Wang Lei, Liu Bin, Kong Qingke, Steinrück Hartmut, Krause Gladys, Beutin Lothar, Feng Lu
TEDA School of Biological Sciences and Biotechnology, Nankai University, 23# HongDa Street, TEDA, Tianjin 300457, PR China.
Vet Microbiol. 2005 Dec 20;111(3-4):181-90. doi: 10.1016/j.vetmic.2005.10.006. Epub 2005 Nov 8.
Escherichia coli strains belonging to O-serogroup 138 and 139 are important as disease agents in pigs causing post-weaning diarrhea and edema disease. Several types of shiga toxin-producing O 138 and O 139 strains were isolated from diarrheic humans and from cattle and food of bovine origin. Serotyping is the current method for detection of O 138 and O 139 strains but its applicability can be limited due to the presence of capsules and capsular-like bacterial surface antigens and in the case of rough LPS. To overcome these difficulties for diagnosis, we have developed a specific PCR method suitable for detection of different types of O 138 and O 139 strains. The O-antigen gene clusters of E. coli O 138 and O 139 type strains were sequenced, and the genes were identified on the basis of homology. By screening against 186 E. coli and Shigella type strains, two genes specific to each of E. coli O 138 and O 139 were identified, respectively, and were tested on 15 clinical and environmental isolates of those two serogroups in a double-blind test. The sensitivity of the PCR assays was determined, and the detection limits were 2 pg per mul of chromosomal DNA and 2 CFU per 10 g of water or pork samples. PCR-based detection of O-antigen specific genes of E. coli O 138 and O 139 was shown to be accurate, highly sensitive and rapid, and is suggested as a new diagnostic tool for investigations of infections and outbreaks with these strains in animals and humans and for control of food.
属于O血清群138和139的大肠杆菌菌株是引起仔猪断奶后腹泻和水肿病的重要病原体。从腹泻患者以及牛和牛源性食品中分离出了几种产志贺毒素的O 138和O 139菌株。血清分型是目前检测O 138和O 139菌株的方法，但其适用性可能因存在荚膜和类荚膜细菌表面抗原以及粗糙脂多糖的情况而受到限制。为了克服这些诊断困难，我们开发了一种适用于检测不同类型O 138和O 139菌株的特异性PCR方法。对大肠杆菌O 138和O 139型菌株的O抗原基因簇进行了测序，并根据同源性鉴定了这些基因。通过对186株大肠杆菌和志贺氏菌型菌株进行筛选，分别鉴定出了大肠杆菌O 138和O 139各自的两个特异性基因，并在双盲试验中对这两个血清群的15株临床和环境分离株进行了检测。确定了PCR检测的灵敏度，检测限为每微升染色体DNA 2皮克，每10克水或猪肉样品2个菌落形成单位。基于PCR检测大肠杆菌O 138和O 139的O抗原特异性基因被证明是准确、高度灵敏和快速的，并被建议作为一种新的诊断工具，用于调查动物和人类中这些菌株的感染和疫情以及食品控制。
