Behavioral Ecology Vol. 14 No. 1: 40-47
© 2003 International Society for Behavioral Ecology
Do bacterial infections cause reduced ejaculate quality? A meta-analysis of antibiotic treatment of male infertility
Department of Evolution and Ecology, IB, University of Tromsø, 9037 Tromsø, Norway
Address correspondence to P.A. Skau. E-mail: philip{at}stud.ibg.uit.no.
Ejaculate quality may limit male reproductive success, and consequently, sperm quality is of importance. Spermatozoa are perceived as "non-self" by the immune system and are exposed to immunological attacks in the male reproductive tract. To reduce immunological reactions against their own sperm, males are dependent on the testis being an immunoprivileged site. Immunoprivilege is obtained by the blood-testis barrier and by local immunosuppression by androgens. Despite this testicular immunosuppression, an influx of leukocytes may occur in testes. The condition in which males have a heightened level of leukocytes in semen is called leukocytospermia, and it is associated with reduced fertility. As the ability of immunosuppression by androgens may depend on current intensities of infectious organisms in the extratesticular soma, only males with high parasite resistance may be able to bear the cost of immunosuppression and consequently produce high quality ejaculates. This issue is addressed by a meta-analysis on the effects of broad-spectrum antibiotic treatment of male leukocytospermia-associated infertility. The analysis showed that antibiotic treatment of leukocytospermic men, without diagnosed genital tract infections, resulted in a significant improvement of ejaculate quality, that is, an increase in ejaculate volume, sperm concentration, number of motile spermatozoa, and number of spermatozoa with normal morphology. Moreover, the amount of leukocytes in semen was also reduced. This suggests that broad-spectrum treatment targeted toward bacterial infections reduces the density of leukocytes in semen and, at the same time, improves the quality of ejaculates produced. Our results emphasize the importance of parasitic resistance and immunity as factors that cause variations in ejaculate quality.
Key words: antibiotic treatment, ejaculate quality, immunity, leukocytospermia, male infertility, meta-analysis, parasite resistance, sperm.
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