Fluoroquinolone resistance

Abstract

Fluoroquinolones are highly active, broad spectrum antibiotics with many uses in both human and veterinary medicine. As with other classes of antibiotic, however, decreased susceptibility or resistance to these agents has developed. Resistance is usually chromosomally mediated so the spread of resistant bacteria contributes to the high numbers of resistant strains reported by some institutions. Although for many infections the changes in susceptibility of the bacteria have not had an immediate clinical impact, highly resistant strains have recently emerged. For some infections and bacterial species the clinical usefulness of fluoroquinolones may be limited if their use is not curtailed. Genetic and biochemical experiments have shown two enzymes that are the targets of fluoroquinolones.1 In Gram negative bacteria such as Escherichia coli , Pseudomonas aeruginosa, and Neisseria gonorrhoea ,the primary target is DNA gyrase and the secondary target DNA topoisomerase IV; in Gram positive bacteria, such as Staphylococcus aureus and S pneumoniae , the primary and secondary targets are reversed.2 DNA gyrase and topoisomerase IV are each enzymes composed of four subunits (two A and two B) encoded by gyrA and gyrB ,and parC and parE respectively. Fluoroquinolone resistant isolates …