Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
Foodborne Pathog Dis. 2012 Nov;9(11):992-1001. doi: 10.1089/fpd.2012.1175. Epub 2012 Sep 6.
A total of 344 commensal Escherichia coli isolates from clinically healthy pigs were examined for antimicrobial resistance phenotypes, class 1 integrons, resistance genes, virulence gene profile, and phylogenetic groups. The majority of E. coli isolates were resistant to tetracycline (96.2%) and ampicillin (91.6%). Up to 98% were multidrug resistant. Seventy-three percent of the isolates carried class 1 integrons. Inserted-gene cassette arrays in variable regions included incomplete sat, aadA22, aadA1, dfrA12-aadA2, and sat-psp-aadA2, of which the aadA2 gene cassette was most prevalent (42.9%). Horizontal transfer was detected in eight E. coli isolates carrying class 1 integrons with dfrA12-aadA2 gene cassette array. Sixteen resistance genes were identified among the E. coli isolates with corresponding resistance phenotype. Ten virulence genes (including elt, estA, estB, astA, faeG, fasA, fedA, eaeA, paa, and sepA) were detected, of which fasA was most commonly found (98.3%). Most of the E. coli isolates belonged to phylogenetic group B1. Significantly positive associations were observed between some virulence genes and some resistance phenotypes and genotypes (p < 0.05). The results support a finding that commensal E. coli have a role as reservoirs for antimicrobial resistance-encoding genes and virulence determinants.
从临床健康猪中总共检测了 344 株共生大肠杆菌分离株的抗菌药物耐药表型、I 类整合子、耐药基因、毒力基因谱和进化群。大多数大肠杆菌分离株对四环素（96.2%）和氨苄西林（91.6%）具有耐药性。高达 98%的分离株为多药耐药。73%的分离株携带 I 类整合子。可变区插入基因盒阵列包括不完全 sat、aadA22、aadA1、dfrA12-aadA2 和 sat-psp-aadA2，其中 aadA2 基因盒最为常见（42.9%）。在携带 dfrA12-aadA2 基因盒阵列的 8 株携带 I 类整合子的大肠杆菌分离株中检测到水平转移。在具有相应耐药表型的大肠杆菌分离株中鉴定出 16 个耐药基因。检测到 10 个毒力基因（包括 elt、estA、estB、astA、faeG、fasA、fedA、eaeA、paa 和 sepA），其中 fasA 最为常见（98.3%）。大多数大肠杆菌分离株属于进化群 B1。一些毒力基因与一些耐药表型和基因型之间存在显著的正相关关系（p<0.05）。结果支持这样一种发现，即共生大肠杆菌作为携带抗菌药物耐药编码基因和毒力决定因素的储库发挥作用。
