Yagüe Guirao G, Martínez-Toldos M C, Alonso Manzanares M A, Gutiérrez Zufiaurre M N, Martínez-Andrés J A, Muñoz Bellido J L, García-Rodríguez J A, Segovia Hernández M
Departamento de Genética y Microbiología, Facultad de Medicina, Universidad de Murcia.
Rev Esp Quimioter. 2000 Sep;13(3):271-5.
The aim of this study was to determine the in vitro activity of five quinolones against clinical strains of methicillin-susceptible and -resistant Staphylococcus aureus clinical isolates characterized at the molecular level with respect to the presence of mutations in genes coding for resistance to quinolones (grlA, gyrA and gyrB). The relationship between the mutations found and the activities of these quinolones was also analyzed. Trovafloxacin was the most active against methicillin-susceptible S. aureus and showed good activity against methicillin-resistant S. aureus, with a MIC90 of 2 mg/l. The grlA-gyrA double mutation was the most frequent (55% of the strains). Single mutation in grlA was detected only in 5% of strains; 39% of strains showed a wild-type genotype. The grlA-gyrA double mutants presented a high level of resistance against the fluoroquinolones tested except for trovafloxacin, with the MIC ranging between 0.5 and 4 mg/l. Wild-type strains were susceptible to all the fluoroquinolones tested and the single grlA mutants had a low level of quinolone resistance but were still below the breakpoint for resistance. Trovafloxacin and sparfloxacin were less affected by this mutation.
本研究的目的是确定五种喹诺酮类药物对甲氧西林敏感和耐药金黄色葡萄球菌临床分离株的体外活性，这些分离株在分子水平上根据编码对喹诺酮类药物耐药性的基因（grlA、gyrA和gyrB）中的突变情况进行了表征。还分析了所发现的突变与这些喹诺酮类药物活性之间的关系。曲伐沙星对甲氧西林敏感金黄色葡萄球菌活性最强，对甲氧西林耐药金黄色葡萄球菌也表现出良好活性，MIC90为2mg/l。grlA-gyrA双突变最为常见（占菌株的55%）。仅在5%的菌株中检测到grlA单突变；39%的菌株表现出野生型基因型。除曲伐沙星外，grlA-gyrA双突变体对所测试的氟喹诺酮类药物呈现高水平耐药，MIC范围在0.5至4mg/l之间。野生型菌株对所有测试的氟喹诺酮类药物敏感，grlA单突变体对喹诺酮类药物耐药水平较低，但仍低于耐药断点。曲伐沙星和司帕沙星受此突变的影响较小。
