Aim： To study the influence of enterococci on human sperm membrane in vitro. Methods： Ejaculated human sperm were artificially infected with β-hemolytic or non-β-hemolytic enterococci at the bacteria： sperm ratio of 50：1 at 37℃. 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 β-hemolytic enterococci had lower HOS scores compared with non-β-hemolytic strains or uninfected control （P 〈 0.01）. The HOS test scores of sperm infected with β-hemolytic enterococci increased in the presence of phosphatidylcholine, an inhibitor of hemolysin. Non-β-hemolytic strains showed no significant difference in swelling rate, compared with the control group （P 〉 0.05）. It was shown by electron microscopy that β-hemolytic enterococci caused significant rupture of human sperm membrane. Conclusion： β-hemolytic enterococci caused human sperm membrane injury, and might be mediated by the hemolysin of enterococci.
