Phenotypic Effects of a Small Molecule CpxA Phosphatase Inhibitor on Uropathogenic Escherichia coli

Patients suffering from Urinary Tract Infections (UTIs) are faced with multidrug resistance and a lack of treatment options. An alternative strategy to traditional bactericidal drug design is to disarm pathogenic bacteria by targeting the regulation of virulence factors. Small-molecule CpxRA phosphatase inhibitor compound 26, hereafter referred to as Cpx26, has shown efficacy in a murine UTI model; however, the impact of pharmacological modulation of CpxRA on bacterial physiology is undefined. Herein, we report the activity of Cpx26 in phenotypic assays to provide insight into its mechanism of action and antivirulence properties. Cpx26 significantly inhibited swimming motility, biofilm formation, and adhesion to bladder epithelial cells at concentrations >60-fold below its MIC. Combination with first-line UTI antibiotics was explored, and synergy was observed with trimethoprim/sulfamethoxazole and fosfomycin, implying potential clinical benefit. This work highlights the potential of antivirulence therapies for prevalent infections such as UTIs.