Li-Hua Li1,2, Man-San Zhang3, Chao-Jung Wu3, Yi-Tsung Lin4,5, Tsuey-Ching Yang3. 1. Department of Pathology and Laboratory Medicine, Taipei Veterans General Hospital, Taipei, Taiwan. 2. PhD Program of Medical Biotechnology, Taipei Medical University, Taipei, Taiwan. 3. Department of Biotechnology and Laboratory Science in Medicine, National Yang-Ming University, Taipei, Taiwan. 4. Division of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan. 5. School of Medicine, National Yang-Ming University, Taipei, Taiwan.
Abstract
BACKGROUND: 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. OBJECTIVES: To reveal the unidentified fluoroquinolone resistance mechanisms in S. maltophilia. METHODS: 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. RESULTS: 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. CONCLUSIONS: Overexpression of SmeGH contributes to the acquired resistance of S. maltophilia to fluoroquinolone, macrolide, chloramphenicol and tetracycline.
BACKGROUND: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. OBJECTIVES: To reveal the unidentified fluoroquinolone resistance mechanisms in S. maltophilia. METHODS: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. RESULTS: 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. CONCLUSIONS: Overexpression of SmeGH contributes to the acquired resistance of S. maltophilia to fluoroquinolone, macrolide, chloramphenicol and tetracycline.
Authors: Maria F Mojica; Romney Humphries; John J Lipuma; Amy J Mathers; Gauri G Rao; Samuel A Shelburne; Derrick E Fouts; David Van Duin; Robert A Bonomo Journal: JAC Antimicrob Resist Date: 2022-05-05