Characterization of Three Clinical isolates of Escherichia coli Carrying oqxAB Genes.

RINCÓN GIOVANNA; RADICE MARCELA; SEVILLA ANDRADE, CARLOS; PURAY CHAVEZ, MARITZA; DI CONZA JOSÉ; GUTKIND GABRIEL

Washington

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

American Society of Microbiology

Background: oqxAB was initially detected in Escherichia coli from swine manure. Although its prevalence in human isolates is still very scarcely reported, an incidence of 6.6% was found in China in 2012. The aim of this study was to characterize three E. coli, carrying oqxAB obtained from patients treated at hospitals at the metropolitan area in Lima, during January 2011. Methods: Presence of the PMQR genes (qnrA, qnrB, qnrS, qnrC, qnrD, qnrVC, qepA, oqxA, oqxB and aac(6´)-Ib-cr) and QRDR mutations were determined by PCR and sequencing. After purifying the plasmidic content of each isolate, electro-transformants were selected. S1 nuclease- PFGE and Southern blotting experiments were performed to investigate the oqxAB location. Plasmid incompatibility groups were determined by PCR based replicon typing. The clonal relatedness was investigated by PFGE with XbaI and MLST. The association of IS26 with oqxAB was investigated by PCR mapping. Results: The three isolates were resistant to nalidixic acid, ciprofloxacin, levofloxacin and gatifloxacin. Two were indistinguishable by PFGE and belonged to ST602 (ER2 and ER3) and one (DAC3) corresponded to ST448. A bla CTX-M-9 group was detected in ER2 and DAC3 and a CTX-M-1 group in ER3. CTX-M plasmids corresponded to IncI1 replicon type in all cases. Two mutations in GyrA (S83L, D87N) and one in ParC (S80I) were observed in all isolates. oqxA gene was flanked upstream by IS26 and located in a 100-kb plasmid that could be transferred, in ER2 and ER3. oqxAB containing plasmid from DAC3 could not be transferred and it was located in a approximately 90kb plasmid. All plasmids harboring oqxAB corresponded to IncFIB/ IncK/IncF replicon type. ER3 also harbored aac(6´)-Ib-cr; no other PMQR were detected. Conclusion: This is the first report of oqxAB in human clinically relevant E. coli from America. Besides one strain co-carried oqxAB and aac(6´)-Ib-cr. Our results revealed that oqxAB and CTX-M- are located in different plasmids in all the cases.