Morabito S, Dell'Omo G, Agrimi U, Schmidt H, Karch H, Cheasty T, Caprioli A
Laboratorio di Medicina Veterinaria, Istituto Superiore di Sanità, Viale Regina Elena 299, I-00161 Rome, Italy.
Vet Microbiol. 2001 Sep 28;82(3):275-83. doi: 10.1016/s0378-1135(01)00393-5.
Escherichia coli strains producing a variant of Shiga toxin 2 (Stx2), designated Stx2f, have been recently described in the stools of feral pigeons. During 1997-1998, 649 pigeons were trapped and examined in three different squares of Rome. Stool samples were collected from each bird and enrichment cultures were examined for the presence of Stx by the vero cell assay. Stx-producing E. coli (STEC) were isolated from the positive cultures and characterized by serotyping and PCR analysis of stx and other virulence-related genes. Stx was detected in 10.8% of the stool enrichment cultures. The percentage of positive birds did not differ significantly for the three flocks considered and the season of sample collection. Conversely, STEC carriage was significantly more frequent in young than in adult birds (17.9 versus 8.2%). None of the birds examined showed signs of disease. STEC strains were isolated from 30 of 42 Stx-positive cultures examined. All the strains produced Stx2f, and most of them possessed genes encoding for intimin and the cytolethal distending toxin (CLDT). Six serogroups were identified, but most of the isolates belonged to O45, O18ab, and O75. Molecular typing indicated that most of the isolates within a flock were clonally-related. This work confirms that pigeons represent a natural reservoir of STEC strains characterized by the production of the toxin variant Stx2f, and by the frequent presence of eae and cldt genes. Further work is needed to clarify whether these STEC may represent a cause of avian disease or even a potential health hazard for humans.
最近在野生家鸽粪便中发现了能产生志贺毒素2（Stx2）变体（称为Stx2f）的大肠杆菌菌株。1997年至1998年期间，在罗马的三个不同广场捕获并检查了649只家鸽。从每只鸽子采集粪便样本，通过Vero细胞试验检测富集培养物中是否存在Stx。从阳性培养物中分离出产志贺毒素大肠杆菌（STEC），并通过血清分型以及对stx和其他毒力相关基因进行PCR分析来进行鉴定。在10.8%的粪便富集培养物中检测到了Stx。所考虑的三个鸽群以及样本采集季节中，阳性鸽子的百分比没有显著差异。相反，STEC携带在幼鸽中比成年鸽更常见（17.9%对8.2%）。所有检查的鸽子均未表现出疾病迹象。在所检查的42份Stx阳性培养物中，从30份中分离出了STEC菌株。所有菌株均产生Stx2f，并且大多数菌株拥有编码intimin和细胞致死膨胀毒素（CLDT）的基因。鉴定出了六个血清群，但大多数分离株属于O45、O18ab和O75。分子分型表明，一个鸽群中的大多数分离株在克隆上相关。这项工作证实，家鸽是STEC菌株的天然宿主，这些菌株的特征是产生毒素变体Stx2f，并且经常存在eae和cldt基因。需要进一步开展工作，以阐明这些STEC是否可能是禽类疾病的病因，甚至对人类构成潜在的健康危害。
