Kassé F N, Fairbrother J M, Dubuc J
OIE Reference Laboratory for Escherichia coli (EcL), Faculté de médecine vétérinaire, C.P. 5000, St-Hyacinthe, QC, J2S 7C6, Canada.
Département de sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, C.P. 5000, St-Hyacinthe, QC, J2S 7C6, Canada.
J Dairy Sci. 2016 Jun;99(6):4656-4667. doi: 10.3168/jds.2015-10094. Epub 2016 Mar 24.
The objectives of this study were to report the prevalence of Escherichia coli and Trueperella pyogenes in the uterus of postpartum dairy cows before the onset of postpartum metritis (PPM) and to quantify their association with subsequent occurrence of PPM, to quantify the association between the presence of genes encoding E. coli virulence factors (VF) and PPM, and to determine the accuracy of using early postpartum uterine bacteriology results (bacteria and VF) to identify cows at risk of PPM. A prospective cohort study was conducted on 3 commercial dairy farms. Uterine swabs were collected from 371 Holstein dairy cows (3 commercial herds) at 1 to 7d in milk and submitted to the laboratory for identification of E. coli, T. pyogenes, and E. coli VF. A total of 40 VF were tested using the radioactive probe hybridization method. Postpartum metritis was defined as the presence of a fetid watery red-brown uterine discharge, associated with fever (rectal temperature >39.5°C), and systemic signs of illness (dullness, reduced appetite, and milk production). Surveillance of PPM was done by trained farmers blinded to laboratory results and cows were followed until 21d in milk. Statistical analyses were conducted using 2×2 tables and mixed logistical regression models. Prevalences of E. coli, T. pyogenes, and PPM were 42, 34, and 15%, respectively. A total of 32 VF were found in E. coli isolates. Most prevalent VF were extraintestinal pathogenic genes such as fimH (89%), hlyE (87%), and iss (70%). Cows positive for intrauterine E. coli were 3.2 times more likely to have subsequent PPM compared with bacteriologically negative cows. Cows with VF hra1 in their uterus were 2.7 times more likely to have PPM than cows positive for E. coli and negative for hra1 and 5.9 times more likely than bacteriologically negative cows. Cows with VF kpsMTII in their uterus were 3.2 times more likely to have PPM than cows positive for E. coli and negative for kpsMTII and 6.2 times more likely than bacteriologically negative cows. Using E. coli, hra1, and kpsMTII as predictors for subsequent PPM, positive predictive values were 23, 31, and 42%, respectively, whereas the negative predictive values were 91, 80, and 78%, respectively. Overall, these results showed that E. coli and some VF were associated with PPM.
本研究的目的是报告产后奶牛在产后子宫内膜炎（PPM）发病前子宫中大肠杆菌和化脓隐秘杆菌的流行情况，并量化它们与随后发生PPM的关联，量化编码大肠杆菌毒力因子（VF）的基因的存在与PPM之间的关联，并确定使用产后早期子宫细菌学结果（细菌和VF）来识别有PPM风险奶牛的准确性。对3个商业奶牛场进行了一项前瞻性队列研究。在产奶1至7天从371头荷斯坦奶牛（3个商业牛群）采集子宫拭子，并提交至实验室以鉴定大肠杆菌、化脓隐秘杆菌和大肠杆菌VF。使用放射性探针杂交法共检测了40种VF。产后子宫内膜炎定义为存在有恶臭的水样红棕色子宫分泌物，伴有发热（直肠温度>39.5°C）和全身疾病体征（精神沉郁、食欲减退和产奶量下降）。由对实验室结果不知情的训练有素的农民对PPM进行监测，奶牛被跟踪至产奶21天。使用2×2表格和混合逻辑回归模型进行统计分析。大肠杆菌、化脓隐秘杆菌和PPM的流行率分别为42%、34%和15%。在大肠杆菌分离株中总共发现了32种VF。最常见的VF是肠道外致病基因，如fimH（89%）、hlyE（87%）和iss（70%）。子宫内大肠杆菌呈阳性的奶牛随后发生PPM的可能性是细菌学检测呈阴性奶牛的3.2倍。子宫内有VF hra1的奶牛发生PPM的可能性比大肠杆菌呈阳性但hra1呈阴性的奶牛高2.7倍，比细菌学检测呈阴性的奶牛高5.9倍。子宫内有VF kpsMTII的奶牛发生PPM的可能性比大肠杆菌呈阳性但kpsMTII呈阴性的奶牛高3.2倍，比细菌学检测呈阴性的奶牛高6.2倍。以大肠杆菌、hra1和kpsMTII作为随后发生PPM的预测指标，阳性预测值分别为23%、31%和42%，而阴性预测值分别为91%、80%和78%。总体而言，这些结果表明大肠杆菌和一些VF与PPM有关。
