Zhu C, Harel J, Jacques M, Desautels C, Donnenberg M S, Beaudry M, Fairbrother J M
Groupe de Recherche sur les Maladies Infectieuses du Porc, Université de Montréal, Faculté de Médecine Vétérinaire, Saint-Hyacinthe, Québec, Canada.
Infect Immun. 1994 Oct;62(10):4153-9. doi: 10.1128/iai.62.10.4153-4159.1994.
Escherichia coli O45 isolates associated with swine postweaning diarrhea in Québec were characterized with respect to virulence determinants genetically and investigated for their attaching and effacing (A/E) activities by experimental inoculation of gnotobiotic piglets and by the HEp-2 cell adherence assay. All of 32 isolates tested were negative for enterotoxigenic and verotoxigenic E. coli virulence determinants, heat-labile enterotoxin (LT), heat-stable enterotoxins (STap, STb), verotoxins (VT1, VT2), and F4 (K88), F5 (K99), F6 (987P), and F41, except one STb-positive and two F4-positive isolates. A total of 25 isolates hybridized with an EaeA probe, and 11 hybridized with an enteropathogenic E. coli adherence factor (EAF) probe. None of 32 isolates hybridized with a bundle-forming pilus (BFP) probe. The EAF, EaeA, and BFP factors have been associated with human enteropathogenic E. coli strains. A total of 10 of 12 eaeA-positive porcine O45 isolates induced A/E lesions characterized by intimate adherence of bacteria to the intestinal epithelial cell membrane with effacement of the microvilli, similar to those of human attaching-effacing E. coli. However, A/E lesions were not observed in the piglets inoculated with any one of three eaeA-negative O45 isolates. All E. coli O45 isolates were non-adherent to HEp-2 cells. Thus, we have demonstrated the production of typical A/E lesions by nonenterotoxigenic E. coli O45 isolates from swine postweaning diarrhea. The results indicate the significance of the eaeA gene in A/E activities of these isolates and suggest that EAF and BFP are not involved in O45 E. coli infection of weaning piglets.
对魁北克省与猪断奶后腹泻相关的大肠杆菌O45分离株进行了毒力决定因素的基因特征分析，并通过对无菌仔猪进行实验接种以及采用HEp-2细胞黏附试验，研究了它们的黏附与脱落（A/E）活性。在检测的32株分离株中，除1株STb阳性和2株F4阳性分离株外，所有分离株的产肠毒素性大肠杆菌和产志贺毒素性大肠杆菌毒力决定因素、不耐热肠毒素（LT）、耐热肠毒素（STap、STb）、志贺毒素（VT1、VT2）以及F4（K88）、F5（K99）、F6（987P）和F41均为阴性。共有25株分离株与EaeA探针杂交，11株与肠致病性大肠杆菌黏附因子（EAF）探针杂交。32株分离株中无一株与束状菌毛（BFP）探针杂交。EAF、EaeA和BFP因子与人类肠致病性大肠杆菌菌株有关。12株eaeA阳性的猪O45分离株中有10株诱导产生了A/E损伤，其特征为细菌紧密黏附于肠上皮细胞膜并伴有微绒毛脱落，类似于人类黏附-脱落性大肠杆菌。然而，在接种了3株eaeA阴性的O45分离株中任何一株的仔猪中均未观察到A/E损伤。所有大肠杆菌O45分离株均不黏附于HEp-2细胞。因此，我们证明了来自猪断奶后腹泻的非产肠毒素性大肠杆菌O45分离株可产生典型的A/E损伤。结果表明eaeA基因在这些分离株的A/E活性中具有重要意义，并提示EAF和BFP不参与断奶仔猪的O45大肠杆菌感染。
