Occurrence of qnrB1 and qnrB12 genes, mutation in gyrA and ramR, and expression of efflux pumps in isolates of Klebsiella pneumoniae carriers of blaKPC-2.

PURPOSE: The occurrence of quinolone-resistance genes (qnrA, qnrB and qnrS), the presence of mutations in gyrA, gyrB and parC, as well as the expression of efflux pumps (acrB and acrF) and mutations in the gene ramR.

METHODOLOGY: Were investigated in 30 blaKPC-2-positive isolates of Klebsiella pneumoniae taken from infection and colonization in hospital patients from Recife-PE, Brazil. The detection of the qnr, acrB and acrF genes and analysis of the mutations in ramR and the quinolone-resistance-determining regions of gyrA, gyrB and parC were performed by PCR followed by DNA sequencing.

RESULTS

Among the isolates analysed, 73.3 % (n=22) presented the qnrB gene. For the DNA sequencing, six isolates (K3-A2, K12-A2, K25-A2, K27-A2, K19-A2 and K3-C2) were selected and the qnrB1 and qnrB12 variants were detected. This is the first ever report, to the best of our knowledge, of the presence of qnrB12 in K. pneumoniae. This is also the first report, to the best of our knowledge, of the presence of qnrB1 or qnrB12 with blaKPC-2 in K. pneumoniae in Brazil. Mutations were observed in gyrA S83 and in ramR. All isolates presented genes for the acrB and acrF efflux pumps and the reverse transcription PCR performed showed that the pumps were being expressed.

CONCLUSION

KPC-2-positive isolates colonizing patients, which also showed qnrB, mutation in gyrA and efflux pumps, may be important reservoirs for disseminating these resistance mechanisms in the hospital environment.