Zhanel George G, Walkty Andrew, Nichol Kim, Smith Heather, Noreddin Ayman, Hoban Daryl J
Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada.
Diagn Microbiol Infect Dis. 2003 Jan;45(1):63-7. doi: 10.1016/s0732-8893(02)00498-4.
There is little published data detailing fluoroquinolone resistance in clinical isolates of S. pneumoniae. The purpose of this study was to characterize the resistance mechanisms of 34 fluoroquinolone-resistant S. pneumoniae clinical isolates obtained from medical centers in 8 of 10 Canadian provinces between 1997 and 2000. The quinolone resistance determining regions of gyrA, parC, and parE from the isolates were sequenced. The isolates were evaluated for reserpine-sensitive efflux of ciprofloxacin and the new fluoroquinolones: gatifloxacin, gemifloxacin, levofloxacin and moxifloxacin. The isolates were typed using pulsed field gel electrophoresis. The majority of the isolates were genetically unrelated. Lower level fluoroquinolone resistance (ciprofloxacin MIC 4-8 microg/ml) was associated with amino acid substitutions in ParC, while higher level resistance (ciprofloxacin MIC > or = 16 microg/ml) was associated with amino acid substitutions in both ParC and GyrA. ParE substitutions were not associated with clinical resistance. Twelve of 34 (35%) isolates demonstrated reserpine-sensitive efflux of ciprofloxacin. Efflux alone conferred low level ciprofloxacin resistance in 3 isolates. Significant reserpine-sensitive efflux of the new fluoroquinolones was not observed.
关于肺炎链球菌临床分离株中氟喹诺酮耐药性的详细公开数据很少。本研究的目的是对1997年至2000年间从加拿大10个省中的8个省的医疗中心获得的34株耐氟喹诺酮肺炎链球菌临床分离株的耐药机制进行表征。对分离株的gyrA、parC和parE的喹诺酮耐药决定区进行测序。评估分离株对利血平敏感的环丙沙星及新氟喹诺酮类药物（加替沙星、吉米沙星、左氧氟沙星和莫西沙星）外排情况。使用脉冲场凝胶电泳对分离株进行分型。大多数分离株在基因上不相关。较低水平的氟喹诺酮耐药性（环丙沙星MIC为4 - 8μg/ml）与ParC中的氨基酸替换有关，而较高水平的耐药性（环丙沙星MIC≥16μg/ml）与ParC和GyrA中的氨基酸替换有关。ParE替换与临床耐药性无关。34株分离株中有12株（35%）表现出对利血平敏感的环丙沙星外排。仅外排在3株分离株中导致低水平的环丙沙星耐药。未观察到新氟喹诺酮类药物有明显的对利血平敏感的外排情况。
