Price Lance B, Vogler Amy, Pearson Talima, Busch Joseph D, Schupp James M, Keim Paul
Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona 86011-5640, USA.
Antimicrob Agents Chemother. 2003 Jul;47(7):2362-5. doi: 10.1128/AAC.47.7.2362-2365.2003.
Mutants of attenuated Bacillus anthracis with high-level ciprofloxacin resistance were isolated using a three-step in vitro selection. Ciprofloxacin MICs were 0.5 micro g/ml for first-step mutants, which had one of two gyrA quinolone resistance-determining region (QRDR) mutations. Ciprofloxacin MICs were 8 and 16 microg/ml for second-step mutants, which had one of three parC QRDR mutations. Ciprofloxacin MICs for third-step mutants were 32 and 64 microg/ml. Mutants for which MICs were 64 microg/ml had one of two additional mutations within the gyrA QRDR or one of two mutations within the gyrB QRDR. Mutants for which MICs were 32 microg/ml had no additional target modifications but showed evidence of enhanced ciprofloxacin efflux.
通过三步体外筛选分离出了对环丙沙星具有高水平耐药性的减毒炭疽芽孢杆菌突变体。第一步突变体的环丙沙星最低抑菌浓度(MIC)为0.5微克/毫升,其gyrA喹诺酮耐药决定区(QRDR)有两种突变之一。第二步突变体的环丙沙星MIC为8和16微克/毫升,其parC QRDR有三种突变之一。第三步突变体的环丙沙星MIC为32和64微克/毫升。MIC为64微克/毫升的突变体在gyrA QRDR内有另外两种突变之一,或在gyrB QRDR内有两种突变之一。MIC为32微克/毫升的突变体没有额外的靶点修饰,但显示出环丙沙星外排增强的迹象。