羊腹泻大肠杆菌整合子及ESBLs携带情况检测OA北大核心

To determine the resistance mechanisms of diarrheagenic Escherichia coli in sheep in Inner Mongolia Autonomous Region,this study utilized PCR methods to detect integrase genes(types Ⅰ,Ⅱ,Ⅲ),resistance gene cassettes,and genes encoding extended-spectrum β-lactamases(ESBLs)in bacterial strains isolated from farms around Hohhot.The results showed that out of 108 diarrheagenic E.coli strains from sheep,42 strains tested positive for type Ⅰ integrase genes and resistance gene cassette insertion regions,with a detection rate of 38.9％.Type Ⅱ and Ⅲ integrase genes were not detected.Five types of gene cassettes were prevalent among the strains,mainly carrying resistance genes for trimethoprim(dfr)and aminoglycosides(aadA).The blaTEM gene was detected in 83 strains(76.9％),while blaSHV and blaCTX genes were not amplified by PCR.Plasmid DNA successfully amplified blaTEM-type ESBLs genes in 40 strains of type Ⅰ integron-positive bacteria.The results indicate a high carriage rate of type Ⅰ integrons in diarrheagenic E.coli from sheep in Inner Mongolia.The resistance of these strains to sulfonamides,trimethoprim,and aminoglycosides is closely related to the carried resistance gene cassettes.The production and dissemination of ESBLs in these isolates are mediated by their plasmids,which may be the main reason for their resistance to β-lactam antibiotics.The widespread distribution of type Ⅰ integrons in ESBL-positive strains also facilitates the dissemination of resistance genes carried by these bacteria.This study analyzes the production and transmission of antibiotic resistance in diarrheagenic E.coli from sheep to guide clinical rational drug use.