Exogenous Pyocyanin Alters Pseudomonas aeruginosa Susceptibility to Ciprofloxacin

Abstract

This in vitro cell-based study identified the contributing role of pyocyanin in the resistance of Pseudomonas aeruginosa to ciprofloxacin. Problem statement: P. aeruginosa is the major pathogen in the Cystic Fibrosis (CF) lung with pyocyanin being a critical component of its virulence. Prevalence is high and, once acquired, chronic infection is difficult to eliminate. Ciprofloxacin remains a crucial oral agent effective against P. aeruginosa, but resistance is increasingly reported. Approach: Here we examined the extent to which exogenously added pyocyanin affected P. aeruginosa susceptibility to ciprofloxacin and the contribution of altered efflux activity and biofilm production with the aim of ultimately increasing sensitivity. Results: Metabolic conversion of resazurin to resorufin was used as an index of bacterial cell growth while fluorescent measurement of acriflavine efflux and crystal violet staining was used as markers of efflux activity and biofilm production, respectively. Pyocyanin (100