Methods: Antimicrobial susceptibility testing of 17 antibiotics were performed. b-lactamase genes were detected. Efflux pump phenotype test and outer membrane porin SDS-PAGE were performed. Clonal relationship was investigated by PFGE (pulsed field gel electrophoresis). S1 nuclease-PFGE, Restriction Fragment Length Polymorphism(RFLP) analysis and plasmid incompatibility groups analysis were performed to analyze blaKPC-2 carrying plasmids. Epidemiological data were collected via history review.
Results: Only tigecycline and colistin maintained high level susceptibility to 14 CREA isolates. Five distinct groups (PFGE types A–E) were observed. All 14 isolates carried the blaKPC-2. Only one isolates lost Omp36 porin. Efflux pump had no contribution to these 14 isolates. S1 nuclease-PFGE indicated that the size of blaKPC-2 carrying plasmids were among 20kb to 200kb. RFLP analysis divided blaKPC-2 carrying plasmids into 7 groups. Plasmids can be divided into 5 incompatibility groups. Epidemiological and molecular investigations showed that PFGE type A group, including 11 KPC-2-producing clinical isolates, was primarily responsible for the dissemination.
Conclusion: Our findings suggest further studies should focus on judicious use of available antibiotics and strict implementation of infection-control measures to avoid the rapid spread or clonal dissemination caused by CREA in healthcare facilities