Prada J, Baljer G, De Rycke J, Steinrück H, Zimmermann S, Stephan R, Beutin L
Robert Koch-Institut des Bundesgesundheitsamtes, Berlin, Germany.
Vet Microbiol. 1991 Sep;29(1):59-73. doi: 10.1016/0378-1135(91)90110-2.
Twenty-four hemolysin producing (Hly+) strains of Escherichia coli isolated from dogs with gastroenteritis were investigated for their virulence markers and their phenotypic properties. The strains were distributed over eleven known E. coli O-serogroups and most of them were heterogeneous for their phenotypes. All strains were found to produce alpha-hemolysin which was detected by Southern hybridization and colony immunoblotting using a specific gene probe and a monoclonal antibody. Eight strains were carrying plasmids encoding alpha-hemolysin sequences (hly-plasmids) and 16 strains carried chromosomal hly-determinants. Twelve of the strains showed enterotoxic activities which were tested for in different assays. Among these, three O42:H37 and two O70:H-strains carrying hly-plasmids were found to harbour other plasmids encoding the heat-stable enterotoxin STA1. The other seven strains showing enterotoxicity in the ileal loop or the suckling mouse assay were negative for STA1, STA2, or LT. None of the 24 strains were positive for invasiveness or for production of Vero (Shiga-like) toxins. The production of alpha-hemolysin was closely associated with the production of cytotoxic necrotizing factor (CNF), which was detected in 17 of 24 strains. Of these, 16 elaborated CNF1 and one strain produced an unknown CNF type. Surprisingly, all strains carrying ST-plasmids and six of eight strains carrying hly-plasmids were negative for CNF. Thus, in canine E. coli strains CNF production seems to be closely associated with production of chromosomally encoded alpha-hemolysin whereas hly-plasmids are more often associated with ST-producing, CNF negative isolates.
对从患肠胃炎的犬只中分离出的24株产溶血素（Hly+）大肠杆菌菌株进行了毒力标记和表型特性研究。这些菌株分布在11个已知的大肠杆菌O血清群中，大多数菌株的表型具有异质性。所有菌株均被发现产生α-溶血素，通过Southern杂交和使用特异性基因探针及单克隆抗体的菌落免疫印迹法检测到。8株菌株携带编码α-溶血素序列的质粒（hly-质粒），16株菌株携带染色体hly决定簇。12株菌株表现出肠毒素活性，并在不同检测中进行了测试。其中，3株O42:H37和2株携带hly-质粒的O70:H菌株被发现含有其他编码热稳定肠毒素STA1的质粒。在回肠环或乳鼠试验中表现出肠毒素活性的其他7株菌株对STA1、STA2或LT呈阴性。24株菌株中无一株具有侵袭性或产生Vero（志贺样）毒素呈阳性。α-溶血素的产生与细胞毒性坏死因子（CNF）的产生密切相关，在24株菌株中有17株检测到CNF。其中，16株产生CNF1，1株产生未知类型的CNF。令人惊讶的是，所有携带ST-质粒的菌株和8株携带hly-质粒的菌株中的6株对CNF呈阴性。因此，在犬大肠杆菌菌株中，CNF的产生似乎与染色体编码的α-溶血素的产生密切相关，而hly-质粒更常与产ST、CNF阴性的分离株相关。
