King's College London, Department of Infectious Diseases, Division of Immunology, Infection and Inflammatory Diseases, School of Medicine, London SE1 7EH, UK.
Eur J Clin Microbiol Infect Dis. 2011 Jun;30(6):745-52. doi: 10.1007/s10096-010-1147-0. Epub 2011 Feb 1.
We investigated the prevalence and role of efflux pump activity and possible drug influx resistance in ciprofloxacin susceptibility amongst 26 distinct clinical isolates of Klebsiella pneumoniae of varying ciprofloxacin susceptibilities and known quinolone resistance-determining region (QRDR) genotypes. Cellular [(14)C]ciprofloxacin accumulation patterns and the amount of cell-associated [(14)C]ciprofloxacin of mid-logarithmic phase cells were determined before and after challenging with the efflux pump inhibitor carbonyl cyanide 3-chlorophenylhydrazone (CCCP). Most isolates (24/26), and all with ciprofloxacin minimum inhibitory concentrations (MICs) >1 µg/ml, had efflux activity that could extrude up to 90% of cell-associated [(14)C]ciprofloxacin; none had significant influx resistance. In isolates with no QRDR mutations, efflux alone reduced ciprofloxacin susceptibility. In isolates with QRDR mutations, the efflux activity varied: in one isolate with no efflux activity, the most common fluoroquinolone resistance-causing QRDR mutation did not bring about clinically significant ciprofloxacin resistance; isolates with multiple mutations had high MICs and, usually, high levels of efflux activity. Fluoroquinolone efflux activity is much more common in clinical isolates of K. pneumoniae than previously reported and it can contribute to decreased ciprofloxacin susceptibility.
我们调查了 26 株不同的肺炎克雷伯菌临床分离株中，与氟喹诺酮类药物敏感性相关的外排泵活性和药物摄取耐药性的流行情况和作用，这些分离株对环丙沙星的敏感性不同，并且已知存在喹诺酮类药物耐药决定区（QRDR）基因型。在使用外排泵抑制剂羰基氰化物 3-氯苯腙（CCCP）对对数中期细胞进行挑战前后，测定了细胞内[14C]环丙沙星的积累模式和细胞结合[14C]环丙沙星的量。大多数分离株（24/26），以及所有环丙沙星最小抑菌浓度（MIC）>1μg/ml 的分离株，均具有外排活性，可将高达 90%的细胞结合[14C]环丙沙星排出；没有明显的摄取耐药性。在没有 QRDR 突变的分离株中，单独的外排作用就降低了环丙沙星的敏感性。在具有 QRDR 突变的分离株中，外排活性不同：在一个没有外排作用的分离株中，最常见的导致氟喹诺酮类药物耐药的 QRDR 突变并没有导致临床上显著的环丙沙星耐药；具有多种突变的分离株具有较高的 MIC 值，通常也具有较高的外排活性。氟喹诺酮类药物外排活性在肺炎克雷伯菌的临床分离株中比以前报道的更为常见，它可以导致环丙沙星敏感性降低。
