Best Angus, La Ragione Roberto M, Clifford Derek, Cooley William A, Sayers A Robin, Woodward Martin J
Department of Food and Environmental Safety, Veterinary Laboratories Agency (Weybridge), Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK.
Vet Microbiol. 2006 Mar 10;113(1-2):63-72. doi: 10.1016/j.vetmic.2005.10.033. Epub 2005 Dec 7.
Isolation of Shiga-toxin (Stx) positive Escherichia coli O157:H7 from commercially grown pigs has been reported. Furthermore, experimental infection studies have demonstrated that Stx-positive E. coli O157:H7 can persist in 12-week-old experimentally orally inoculated conventional pigs for up to 2 months and that persistence was not dependent upon intimin. We have shown that the flagellum of Stx-negative E. coli O157:H7 does not have a role to play in pathogenesis in ruminant models whereas, in poultry, the flagellum of E. coli O157:H7 was important for long-term persistent infection. The contribution of the flagellum of Stx-negative E. coli O157 in the colonisation of pigs was investigated by adherence assays on a porcine (IPI-21) cell line, porcine in vitro organ culture (IVOC) and experimental oral inoculation of conventional 14-week-old pigs. E. coli O157:H7 NCTC12900nal(r) and isogenic aflagellate and intimin deficient mutants adhered equally well to IPI-21 cells. In porcine IVOC association assays, E. coli O157:H7 NCTC12900nal(r) was associated in significantly higher numbers to tissues from the caecum and the terminal rectum than other sites. The aflagellate and intimin deficient mutants significantly adhered in greater numbers to more IVOC gastrointestinal tissues than the parent. Groups of 14-week-old pigs were dosed orally with 10(10)CFU/10ml of either E. coli O157:H7 NCTC12900nal(r) or isogenic aflagellate and intimin deficient mutants and recovery of each test strain was similar. Histological analysis of pig tissues at post mortem examination revealed that E. coli O157 specifically stained bacteria were associated with the mucosa of the ascending and spiral colon. These data suggest that colonisation and persistence of Stx-negative E. coli O157:H7 in pigs, involves mechanisms that do not require the flagellum or intimin.
已有报道称从商业化养殖的猪中分离出了产志贺毒素（Stx）的大肠杆菌O157:H7。此外，实验感染研究表明，产Stx的大肠杆菌O157:H7在12周龄经实验性口服接种的传统猪中可存活长达2个月，且这种存活不依赖于紧密素。我们已经表明，产Stx阴性的大肠杆菌O157:H7的鞭毛在反刍动物模型的发病机制中不起作用，而在禽类中，大肠杆菌O157:H7的鞭毛对于长期持续感染很重要。通过在猪（IPI-21）细胞系上进行黏附试验、猪体外器官培养（IVOC）以及对14周龄传统猪进行实验性口服接种，研究了产Stx阴性的大肠杆菌O157的鞭毛在猪定殖中的作用。大肠杆菌O157:H7 NCTC12900nal(r)及其同基因无鞭毛和紧密素缺陷突变体对IPI-21细胞的黏附能力相同。在猪IVOC关联试验中，大肠杆菌O157:H7 NCTC12900nal(r)与盲肠和直肠末端组织的关联数量显著高于其他部位。无鞭毛和紧密素缺陷突变体比亲本在更多的IVOC胃肠道组织中显著黏附更多。给14周龄的猪口服10(10)CFU/10ml的大肠杆菌O157:H7 NCTC12900nal(r)或同基因无鞭毛和紧密素缺陷突变体，每种测试菌株的回收率相似。死后对猪组织的组织学分析表明，大肠杆菌O157特异性染色的细菌与升结肠和螺旋结肠的黏膜相关。这些数据表明，产Stx阴性的大肠杆菌O157:H7在猪中的定殖和持续存在涉及不需要鞭毛或紧密素的机制。
