Drug resistance and transmission characteristics of animals-derived polymyxin-re-sistant Escherichia coli carrying blaCTX-M in Xinjiang
To investigate the epidemiological characteristics of polymyxin-resistant animals-derived Escherichia coli carrying blaCTX-M in Xinjiang,40 isolates of blaCTX-M-producing and polymyxin-re-sistant E.coli of pig,sheep,camel,horse,chicken,goose,pigeon,dog and cat were screened for re-sistance phenotypes using the Kirby-Bauer method,and resistance genes,integron detection and plasmid replicon typing were performed by PCR,and the horizontal transfer of polymyxin-resistant phenotypes was investigated by conjugation transfer test.The results showed that the resistance rates of these E.coli to ampicillin,amoxicillin,cotrimoxazole,ceftriaxone,tetracycline,streptomy-cin,cefotaxime and gentamicin were 82.5％-100％;to flupenthixol,fosfomycin,ciprofloxacin,levofloxacin,ceftazidime,azithromycin,amikacin and cefepime were 20.0％-67.5％;to piperacil-lin/tazobactam,ampicillin/sulbactam,cefoxitin and imipenem were 2.5％-10.0％,all of which were multi-drug resistant.Detection of resistance genes in 40 test isolates mcr-1,12.5％;blaCTX-M-1,85％;bla CTX-M-9,15％;blaTEM,60％;floR,70％;tetA,55％;tetG,17.5％;sul2,37.5％;sul1,17.5％;aad A1,35％;strA,32.5％;aac,17.5％.mcr2-10,bla CTX-M-2,blaSHV,strB and tetE were not detec-ted.Four plasmid replicon types were detected,IncFIB,52.5％;IncHI2,20％;IncN,20％;IncFIA,7.5％.Nine isolates carried class Ⅰ integrons and no class Ⅱ integrons were detected.Forty isolates were able to transfer polymyxin B resistance phenotypes horizontally,but no resistance genes,plasmids and integrons were detected in transconjugants.It was concluded that animals-derived E.coli carrying bla CTX-M and polymyxin resistant in Xinjiang are in a serious situation of multi-drug resistance and various types of resistance genes carried,all of which can transfer the polymyxin B resistance phenotype horizontally,and polymyxin should be used cautiously in order to slow down the development of drug-resistant bacteria.
Escherichia coli carrying bla CTX-Mpolymyxin resistanceepidemiological characteristicsanimalXinjiang
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