RESUMO
OBJECTIVE: To investigate the distribution of pathogenic bacteria in donor semen and the effect of bacterial infection on semen quality. METHODS: We performed bacterial culture on and counted the bacterial colonies (BC) in the semen samples collected from 4 897 sperm donors from 2008 to 2018 and divided them into groups A (BC <104 cfu/ml, n = 4 229), B (BC ≥104 cfu/ml, n = 150) and C (BC = 0 cfu/ml, n = 518). Using the biochemical reaction system of the French Biological Merry Emmanuel Company, we identified the bacterial species in group B, subjected all the semen samples to SCA computer assisted semen analysis, and compared the semen quality among different groups. RESULTS: In the 4 897 semen samples, hybrid bacterial contamination was found in 6 (0.12%) and non-hybrid bacteria in 4 379 (89.42%), including 150 (3.43%) in group B. In the semen samples with BC ≥104 cfu/ml, Gram-negative (Gï¼) bacteria were observed in 104 (69.33%), mainly including Escherichia coli, followed by Proteusbacillus vulgaris and Enterobacteria, Gram-positive cocci (G+) in 39 (26.00%), Gï¼ bacteria in 4 (2.67%) and Neisseria gonorrhoeae in 3 (2.00%). Compared with group C, groups A and B showed remarkably reduced total sperm count (P < 0.05) and percentage of progressively motile sperm (P < 0.05) but no statistically significant differences in the semen liquefaction time, semen PH value, total sperm motility or the percentage of morphologically normal sperm (P > 0.05). CONCLUSIONS: Bacterial culture of donor semen revealed a positive rate of 89.42% and varied the bacterial species, mainly including Gï¼ bacteria. And the semen quality decreased with the increase of bacterial colonies.