Maple P A, Hamilton-Miller J M, Brumfitt W
Department of Medical Microbiology, Royal Free Hospital School of Medicine, London, United Kingdom.
Antimicrob Agents Chemother. 1991 Feb;35(2):345-50. doi: 10.1128/AAC.35.2.345.
The in vitro activities of nine quinolones (seven fluoroquinolones, nalidixic acid, and acrosoxacin) against methicillin-resistant Staphylococcus aureus (MRSA) were compared with those of the glycopeptides teicoplanin and vancomycin. MICs against 160 strains of ciprofloxacin-susceptible (MIC, less than 2.0 micrograms/ml) MRSA and 40 strains of ciprofloxacin-resistant (MIC, greater than or equal to 2.0 micrograms/ml) MRSA were determined. The following MICs for 50% of the strains tested (in micrograms per milliliter) were obtained for ciprofloxacin-susceptible and -resistant strains, respectively: tosufloxacin, 0.06 and 2.0; ofloxacin, 0.25 and 16; ciprofloxacin, 0.5 and 16; pefloxacin, 0.5 and 32; acrosoxacin, 1.0 and greater than 256; enoxacin, 1.0 and 64; fleroxacin, 1.0 and 32; norfloxacin, 2.0 and 64; nalidixic acid, 64 and 512; teicoplanin, 1.0 and 1.0; vancomycin, 2.0 and 2.0. In mutation rate studies using a range of antibiotic concentrations to reflect those achievable in vivo, resistant mutants grew only on plates containing nalidixic acid (rate of mutation to resistance, 10(-7) to 10(-8) and on plates containing low concentrations of ciprofloxacin, enoxacin, and norfloxacin (rate of mutation to resistance, 10(-8) to 10(-9). In time-kill studies, 99.9% killing was found within 8 h for all of the quinolones tested (norfloxacin and nalidixic acid were not tested). Teicoplanin and vancomycin were less rapidly bactericidal. For the clinical isolates of ciprofloxacin-resistant MRSA, different levels and patterns of quinolone resistance were found. Generally, cross-resistance among the fluoroquinolones was complete; however, incomplete cross-resistance did occur with the nonfluorinated quinolone acrosoxacin.
将9种喹诺酮类药物（7种氟喹诺酮类、萘啶酸和阿克罗沙星）对耐甲氧西林金黄色葡萄球菌（MRSA）的体外活性与糖肽类药物替考拉宁和万古霉素进行了比较。测定了对160株对环丙沙星敏感（MIC，小于2.0微克/毫升）的MRSA和40株对环丙沙星耐药（MIC，大于或等于2.0微克/毫升）的MRSA的MIC。对测试的50%菌株（以微克/毫升计），对环丙沙星敏感和耐药菌株分别获得以下MIC：妥舒沙星，0.06和2.0；氧氟沙星，0.25和16；环丙沙星，0.5和16；培氟沙星，0.5和32；阿克罗沙星，1.0和大于256；依诺沙星，1.0和64；氟罗沙星，1.0和32；诺氟沙星，2.0和64；萘啶酸，64和512；替考拉宁，1.0和1.0；万古霉素，2.0和2.0。在使用一系列抗生素浓度以反映体内可达到浓度的突变率研究中，耐药突变体仅在含有萘啶酸的平板上生长（耐药突变率为10^(-7)至10^(-8)）以及在含有低浓度环丙沙星、依诺沙星和诺氟沙星的平板上生长（耐药突变率为10^(-8)至10^(-9)）。在时间-杀菌研究中，所有测试的喹诺酮类药物（未测试诺氟沙星和萘啶酸）在8小时内均发现有99.9%的杀菌率。替考拉宁和万古霉素的杀菌速度较慢。对于环丙沙星耐药的MRSA临床分离株，发现了不同水平和模式的喹诺酮类耐药。一般来说，氟喹诺酮类之间的交叉耐药是完全的；然而，与非氟化喹诺酮阿克罗沙星确实发生了不完全交叉耐药。
