Detection and analysis of drug resistance genes in 2 carbapenem resistant Raoultella planticola isolates

OBJECTIVE To investigate the drug resistance genes carried on carbapenem resistant Raoultella planticola isolates.METHODS Two carbapenem resistant R.planticola strains were collected from sputum samples in October 2014 and March 2015. Isolates were identified by Vitek2-compact and confirmed with 16S rRNA method, and the susceptibility of antimicrobial agents was measured by E-test. The genes were amplified by PCR, including carbapenemase (KPC,GES,NDM-1,IMI,IMP,VIM,SIM,OXA-48), extended spectrum beta-lactamases(TEM,SHV,CTX-M,VEB,PER), plasmid-mediated quinolone resistance (PMQR) genes(qnrA, qnrB, qnrS, and aac(6')-Ib-cr), class I integron structure, and plasmids were analyzed using southern hybridization.RESULTS The strain 1 showed the coexistence of blaKPC-2 and qnrB4 genes. Analysis of the class 1 integron structure showed that the gene cassettes contained resistant determinants as arr-3-dfrA27.The isolate 2 also was positive for the blaIMP-4, blaTEM-1, blaCTX-M-3, blaSHV-12, qnrS1 and aac(6')-Ib-cr, and the strain only included the empty integron structure. Plasmid analysis and southern bridization revealed that the blaKPC-2 and blaIMP-4 genes were located on transferable plasmid (54-60 kb).CONCLUSION Two carbapenemase-producing R.planticola strains carried KPC-2 and IMP-4 gene, respectively. Therefore, a routine drug resistance surveillance initiative should be established for continued monitoring and enhanced efforts to control these resistant bacteria dissemination.