Analysis Of Drug Resistance Genes And Mobile Genetic Elements In Drug-resistant Escherichia Coli

Objective:To explore the Escherichia coli on the distribution of β-lactams resistance genes,aminoglycosides resistance genes and the mobile genetic elements.Analysis the genetic relationship between these strains,and provide the basis for guiding the clinical use of antibiotics.Methods:1.20 identified Escherichia coli isolates were collected from hospitalized patients in wuxi people’s hospital,and drug sensitive test were performed.2.Polymerase chain reaction(PCR)was used to detect the 21 β-lactamase genes,7kinds of aminoglycoside resistance genes,and 8 mobile genetic elements marker gene.Take these genes as molecular markers for cluster analysis.Results:1.All the 20 strains of Escherichia coli were resistant to all the 9 antibiotics used in the automatic drug susceptibility testing,but they were all sensitive to imipenem and meropenem,so all of them are drug-resistant Escherichia coli;2.The results of β-lactamase resistance genes detection: No β-lactamase genes were found in 2 of these strains.5 kinds of β-lactamase genes were found in the rest18strains: TEM、CTX-M-1、CTX-M-9、LAT/CYM、OXA-1,the positive rates being70%、30%、10%、5%、20% respectively.4 kinds of β-lactamase genes were detected coexisting in one strain.3.The results of aminoglycoside resistance gene detection: 6 aminoglycoside modifying enzyme gene were found in 20 strains:aac(3)-Ⅰ、aac(3)-Ⅱ、aac(6’)-Ⅰb、ant(3’’)-Ⅰ、aad A5、aph3’-Ⅰ,and the positive rates were 25%、35%、20%、15%、30%、15%.16 Sr RNA methyltransferase gene rmt B were not detected.At least one aminoglycoside resistant gene was detected in all the 20 strains of Escherichia coli,and 8 strains carried at least 2 aminoglycoside resistant genes concurrently;4.The results of Mobile genetic elements related to genetic marker gene detection:The positive rate of conjugative plasmid genetic marker genes tra A and tra B were both 70%.The positive rate of transposon genetic marker gene tnp513 was75% while tnp U was not found.The positive rates of Insertion sequence marker gene IS26,IS903 ISEcp1 were 95%、55% and 40% respectively.The positive rate of integron genetic marker gene int 1 was 100%.5.The results of sample clustering analysis: 20 Escherichia coli strains were divided into A,B two clusters.No.12 and No.13 in A cluster were the same clone.Conclusions:1.All the 20 Escherichia coli strains carried one or more of β-lactamase resistance genes or aminoglycoside modifying enzyme gene,which were closely related to the resistance of above drugs;2.All the 20 Escherichia coli strains carried multiple mobile genetic elements,which speed up clinical drug resistance and spread phenomenon;3.The results of sample clustering analysis indicated that clonal transmission of nosocomial infections existed.