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Objective: To assess the in vitro effect of three bacterial isolates (Escherichia coli, serotype O75:HNT, Staphylococcus haemolyticus, and Bacteroides ureolyticus) and/or leukocytes on sperm motility, subcellular changes in sperm plasma membranes, and sperm fertilizing potential., Design: An in vitro model of semen bacterial infection., Setting: Basic research laboratory., Patient(s): Healthy normozoospermic volunteers and healthy blood donors., Intervention(s): None., Main Outcome Measure(s): Sperm plasma membrane stability was evaluated with a LIVE/DEAD Sperm Viability Kit and with the merocyanine 540 (M540) test both performed using flow cytometry. An oxiSelect TBARS Assay Kit was used for quantitative measurement of malondialdehyde content. Functional ability of spermatozoa was assessed by hypo-osmotic swelling (HOS) test and sperm penetration assay (SPA)., Result(s): The incubation of sperm with bacteria and/or leukocytes was associated with the reduction of their fertilizing potential demonstrated in both the HOS test and SPA, and this effect can be considered as a natural consequence of diminished motility and sperm membrane injury of lipid bilayers. Bacteroides ureolyticus demonstrated the most significant detrimental effect on sperm structure and function., Conclusion(s): Sperm motility and lipid sperm membrane status might be the earliest and the most sensitive indicators of sperm damage with negative consequences for male factor fertility, which can be attributed to both bacteria and leukocytes action., (Copyright © 2014 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.)

Objective: To assess the in vitro effect of five bacterial strains isolated from semen samples (Escherichia coli, Staphylococcus haemolyticus, Streptococcus oralis, Bacteroides ureolyticus, and Ureaplasma urealyticum) on reactive oxygen intermediate (ROI) release and lipid sperm membrane peroxidation in the coincubated suspensions of white blood cells (WBC) with spermatozoa., Design: An in vitro model of semen infection., Setting: Basic research laboratory., Patient(s): Healthy normozoospermic volunteers and healthy blood donors., Intervention(s): None., Main Outcome Measure(s): Chemiluminescent assay was used to evaluate ROI generation by WBC. Malondialdehyde (MDA) concentration was determined in sperm lysates using high-performance liquid chromatography., Result(s): Of the bacterial strains tested, B. ureolyticus, S. haemolyticus, and E. coli caused the greatest damage to sperm membrane lipids. An increase in MDA levels in sperm lysates was a natural consequence of bacteria-induced ROI generation. The WBC usually enhanced harmful activity of the infectious agent toward the cell membranes., Conclusion(s): The harmful effect of bacteria on spermatozoa depends on the type and species of microorganisms invading, colonizing, or infecting the male genital tract and is associated with the accompanying oxidative stress. The presence of leukocytes in semen appears to be the additional factor enhancing the sperm lipid membrane peroxidation, which may affect the fertility status.