Insights into Pseudomonas aeruginosa ATCC9027 resistance to isothiazolones through proteomics

Although many explanations have been proposed for drug resistance to isothiazolones, the scope of cellular and physiological changes associated with this resistance remains unclear. In this study, comparative proteomic profiles of Pseudomonas aeruginosa ATCC9027 (WT) and an induced strain of Pa-R, which showed resistance to Kathon (a type of isothiazolone), were characterized using two-dimensional electrophoresis and matrix-assisted desorption/ionization time-of-flight mass spectroscopy. The results showed that a total of 16 proteins were successfully identified, among which 5 proteins were upregulated and 11 proteins were found to be repressed in Pa-R. At the same time, there were 14 proteins that contributed to metabolic processes, 1 protein (ATP-binding component of ATP-binding cassette [ABC] transporter) was the cellular component, and 1 protein (LolA) exhibited a transporter activity. The respective gene expression patterns of all the identified proteins in both Pa-R and WT were also evaluated by quantitative real-time polymerase chain reaction and shown to consistently correlate with those deduced from the proteomic results. Moreover, the resistant levels of Pa-R and WT could be affected by temperature and pH. Additionally, Pa-R exhibited coresistance and cross-resistance to other types of antimicrobial agents. Our results suggest that the resistant levels of P. aeruginosa to isothiazolones could be affected by extracellular factors and the resistance features are a complex system.