Influence of enterococci on human sperm membrane in vitro.

AIM To study the influence of enterococci on human sperm membrane in vitro. METHODS Ejaculated human sperm were artificially infected with beta-hemolytic or non-beta-hemolytic enterococci at the bacteria: sperm ratio of 50:1 at 37 degrees . Sperm membrane integrity was examined after incubation for 1, 3 and 5 h by hypoosmotic swelling (HOS) test and electron microscopy. RESULTS Sperm infected with beta-hemolytic enterococci had lower HOS scores compared with non-beta-hemolytic strains or uninfected control (P < 0.01). The HOS test scores of sperm infected with beta-hemolytic enterococci increased in the presence of phosphatidylcholine, an inhibitor of hemolysin. Non-beta-hemolytic strains showed no significant difference in swelling rate, compared with the control group (P > 0.05). It was shown by electron microscopy that beta-hemolytic enterococci caused significant rupture of human sperm membrane. CONCLUSION Beta-hemolytic enterococci caused human sperm membrane injury, and might be mediated by the hemolysin of enterococci.