Identification of two novel type II topoisomerase mutations in Enterococcus spp. isolated from a hospital in China

Type II topoisomerases, including DNA gyrase (GyrA) and topoisomerase IV (ParC), contribute to fluoroquinolone resistance in Enterococcus spp. This study investigated the mutational status of quinolone resistance-determining regions (QRDRs) GyrA ParC clinical isolates enterococci from a hospital Baotou, China. We analyzed 110 enterococcal isolates, 57 faecalis 53 faecium. The rates E. faecium ciprofloxacin were 63.16% 84.91%, respectively. found that 32 samples 42 had single or combined mutations gyrA and/or parC, which all resistant ciprofloxacin. Only two ciprofloxacin-resistant no mutation. No parC genes ciprofloxacinsusceptible found. Ciprofloxacin minimal inhibitory concentrations (MICs) mutation group significantly higher than those non-mutation group, indicating QRDRs correlated with MIC elevation. Two novel substitutions (GyrA Ser83Phe Ser80Leu) identified herein. Three-dimensional modeling revealed these amino acid could disrupt water/metal-ion bridge decrease interaction between enzymes data showed diversity types type topoisomerases whose association warrants further investigation.