DNA Gyrase gyrA Mutations in Quinolone-Resistant Clinical Isolates of Staphylococcus haemolyticus

Staphylococci are significant human pathogens. Coagulase-positive Staphylococcus aureus causes a variety of infections. Recently, coagulase-negative staphylococci have been recog-nized as important pathogens. Fluoroquinolones have been widely used to treat staphylococcal infections. However, quin-olone-resistant strains have been clinically isolated among S. aureus and Staphylococcus epidermidis. One of the mechanisms of resistance to quinolones is an alteration of DNA gyrase. DNA gyrase contains the two sub-units of GyrA and two subunits of GyrB encoded by the gyrA and gyrB genes, respectively. DNA gyrase catalyzes ATP-de-pendent supercoiling of DNA and is a target of the quinolones (3). Ser-843Leu, Ser-843Ala, Ser-853Pro, Glu-883Gly, and Glu-883Lys changes were identified in S. aureusGyrA (1) and a Ser-843Phe mutation was observed in S. epidermidi