Is the sperm bacterial ratio a determining factor in impairment of sperm motility: an in-vitro study in man with Escherichia coli.

The effects of urogenital infection on male fertility are controversial. The object of this study was to assess whether contact between E. coli, one of the bacteria encountered most frequently in semen cultures, and sperm was involved in decreasing motility of the sperm. Sperm from healthy donors were therefore incubated at two concentrations (1.10(7) and 4.10(7) ml-1) with bacteria (10(4) and 10(6) bacteria ml-1 respectively). Sperm motility was assessed as a function of time. The endotoxin effect was also evaluated. Aliquots of the sperm were used as controls. The motility of a population of 10(6) sperm ml-1 was reduced significantly more by the presence of 10(6) ml-1 E. coli than a sperm population four times more numerous. Since the endotoxin had no effect on sperm motility, it is possible this phenomenon is due to bacterial adherence to the sperm. From this study, it is therefore probable that the presence of E. coli in semen decreases sperm motility, but that this depends on the sperm:bacterial ratio ml semen-1.