Study on Florfenicol-resistant Induction in vitro and Changes of Drug Sensitivity of Swine E.coli O157:H7 |
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| Authors: | FENG Shi-wen LI Jun ZENG Yun YANG Wei CHEN Ze-xiang PAN Yan PENG Hao |
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| Institution: | 1. College of Animal Science and Technology, Guangxi University, Nanning 530005, China;2. Guangxi Veterinary Institute, Nanning 530001, China;3. Guangxi Key Laboratory of Animal Vaccines and New Technology, Nanning 530001, China |
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| Abstract: | To preliminary investigate the mechanism of drug resistance and drug-resistant elimination of swine E.coli O157:H7,sub-inhibitory concentration in vitro drug-induced method was used in this study,for inducing two strains of E.coli O157:H7 becoming florfenicol highly resistant strains,and eliminated florfenicol resistance of florfenicol-resistant strains by continuous cultured without florfenicol pressure.The drug sensitivity and resistant genes of florfenicol-induced strains and florfenicol-resistance eliminated strains were detected.The results showed that compared with original strains,after drug-resistant induction by florfenicol,swine E.coli O157:H7 were resistant to florfenicol,amoxicillin,cefazolin,cephradine and cephalothin from high sensitivity,and resistant to cefotaxime,ofloxacin,ciprofloxacin and azithromycin from moderate sensitivity.However,after florfenicol-resistance eliminated,swine E.coli O157:H7 restored sensitivity to these drugs.In addition,florfenicol resistance gene,quinolone resistance genes and β-lactamase genes were found in the plasmids of swine E.coli O157:H7,the resistance genes were consistent with the resistance phenotype.According to the results,with the long-term presence of florfenicol pressure,swine E.coli O157:H7 resistant to florfenicol,and acquired penicillins,cephalosporins and quinolones cross-resistance;While swine E.coli O157:H7 was eliminated partial drug-resistance by continuous culture without florfenicol pressure. |
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| Keywords: | swine E coli O157:H7 florfenicol drug-resistant induction drug-resistant elimination cross-resistance |
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