Modulation of BarA/UvrY Two-Component System Expression in Escherichia coli Induced by Ceftazidime Treatment

Abstract

Uropathogenic Escherichia coli (UPEC) remains the most common etiologic agent of community-acquired urinary tract infections (UTIs), largely due to its extensive virulence arsenal and adaptive regulatory mechanisms. In this study, we examined the phenotypic regulation of major virulence factors—hemolysin production, biofilm, swarming motility, and adhesion—under exposure to sub-inhibitory concentrations of Ceftazidime, an extended-spectrum β-lactam antibiotic. The transcriptional response of the BarA/UvrY two-component regulatory system was also examined to unravel its role in response to antibiotic stress. Using an extensive range of microbiological, molecular, and phenotypic tests, we unveiled differential profiles of virulence traits. Exposure to sub-MICs Ceftazidime markedly diminished hemolytic activity, biofilm formation, and adhesive capacity, with swarming motility exhibiting almost complete inhibition. Moreover, quantitative real-time PCR (qRT-PCR) analysis revealed variable transcriptional responses of BarA and UvrY in the tested isolates, with the recovery of BarA expression noted after prolonged exposure to antibiotics. These findings emphasize the dynamic expression of UPEC's stress response mechanisms and outline the central role of Bar/UvrY in modulating pathoadaptive mechanisms under antibiotic stress.