Resumo

Fluoroquinolones are a group of synthetic antimicrobials with broad spectrum of clinical use. In the last years, the reports of fluoroquinolone-resistant isolates are increasing due to extensive use of these antimicrobials. The rapid spread of the plasmid-located fluoroquinolone-resistance genes, especially the qnr gene, is worrisome, mainly in community-acquired infections. The aim of this study was to investigate the presence of the qnr genes, as well as to perform the molecular and microbiological characterization of the ciprofloxacin-resistant enterobacteriaceae isolates collected during a three month period (Oct 2012 to Jan 2013), identified by conventional biochemical methods. The minimal inhibitory concentrations (MIC) were determined using microdilution broth method. qnrA, qnrB, qnrS, blaCTX-M and blaTEM genes and class 1 elements were investigated by PCR. Sixty-one ciprofloxacin-resistant enterobacteriaceae isolates (Klebsiella spp. [6], Escherichia coli [52], Serratia marcescens [1], Enterobacter cloacae [1] e Providencia stuartii [1]) were identified from distinct samples and origins. Only two Klebsiella pneumoniae isolates (A-04 – nosocomial infection and KP-02 - community-acquired infection) presented the qnr gene, identified both as qnrB19. These isolates presented MIC for ciprofloxacin and nalidixic acid of ≥ 8μg/mL and > 128μg/mL, respectively. Only the A-04 isolate showed the blaCTX-M-2 and blaTEM genes and a class 1 integron carrying aac(6’)-Iq e aadA1 genes, that confer aminoglicosides resistance. Despite the absence of other resistance genes in KP-02, the detection of qnrB19 draws attention to the spread of this resistance mechanism in community isolates. This is the first report of qnrB19 in northeastern Brazil and in community-acquired infection. Financial support: CAPES, CNPq and FACEPE.