alterations in the lipopolysaccharide (LPS) component, and/or efflux of fluoroquinolones from bacterial cells. 5 Mutations involving the bacterial cell envelope tend to confer a multiple drug resistance phenotype to several chemically unrelated but clinically important drugs. The plasmid-encoded, integron- associated qnr gene has been sporadically found in isolates of Shigella spp., Klebsiella pneumoniae and Escherichia coli.Itis responsible for low-level fluoroquinolone resistance, especially in strains with normal OMP, and may supplement resistance due to other mechanisms such as DNA gyrase mutations, efflux pump activation or deficiencies in OMP