bacteria per ml (about a teaspoon) of semen. The presence of very high numbers of white blood cells in the semen (greater than one million per ml) can also signal that an infection is present. To diagnose infection, a
sample of semen is cultured in the lab to see which bacteria actually grow out in colonies on culture plates.