Detection of QnrB54 and its novel genetic context in Citrobacter freundii isolated from a clinical case.

Quinolone resistance in Enterobacteriaceae is mediated by mutations in the quinolone resistance-determining regions (QRDR) of topoisomerase genes and/or by plasmid-mediated quinolone resistance determinants (PMQR) such as the qnr genes encoding pentapeptide repeat proteins ([1][1]). The qnrB family