Nguyen Tan Duc, Vo Thin Thanh, Vu-Khac Hung
Department of Parasitology, Central Vietnam Veterinary Institute, km4 Dong De Street, Nha Trang, Vietnam.
J Vet Sci. 2011 Jun;12(2):159-64. doi: 10.4142/jvs.2011.12.2.159.
This study was conducted to determine the prevalence and characteristics of pathogenic Escherichia (E.) coli strains from diarrheic calves in Vietnam. A total of 345 E. coli isolates obtained from 322 diarrheic calves were subjected to PCR and multiplex PCR for detection of the f5, f41, f17, eae, sta, lt, stx1, and stx2 genes. Of the 345 isolates, 108 (31.3%) carried at least one fimbrial gene. Of these 108 isolates, 50 carried genes for Shiga toxin and one possessed genes for both enterotoxin and Shiga toxin. The eae gene was found in 34 isolates (9.8%), 23 of which also carried stx genes. The Shiga toxin genes were detected in 177 isolates (51.3%) and the number of strains that carried stx1, stx2 and stx1/stx2 were 46, 73 and 58, respectively. Among 177 Shiga toxin-producing E. coli isolates, 89 carried the ehxA gene and 87 possessed the saa gene. Further characterization of the stx subtypes showed that among 104 stx1-positive isolates, 58 were the stx1c variant and 46 were the stx1 variant. Of the 131 stx2-positive strains, 48 were stx2, 48 were stx2c, 11 were stx2d, 17 were stx2g, and seven were stx2c/stx2g subtypes. The serogroups most prevalent among the 345 isolates were O15, O20, O103 and O157.
本研究旨在确定越南腹泻犊牛中致病性大肠杆菌菌株的流行情况和特征。从322头腹泻犊牛中获得的345株大肠杆菌分离株进行了PCR和多重PCR检测，以检测f5、f41、f17、eae、sta、lt、stx1和stx2基因。在345株分离株中，108株（31.3%）携带至少一种菌毛基因。在这108株分离株中，50株携带志贺毒素基因，1株同时携带肠毒素和志贺毒素基因。34株（9.8%）分离株中发现了eae基因，其中23株还携带stx基因。177株（51.3%）分离株中检测到志贺毒素基因，携带stx1、stx2和stx1/stx2的菌株数量分别为46、73和58株。在177株产志贺毒素大肠杆菌分离株中，89株携带ehxA基因，87株携带saa基因。stx亚型的进一步特征表明，在104株stx1阳性分离株中，58株为stx1c变体，46株为stx1变体。在131株stx2阳性菌株中，48株为stx2，48株为stx2c，11株为stx2d，17株为stx2g，7株为stx2c/stx2g亚型。345株分离株中最常见的血清型为O15、O20、O103和O157。
