Pseudomonas aeruginosa develops Ciprofloxacin resistance from low to high level with distinctive proteome changes

Pseudomonas aeruginosa infection is difficult to treat because of its drug resistance, but how it develops drug resistance remains largely unknown. In this study we investigated Ciprofloxacin resistance development in P. aeruginosa. Different Ciprofloxacin concentrations selected different low level resistant mutants, and high level resistant mutants emerged from low level resistant mutants if stressed further by Ciprofloxacin. A deep quantitative proteomic study of the Ciprofloxacin resistant mutants uncovered the cellular pathways that supported such resistances. The two low level resistant mutants had different molecular mechanisms. One was mainly due to switching to anaerobic respiration and overexpression of catalase and peroxidase, and the other was probably due to iron and polyamine uptake and DNA repair. High level of resistance involved the mexCD-oprJ efflux pump and the downregulation of PQS quorum sensing. Other pathways might also have contributed to high level resistance, like the arginine deiminase pathway, catalase, peroxidase, protein degradation and DNA repair. The intracellular Ciprofloxacin concentration assay indicated that only the mexCD-oprJ overexpressed mutants had low drug accumulation. This study provided a comprehensive overview of the proteomic landscape in the evolution of Ciprofloxacin resistance in P. aeruginosa, and might have implications in diagnosis and treatment of Ciprofloxacin resistant P. aeruginosa. Data are available via ProteomeXchange with identifier PXD004560. Biological significance: Pseudomonas aeruginosa infection is difficult to treat because of its drug resistance, but how it develops drug resistance remains largely unknown. In this study we investigated Ciprofloxacin resistance development in P. aeruginosa. We found that Ciprofloxacin resistance developed from low to high level. Two different low levels resistant molecular mechanisms were discovered from different mutants selected by different Ciprofloxacin concentrations, one was mainly due to switching to anaerobic respiration and overexpression of catalase and peroxidase, the other was probably due to iron, polyamine, and DNA repair. High level of Ciprofloxacin resistance all involved the efflux pump, mexCD-oprJ, and the downregulation of quorum sensing. The findings of this study provided insights into the evolution of Ciprofloxacin resistance in P. aeruginosa and should have implications in diagnosis and treatment of Ciprofloxacin resistant P. aeruginosa. (C) 2016 Elsevier B.V. All rights reserved.