ISEcp1 element in association with bla(CTX-M) genes of E. coli that produce extended-spectrum β-lactamase among the elderly in community settings.

INTRODUCTION: This study analyzed the relationship between the ISEcp1 element and bla(CTX-M) genes of Escherichia coli isolates that produce extended-spectrum β-lactamase (ESBL) in community settings.

METHODS: Nineteen E. coli isolates that produced CTX-M-type β-lactamase were collected from four communities of elderly people in Shenyang, China. Polymerase chain reaction (PCR) amplification and direct sequencing were used to detect the insertion of the ISEcp1 element into the genetic environment of the bla(CTX-M) genes.

RESULTS: The ISEcp1 element was associated with several bla(CTX-M) gene types, including CTX-M-14, CTX-M-24, CTX-M-22, and CTX-M-79. Sequence analysis revealed that all of the ISEcp1-like DNA sequences contained the putative promoter region that is involved in CTX-M genes transcription. ISEcp1 insertion sequences were observed 42-127bp upstream of the open reading frames (ORFs) that encode the CTX-M enzymes in all 15 strains. The CTX-M-79 β-lactamase-encoding gene was observed with a different ISEcp1 insertion site and variable sequences between the ISEcp1 and bla(CTX-M-79) gene. For one strain (T298), the ISEcp1 element was disrupted by IS10.

CONCLUSION: This work confirmed that the ISEcp1 elements were closely linked to bla(CTX-M) genes in community isolates from Shenyang, China.