The effect of temperature on sperm motility. II. Is bacterial growth a factor?

The previous demonstration that sperm kept at body temperature (37 degrees C) had a marked deterioration in motility accompanied by an overgrowth of bacteria in the semen and a concomitant decrease in pH led to this study to test the hypothesis that the decrease in motility was caused by the bacteria or by bacterial alteration of seminal pH. Semen specimens from fertile prevasectomy patients with and without added antibiotics were maintained at 20 degrees C and 37 degrees C and evaluated at 3, 12, and 18 hours after collection. There was still a significant deterioration in spermatozoal motility in the samples kept at 37 degrees C even when bacterial growth and change in pH were prevented by buffered antibiotics. Although the decrease in spermatozoal motility at body temperature may in part be attributed to bacterial growth or the products of bacterial metabolism, clearly another factor is present related to time and temperature and independent of the presence of bacteria.