Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
J Dairy Sci. 2010 Dec;93(12):5818-30. doi: 10.3168/jds.2010-3550.
Escherichia coli are believed to be associated with postpartum metritis and endometritis but their role in the pathogenesis of both diseases is still undefined. In this study, uterine swabs for E. coli isolation were collected from 374 lactating Holstein cows housed on 4 commercial farms near Ithaca, New York. A total, 125 of 374 cows (33.4%) were positive for E. coli culture. Standard multiplex PCR protocols were used to screen the isolates for the presence of 32 virulence factor genes. Cows that had twin parturition were 4.4 times more likely to have intrauterine E. coli contamination than those that gave birth to single live female calves. Stillborn parturition and birth of single live male calves also increased the odds of intrauterine contamination by E. coli (3.7- and 1.6-fold, respectively) compared with birth of live female calves. Six virulence factors, common to extraintestinal and enteroaggregative E. coli, were found to be associated with metritis and endometritis: fimH, hlyA, cdt, kpsMII, ibeA, and astA. The virulence factor gene fimH was the most prevalent and the most significant: intrauterine E. coli carrying fimH and at least 1 of the other 5 identified virulence factors were pathogenic, and phylogenetic analysis based on the nucleotide sequence of DNA gyrase from 41 such IUEC revealed 2 clades.
据信，大肠杆菌与产后子宫炎和子宫内膜炎有关，但它们在这两种疾病发病机制中的作用仍未确定。在这项研究中，从纽约伊萨卡附近 4 家商业农场的 374 头泌乳荷斯坦奶牛收集了用于分离大肠杆菌的子宫拭子。总共有 374 头奶牛中的 125 头（33.4%）大肠杆菌培养阳性。使用标准多重 PCR 方案筛选分离株中存在的 32 种毒力因子基因。与分娩单胎活雌性犊牛的奶牛相比，双胎分娩的奶牛子宫内大肠杆菌污染的可能性高 4.4 倍。死产和单胎活雄性犊牛的分娩也增加了大肠杆菌宫内污染的几率（分别为 3.7 倍和 1.6 倍），而活雌性犊牛的分娩则降低了这种几率。6 种毒力因子，与肠道外和肠聚集性大肠杆菌共同存在，与子宫炎和子宫内膜炎有关： fimH、hlyA、cdt、kpsMII、ibeA 和 astA。毒力因子基因 fimH 最为普遍和显著：携带 fimH 基因和至少其他 5 种鉴定出的毒力因子之一的宫内大肠杆菌具有致病性，基于 41 种此类 IUEC 的 DNA 拓扑异构酶的核苷酸序列进行的系统发育分析显示有 2 个分支。
