Detection of fluoroquinolones resistance in enterobacteriaceae and pseudomonas species using molecular techniques

ABSTRACT

Background: quinolone resistance is traditionally mediated by chromosomal mutations mutation of DNA gyrase and/or topoisomerase IV or by the mutation of genes regulating the expression of efflux pumps, until PMQR was described in a clinical isolate of Klebsiella pneumoniae in 1998. PMQR genes generally confer low-level resistance, with their MICs falling below Clinical and Laboratory Standards Institute [CLSI] breakpoints for intermediate resistance; therefore, their contribution to quinolone resistance can be masked in strains also harboring QRDR mutations in gyrA and parC. However, their clinical significance stems from the fact that they greatly facilitate the selection of more highly quinolone-resistant strains. Although the PMQR mechanism only confers low-level resistance to FQs, its association with the occurrence of mutations in QRDR can lead to clinically relevant resistance levels. These PMQR determinants are increasingly being identified worldwide in clinical isolates of Enterobacteriaceae and Pseudomonas spp