Molecular Epidemiological Analysis of Avian Extended Spectrum p-lactamases Producing Escherichia coli in Shandong Province
[Objective]The experiment aims to analyze the drug resistance,the drug resistance mechanism,multilocus sequence typing(MLST),the virulence genes,the affinity and Inc-type plasmids of extended-spectrum β-lactamases(ESBLs)producing Escherichia coli of avian origin in Shandong province,so as to provide reference for the rational use of antibiotics in avian clinical prevention and treatment of such bacterial diseases.[Method]38 strains of ESBLs producing E.coli,isolated from avian farms in Shandong during April 2021 to July 2021,were recovered.The antimicrobial susceptibility test of these isolates against 16 kinds of antimicrobials was determined by the broth microdilution method.The drug resistance,the virulence genes,MLST and Inc-type plasmids were detected by whole genome sequencing.Parsnp was used to analyze the phylogenetic relationship among these isolates.[Result]The antimicrobial susceptibility test revealed that all strains were resistant to ampicillin,ceftiofur and ceftazidime.The resistance to sulfisoxazole(97.4％),trimethoprim/sulfamethoxazole(94.7％),tetracycline(89.5％),florfenicol(86.8％),spectinomycin(84.2％)was serious.Analysis results of whole genome sequencing showed that 34.2％of 38 strains of ESBLs producing E.coli carried blaCTX-M-55 in blaCTX-M type,22.1％carried blaNDM-5 and 10.5％carried blaNDM-4 in blaNDM type.ESBLs producing E.coli isolates carried a large number of resistance genes that mediate commonly used antimicrobials in clinical practice,and adhesion,invasion,serum resistance,iron transport virulence genes.MLST results revealed that ST10(13.2％)was the most prevalent ST among ESBLs producing E.coli isolates,followed by ST616(10.5％)and ST746(10.5％).Phylogenetic tree analysis showed that ST10,ST616 and ST746 had the same origin,respectively.Inc-type plasmids results revealed that the carrier rate of IncFIB(AP001918)was the highest(68.4％),followed by IncHI2(42.1％).[Conclusion]The situation of ESBLs producing E.coli isolates remains very serious,blaCTX-M mainly accounted for the resistance to extended-spectrum β-lactams antimicrobials.Moreover,this type of strain carried a large number of virulence genes,and it was urgent to strengthen monitoring.
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