Andrology, Women's Endocrinology and Gender Incongruence Unit, Careggi Hospital, 50139, Florence, Italy.
Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, 50134, Florence, Italy.
Sci Rep. 2021 Sep 28;11(1):19177. doi: 10.1038/s41598-021-98710-5.
Male genitourinary tract (MGT) bacterial infections are considered responsible for 15% of male infertility, but the mechanisms underlying decreased semen quality are poorly known. We evaluated in vitro the effect of strains of Gram-negative uropathogenic species (two E.coli strains, three K. pneumoniae strains, P. aeruginosa and E. cloacae) on motility, viability, mitochondrial oxidative status, DNA fragmentation and caspase activity of human spermatozoa. All strains, except P. aeruginosa, reduced significantly sperm motility, with variable effects. Sperm Immobilizing Factor (SIF) was largely responsible for deteriorating effects on sperm motility of E. coli strains since they were completely reverted by knockout of SIF coding recX gene. Sequence alignment for RecX showed the presence of high homologous sequences in K. pneumoniae and E. cloacae but not in P. aeruginosa. These results suggest that, in addition to E.coli, other common uropathogenic Gram-negative bacteria affect sperm motility through RecX products. In addition to sperm motility, the E. coli strain ATCC 35218 also affected sperm viability, and induced caspase activity, oxidative stress and DNA fragmentation suggesting an interspecies variability in the amount and/or type of the produced spermatotoxic factors. In general, our results highlight the need for a careful evaluation of semen infections in the diagnostic process of the infertile man.
男性泌尿生殖道（MGT）细菌感染被认为占男性不育的 15%，但其导致精液质量下降的机制尚不清楚。我们评估了革兰氏阴性尿路致病性菌（两种大肠杆菌菌株、三种肺炎克雷伯菌菌株、铜绿假单胞菌和阴沟肠杆菌）对人精子活力、活力、线粒体氧化状态、DNA 碎片化和半胱天冬酶活性的体外影响。除了铜绿假单胞菌外，所有菌株都显著降低了精子活力，其影响程度不同。精子固定因子（SIF）是导致大肠杆菌菌株精子活力恶化的主要原因，因为敲除 SIF 编码 recX 基因后，其作用完全逆转。RecX 的序列比对显示，肺炎克雷伯菌和阴沟肠杆菌中存在高度同源序列，但铜绿假单胞菌中不存在。这些结果表明，除了大肠杆菌，其他常见的尿路致病性革兰氏阴性菌也通过 RecX 产物影响精子活力。除了精子活力外，大肠杆菌菌株 ATCC 35218 还影响精子活力，并诱导半胱天冬酶活性、氧化应激和 DNA 碎片化，这表明在产生的精子毒性因子的数量和/或类型方面存在种间变异性。总的来说，我们的研究结果强调了在不育男性的诊断过程中需要仔细评估精液感染。
