Objective: To investigate bacterial infection and the distribution of different bacterial species in the donor semen and the influence of different bacterial counts on semen quality.
Methods: Bacterial colonies in the semen samples from 1 126 donors were counted with the Synbiosis Protocol 3 Automatic Colony Counter and the bacterial species with a colony count ≥10⁴ cfu/ml identified with the VITEK2 Compact Automatic Biochemical Analyzer. The Makler Sperm Counting Board was used to examine the semen quality of the semen samples with a colony count = 0 cfu/ml (n = 22, group A), those with a colony count <10⁴ cfu/ml (n = 22, group B) and those with a colony count ≥10⁴ cfu/ml (n = 22, group C). Univariate analysis was employed for comparison of semen quality among different groups.
Results: Among the 1 126 donor semen samples cultured, 5 (0.44%) showed mixed bacterial contamination and 993 (88.58%) showed none but with growth of a certain species of bacteria, 2.22% (22/993) with a colony count ≥10⁴ cfu/ml, mainly including Streptococcus bovis, tiny bacilli, Staphylococcus epidermis, and Staphylococcus aureus, among which gram-positive and gram-negative bacteria accounted for 95.45% (21/22) and 4.54% (1/22), respectively. Compared with group A, groups B and C manifested significantly reduced total sperm count (［567.5 ± 327.6］ vs ［421.9 ± 155.9］ and ［389.9 ± 110.6］ × 106 per ejaculate, P <0.05) and percentage of progressively motile sperm (［65.0 ± 6.5］ vs ［61.0 ± 3.5］ and ［61.6 ± 4.3］ %, P <0.05). There were no statistically significant differences among the three groups in the semen liquefaction time, semen pH value, total sperm motility or percentage of morphologically normal sperm (P > 0.05). Of the 284 randomly selected semen samples, 34 (11.97%) were found positive for Ureaplasma urealyticum (UU) and no significant difference was observed in the semen quality between the UU-positive and UU-negative samples (P> 0.05).
Conclusions: The bacteria-positive rate is high in the donor semen and the bacterial species are varied, mainly including gram-positive bacteria. Semen quality is reduced with the increased number of bacterial colonies.
目的: 通过对捐精者精液细菌培养、感染不同菌落数的精液质量检测，了解捐精者精液细菌感染率和菌种分布情况、不同菌落数细菌感染对精液质量的影响。 方法: 对1 126例捐精者精液样本进行细菌培养，用Synbiosis全自动菌落计数仪对样本进行菌落计数,并用梅里埃VITEK2 Compact全自动微生物生化鉴定仪对菌落数≥10⁴cfu/ml的样本进行菌种鉴定；按不同菌落数从1 126例精液样本中分别选取22例菌落数<10⁴cfu/ml和22例菌落数≥10⁴cfu/ml的精液样本，使用Makler精子计数板进行人工精液质量检测,并与对照组（未检出细菌，菌落数=0 cfu/ml）的精液质量进行比较。结果: 1 126例精液样本细菌培养中，杂菌污染5例，占0.44%（5/1 126），未被杂菌污染的样本中有细菌生长993例，占88.58%（993/1 121），菌落数≥10⁴cfu/ml的精液样本有22例，占2.22%（22/993），以牛链球菌（Streptococcus bovis）为主，极小棒状杆菌（Tiny bacilli）、表皮葡萄球菌（Staphylococcus epidermis）、金黄色葡萄球菌（Staphylococcus aureus）次之，其中革兰阳性菌（G⁺菌）95.45%（21/22），革兰阴性菌（G⁺菌）4.54%（1/22）。菌落数#8805;10⁴cfu/ml和菌落数<10⁴cfu/ml的精子总数(×106/1次射精)（389.9±110.6、421.9±155.9）和精子前向运动(PR,%)（61.6±4.3、61.0±3.5）与对照组（分别为567.5±327.6、65.0±6.5）比较有显著性差异（P<0.05），精液液化时间(min)、精液pH值、精子总活力（PR+NP,%）和正常形态精子（%）与对照组比较无显著性差异（P>0.05）。随机对284例精液样本进行解脲脲原体（UU）检测，UU阳性34例，占11.97%。同时将UU阳性与UU阴性的精液质量作比较发现，无显著性差异（P﹥0.05）。结论: 精液细菌培养阳性率占88.58%，细菌种类较多，以G+菌为主。同时，随着菌落数的增多，精液质量逐渐降低。.
Keywords: bacteria; donor sperm; infection; semen quality.