南京农业大学学报2009，Vol.32Issue(4)：133-137,5.
人工诱导猪链球菌氟喹诺酮耐药株的靶位突变分析
Mutation analysis of induced fluoroquinolone-resistant mutants of Streptococcus suis in vitro
摘要
Abstract
To perform a systematic analysis of point mutations in the quinolone resistance determining regions (QRDRs) of the DNA gyrase and topoisomerase genes of Streptococcus suis type 2 strain after in vitro exposure to stepwise increasing concentrations of enrofloxacin and ciprofloxacin. Four parent strains of S. suis type 2 were chosen for stepwise exposure to increasing levels of enro-floxacin and ciprofloxacin followed by selection of resistant mutants. The QRDRs of gyrA, gyrB, parC and parE correlating to mutants with increased MICs were analysed for point mutations. Multiple mutants with significantly increased MICs (128 mg· L~(-1)) were generated from each parent strain. Most of the amino acid substitutions identified were Ser79Phe of ParC, Ser81 Arg of GyrA, Asp315Asn, Ser285Leu, Glu354Lys of GryB and Pro278Ser of ParE, which were consistent to the mechanisms of resistance reported in clinical isolates of S. pneumoniae. However, it has some mutable points Glnll8His of GyrA, Asn297Tyr of ParE as well as the deletions 288 -291 amino acids of GyrB and 62 amino acid of ParC, which haven't been documented and whether these nuleoti-de mutations associated with fluoroquinolone resistance are not clear. The number of induction/selection cycles required for the emergence of key point mutations in gyrA and parC was variable among strains. The results indicate that stepwise increasing concentration of enrofloxacin and ciprofloxacin can easily select resistant strains of S. suis.关键词
恩诺沙星/环丙沙星/猪链球菌2/DNA回旋酶/拓扑异构酶Ⅳ/靶位突变Key words
enrofloxacin/ciprofloxacin/Streptococcus suis type 2/DNA gyrase/topoisomerase Ⅳ/target mutation分类
医药卫生引用本文复制引用
张雨菡,姚杰,陆承平,王丽平..人工诱导猪链球菌氟喹诺酮耐药株的靶位突变分析[J].南京农业大学学报,2009,32(4):133-137,5.基金项目
公益性行业(农业)科研专项(200803016) （农业）
