Prevalence of Plasmid Mediated Quinolone Resistance Determinants among Oxyiminocephalosporin Resistant Enterobacteriaceae

RINCÓN GIOVANNA; RADICE MARCELA; SENATTI SAMANTA; SANTELLA GISELA; PALLECCHI LUCCIA; ROSOLLINI GIAN MARIA; DI CONZA JOSÉ; GUTKIND GABRIEL

San Francisco

Congreso; 52nd Annual Interscience Conference on Antimicrobial Agents and Chemotherapy; 2012

ASM

The last decade highlighted the unexpected rise of plasmid mediated quinolone resistance determinants (PMQR). In this study we searched for the prevalence of PMQR genes within 55 different oxyiminocephalosporin resistant enterobacteria during one week of October 2010 at 15 hospitals distributed in Argentina. Antimicrobial susceptibility tests were performed accordingly to CLSI. Screening for ESBL and AmpC were conducted by double disk synergy tests. ESBL and PMQR determinants were investigated by PCR followed by sequencing and/or RFLP-PCR using BseGI. ESBL production was confirmed in 50/55 oxyiminocephalosporin resistant isolates, from them, 47 were CTX-M producers (94%). Susceptibility to nalidixic acid and also ciprofloxacin was 7,27% and the rate of susceptible isolates to either levofloxacin or gatifloxacin was 23.6%. Gentamicin, amikacin and tobramycin displayed 43.6%, 61.8% and 23.6% susceptibility, respectively. qnrB2 was associated to blaCTX-M-15 (4), blaCTX-M-2 (2) and blaCTX-M-14 (2); while qnrB19 to blaCTX-M-2 (4), blaCTX-M-15 (1) and both blaCTX-M-15/blaCTX-M-2 (1). qnrB10 was linked to blaCTX-M-2 (2) and blaPER/blaSHV (1). Finally qnrB6 was associated with blaCTX-M-2 (1) and qnrB1 with blaCTX-M-15 (1). Not a single isolate rendered a positive amplification for qnrA, qnrS, qnrC, qnrD and qepA. In addition, aac(6´)-Ib-cr was detected in 40% (22/55) isolates mainly associated with blaCTX-M-15 (14) and to a lesser extend to other CTX-M coding genes, blaCTX-M-2 (5), blaCTX-M-15/CTX-M-2 (1), blaCTX-M-14 (1) and blaCTX-M-8 (1). High quinolone resistance rates were observed among oxyiminocephalosporin resistant enterobacteria. The main PMQR determinants were aac(6´)-Ib-cr and qnrB corresponding to 40% and 34.5%, respectively. It could be noted that AAC(6?)-Ib-cr was more frequently present in CTX-M-15 producing isolates, while QnrB is homogeneously distributed in all CTX-M