Plasmid mediated Quinolone Efflux Pumps in Escherichia coli Resistant to Third Generation Cephalosporins (TGC) in Cochabamba, Bolivia.

SABA MARIELA; RINCÓN GIOVANNA; VILLARROEL M.; AGUILAR V.; PIMENTEL T.; ALVAREZ L.; BALDERRAMA N.; GUTKIND GABRIEL; RADICE MARCELA; DI CONZA JOSÉ

Washington

Conferencia; 54th ICAAC - Annual Interscience Conference on Antimicrobial Agents and Chemotherapy; 2014

American Society of Microbiology

Background Resistance to TGC and quinolone among Enterobacteria is known to be epidemiologically related. Diverse quinolone resistance mechanisms were found in many countries being plasmid mediated-quinolone resistance (PMQR) of great concern. PMQR determinants include: qnr, aac(6?)-Ib-cr and efflux pumps qepA and oqxAB. This mechanism gives a low resistance to quinolones, but to a certain antibiotic concentration, could keep resistant and could be the source of mutations in the chromosome and award high resistance. These efflux pumps were mainly described in isolates from farm and poultry but few reports were published in South America and even less in human clinical isolates. Methods A total of 101 extended spectrum β-lactamase (ESBL) producing enterobacterias (87 E. coli , 11 K. pneumoniae, 1 C. freundii, 1 M. morganii, 1 E. cloacae), were collected during December, 2012 to March, 2013 from 5 health centers of Cochabamba, Bolivia. Antimicrobial susceptibility tests were performed according to CLSI recommendations. ESBL and quinolone efflux pumps determinants were investigated by PCR followed by sequencing. Clonal relatedness was investigated by REP/ERIC-PCR. The main phylogenetic groups in E. coli isolates were assessed by PCR. Results 93% (94/101) of ESBL producing isolates were resistant to quinolones (CIM NAL 32 to 64; CIP 4 to >32). Efflux pumps mechanisms were only found in few E. coli isolates (7/87) (CIM NAL >64; CIP 16 and >32). Six of them contain qepA determinant and were clustered in four different electropherotypes. A single isolate harbored the oqxAB marker. All of them were associated with CTX-M-1 group enzyme and belong to B2 phylogenetic group. Conclusions A low rate of ESBL-producing E. coli contained plasmid-mediated efflux pumps and they were associated to CTX-M-1 group cefotaximases. To our knowledge, this is the first report of oqxAB in clinical isolates of E. coli from Bolivia.