Relation between ISCR1 and ESBLs gene in third generation cephalosporinresistant clinical strains of Enterobacteriaceae

Abstract:

ObjectiveTo study the distribution of insertion sequence common region1(ISCR1) in local third generation cephalosporinresistant clinical strains of Enterobacteriaceae and the relationship between ISCR1 and ESBLs.MethodsAntimicrobial susceptibilities were tested by microdilution broth method;  ESBLs phenotypic confirmatory test were performed by double disk diffusion method; ISCR1 gene, SHV,TEM, and CTXMESBLs genes were amplified by PCR and analysed by singlestrand conformation polymorphism (PCRSSCP) and DNA sequencing , and the relationship between ISCR1 and ESBLs gene was detected by PCRmapping.ResultsAmong 83 strains , 17 isolates habored ISCR1 gene,6 of which were  positive  in ESBLs phenotypic confirmatory test,including 2 Escherichia coli strains（EA791,EA1367）,3 Enterobacter cloacae （EC1322,EC1342,EC553） , and 1 Klebsiella oxytoca (K386),  EA791,EC553 and K386 all contained CTXM1 ESBLs gene; EA1367 contained  both CTXM1 and CTXM9 group ESBLs gene ;EC1322 and EC1342 both contained SHV12 ESBLs gene; all  6 strains carried TEMESBL gene which were verified by PCRSSCP. PCRmapping revealed that there’s no relation between ISCR1 and ESBLs gene. ConclusionISCR1 element exist in local third generation cephalosporinresistant clinical strains of Enterobacteriaceae, the study found no evidence of direct relationship between ISCR1 and ESBLs, the element maybe play a role in horizontal transmission of other drugresistant genes.