Department of Pathology and Laboratory Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
PhD Program of Medical Biotechnology, Taipei Medical University, Taipei, Taiwan.
J Antimicrob Chemother. 2019 Aug 1;74(8):2225-2229. doi: 10.1093/jac/dkz200.
Stenotrophomonas maltophilia displays high-level resistance to various antibiotics. Fluoroquinolone is among the few treatment options for S. maltophilia infection. Overexpression of SmeDEF, SmeVWX and SmQnr are the main mechanisms responsible for fluoroquinolone resistance in S. maltophilia.
To reveal the unidentified fluoroquinolone resistance mechanisms in S. maltophilia.
Fluoroquinolone-resistant spontaneous mutants were selected by spreading KJΔDEFΔ5, a SmeDEF- and SmeVWX-null double mutant, on ciprofloxacin- or levofloxacin-containing medium. Antibiotic susceptibility was assessed by the agar dilution method. Outer membrane protein profiles of fluoroquinolone-resistant mutants were assayed by SDS-PAGE and significant protein was characterized by LC-MS/MS. The expression of tolCsm, smeH, smeK, smeN, smeP, smeZ and smQnr was investigated by real-time quantitative PCR. The contribution of SmeGH overexpression to antibiotic resistance was verified by ΔsmeH mutant construction and smeGH complementation assay.
Most fluoroquinolone-resistant mutants displayed MDR. The TolCsm protein and smeH transcript were concomitantly overexpressed in some MDR mutants. smeH deletion increased the susceptibility of the MDR mutants to fluoroquinolone, macrolide, chloramphenicol and tetracycline, and the resistance compromise was partially reversed by complementation with a plasmid containing smeGH. SmeGH overexpression was found in some fluoroquinolone-resistant clinical S. maltophilia isolates whose SmeDEF, SmeVWX and SmQnr proteins were not or were lowly expressed.
Overexpression of SmeGH contributes to the acquired resistance of S. maltophilia to fluoroquinolone, macrolide, chloramphenicol and tetracycline.
嗜麦芽窄食单胞菌对各种抗生素表现出高水平的耐药性。氟喹诺酮类药物是治疗嗜麦芽窄食单胞菌感染的少数选择之一。SmeDEF、SmeVWX 和 SmQnr 的过表达是嗜麦芽窄食单胞菌对氟喹诺酮类药物耐药的主要机制。
揭示嗜麦芽窄食单胞菌中未识别的氟喹诺酮类耐药机制。
通过在含有环丙沙星或左氧氟沙星的培养基上扩散 SmeDEF 和 SmeVWX 缺失的双突变体 KJΔDEFΔ5 来选择氟喹诺酮类药物耐药自发突变体。通过琼脂稀释法评估抗生素敏感性。通过 SDS-PAGE 测定氟喹诺酮类耐药突变体的外膜蛋白图谱，并通过 LC-MS/MS 对显著蛋白进行表征。通过实时定量 PCR 研究 tolCsm、smeH、smeK、smeN、smeP、smeZ 和 smQnr 的表达。通过构建ΔsmeH 突变体和 smeGH 互补实验验证 SmeGH 过表达对抗生素耐药性的贡献。
大多数氟喹诺酮类耐药突变体表现出 MDR。一些 MDR 突变体中同时过表达 TolCsm 蛋白和 smeH 转录本。smeH 缺失增加了 MDR 突变体对氟喹诺酮类、大环内酯类、氯霉素和四环素的敏感性，并且通过含有 smeGH 的质粒互补部分逆转了耐药性。在一些氟喹诺酮类耐药的临床嗜麦芽窄食单胞菌分离株中发现了 SmeGH 的过表达，这些分离株的 SmeDEF、SmeVWX 和 SmQnr 蛋白未表达或低表达。
SmeGH 的过表达导致嗜麦芽窄食单胞菌对氟喹诺酮类、大环内酯类、氯霉素和四环素的获得性耐药。
