Zając Olga M, Tyski Stefan, Laudy Agnieszka E
Department of Pharmaceutical Microbiology, Medical University of Warsaw, 02-097 Warsaw, Poland.
Department of Antibiotics and Microbiology, National Medicines Institute, 00-725 Warsaw, Poland.
Biology (Basel). 2022 Jul 12;11(7):1044. doi: 10.3390/biology11071044.
Levofloxacin is considered an alternative treatment option of infections to trimethoprim/sulfamethoxazole. The fluoroquinolone resistance in is usually caused by an overproduction of efflux pumps. In this study, the contribution of efflux systems to levofloxacin resistance in clinical isolates was demonstrated using phenotypic (minimal inhibitory concentrations, MICs, of antibiotics determination ± efflux pump inhibitors, EPIs) and molecular (real-time polymerase-chain-reaction and sequencing) methods. Previously, the occurrence of genes encoding ten efflux pumps was shown in 94 studied isolates. Additionally, 44/94 isolates demonstrated reduction in susceptibility to levofloxacin. Only 5 of 13 isolates (with ≥4-fold reduction in levofloxacin MIC) in the presence of EPIs showed an increased susceptibility to levofloxacin and other antibiotics. The overexpression of and genes (in five and one isolate, respectively) of 5 tested efflux pump operons was demonstrated. Sequencing analysis revealed 20-35 nucleotide mutations in local regulatory genes such as and . However, mutations leading to an amino acid change were shown only in (Arg123Lys, Asp182Glu, Asp204Glu) for one isolate and in (Gly266Ser) for the other isolate. Our data indicate that the overproduction of the SmeVWX efflux system, unlike SmeDEF, plays a significant role in the levofloxacin resistance.
左氧氟沙星被认为是治疗感染的一种替代甲氧苄啶/磺胺甲恶唑的选择。铜绿假单胞菌中的氟喹诺酮耐药性通常是由外排泵过度产生所致。在本研究中，使用表型方法（测定抗生素的最低抑菌浓度，MIC，±外排泵抑制剂，EPI）和分子方法（实时聚合酶链反应和测序）证明了外排系统对铜绿假单胞菌临床分离株左氧氟沙星耐药性的影响。此前，在94株研究分离株中显示了编码十种外排泵的基因的存在。此外，44/94株分离株对左氧氟沙星的敏感性降低。在存在EPI的情况下，13株分离株中只有5株（左氧氟沙星MIC降低≥4倍）对左氧氟沙星和其他抗生素的敏感性增加。证明了5个测试的外排泵操纵子的mexAB-oprM和mexCD-oprJ基因（分别在5株和1株分离株中）的过表达。测序分析揭示了局部调控基因如ramR和marR中的20 - 35个核苷酸突变。然而，仅在一株分离株的mexR（Arg123Lys、Asp182Glu、Asp204Glu）和另一株分离株的marR（Gly266Ser）中显示出导致氨基酸变化的突变。我们的数据表明，与SmeDEF不同，SmeVWX外排系统的过度产生在左氧氟沙星耐药性中起重要作用。
