Vibrionaceae as a possible source of Qnr-like quinolone resistance determinants

Objectives: To gain insight into the functionality of qnr-like genes of several bacterial species of Vibrionaceae that may encode quinolone resistance determinants. Methods: A PCR-based strategy was used to obtain qnr-like genes of reference strains of Vibrio vulnificus CIP103196, Vibrio parahaemolyticus CIP71.2 and Photobacterium profundum CIP106289 that were sequenced, cloned and expressed in Escherichia coli. MICs of quinolones were determined for these reference strains and an E. coli reference strain harbouring recombinant plasmids. Results: The Qnr-like proteins of these Vibrionaceae bacterial species shared 40-67% amino acid identity with the plasmid-mediated quinolone resistance determinants QnrA, QnrB and QnrS with a series of highly conserved residues. Once cloned in E. coli they conferred reduced susceptibility to quinolones. Conclusions: This work provides further evidence that water-borne Vibrionaceae may constitute a reservoir for Qnr-like quinolone resistance determinants.