Novel mutations in the QRDR region gyrA gene in multidrug-resistance Corynebacterium spp. isolates from intravenous sites.

The resistance to fluoroquinolones in corynebacteria is due to mutations occurring in the quinolone-resistance-determining region (QRDR) of the gyrA gene encoding the enzyme gyrase A subunit. In recent years we can observe an increasing number of infections caused by multidrug-resistant Corynebacterium striatum, Corynebacterium jeikeium and Corynebacterium urealyticum, including wide range of disorders, such as invasive infections. In this study 14 Corynebacterium spp. isolated from intravenous sites were sequenced and new combinations of mutations in the QRDR of the gyrA gene were found in C. jeikeium and C. urealyticum. Nowadays, no study comparing mutations in this region and the susceptibility to fluoroquinolones in C. jeikeium and C. urealyticum has been described. All the isolates that showed double mutation (position 87 and 91) in the QRDR gyrA gene had high MIC to the fluoroquinolones tested.