Screening and structural analysis of integrase genes in gram-negative bacteria

Objective To investigate class 1,2 and 3 integron-associated integrase genes in gram negative bacteria,and analyze the structure of class 1 integron.MethodsPCR,T-A clone and sequencing were used to amplify and analyze integrase genes and the structure of class 1 integron.ResultsThe prevalence of class I integrase gene was 43.2%,including 61.0% in E.coli,14.3% in K.pneumoniae,37.3% in A.baumannii,and 20% in E.cloacae.The prevalence of integrase genes encoding class Ⅱ and Ⅲ integrase was very low.We identified 5 resistant gene cassettes:dfr17,aadA5,aadA1,aadA2,dhⅪ,and found 4 gene-cassette arrays.ConclusionsThe prevalence of class I integron is high in gram-negative isolates in Zhenjiang area.