Characterization of Escherichia coli clinical isolates harboring QepA efflux pump isolated in South America.

RINCÓN GIOVANNA; SABA MARIELA; CEJAS DANIELA; GUTKIND GABRIEL; RADICE MARCELA; DI CONZA JOSÉ

San Diego

Conferencia; 55th ICAAC - Annual Interscience Conference on Antimicrobial Agents and Chemotherapy; 2015

American Society of Microbiology

Background: QepA is a Plasmid-Mediated Quinolone Resistance (PMQR) determinant which confers reduced susceptibility to hydrophilic fluoroquinolones, mainly ciprofloxacin and norfloxacin. This efflux pump shows considerable similarity to the major facilitator (MFS) superfamily. The high G+C content (72%) of qepA suggests that it could have been recluted from actinomycetes. Two different variants (qepA1 and qepA2) have been described. The aim of this study was to characterize eight clinical isolates of qepA-positive E. coli recovered in different countries of South America.Methods: Clinical isolates of E. coli containing qepA were collected in Argentina (A1), Peru (P1), Bolivia (B1, B2, B3, B4, B5) and Colombia (C1). 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. Clonal relatedness was investigated by REP/ERIC- PCR. The E. coli phylogenetic groups were assessed by PCR.Results: Most isolates (7/8) were resistant to nalidixic acid, ciprofloxacin, levofloxacin, and norfloxacin and they all harbored qepA1 allele. However, C1 strain, susceptible to these antibiotics, showed a new allele which displayed 99% identity to qepA1 and qepA2. ESBLs were detected in 7/8 isolates. The B1, B2, B3 B4 and B5 isolates carried blaCTX-M-15 and belonged to B2 phylogenetic group. P1 contained blaCTX-M-14, C1 harbored blaCTX-M-2 and blaCMY, and no ESBL was detected in A1. These isolates corresponded to D phylogenetic group. Other PMQR determinants were detected in A1 (qnrB10 and aac(6´)-Ib-cr) and in all isolates from Bolivia (aac(6´)-Ib-cr). The latter were clustered in three different electropherotypes.Conclusion: To our knowledge, this is the first report comparing E. coli strains containing qepA isolated in different countries of South America. They were mainly associated to diverse CTX-Ms and described in isolates that could be considered more virulent (B2 and D phylogenetic groups).