Detection and analysis of plasmid-mediated carbapenem-hydrolyzing enzyme KPC-2 in carbapenem-resistant Escherichia coli / 中华检验医学杂志

ABSTRACT

Objective To study molecular epidemiology and carbapenem-resistance mechanism of four Escherichia coli strains isolated from general surgery wards. Methods Antibiotic susceptibility was carried out by K-B gar diffusion and agar dilution methods. Carbapenemases were screened by three dimensional test and EDTA-Na_2-disk synergy test. Pulsed-field gel electropboresis (PFGE) was performed to analyze molecular epidemiology of isolates. Plasmid was extracted by using an alkalinelysis technique. Conjunction experiment, transformation assay, specific PCR and DNA sequencing were performed to confirm carbapenemase genotype and its transmission mechanism Results Four Escherichia coli isolates were resistant to most antimicrobials including carbapenem. PFGE showed that the four isolates belong to four different clonal strains. Specific PCR and DNA sequence analysis identified that carbapenem resistance in four clinical isolates was mediated by KPC-2 encoded on an approximately 56 000 bp plasmid, and this plasmid did not harbor aminoglycosides and fluorquinolones resistant genes. Conclusion Four Escherichia coli isolates with carbapenem resistance are obtained from our hospital, and KPC-2 plasmid is main cause of carbapenem resistance in these isolates.