The impact of antioxidant-ciprofloxacin combinations on the evolution of antibiotic resistance in Pseudomonas aeruginosa biofilms
Doaa Higazy, Marwa N. Ahmed, Oana Ciofu
Abstract
The evolution of antimicrobial resistance (AMR) in biofilms, driven by mechanisms like oxidative stress, is a major challenge. This study investigates whether antioxidants (AOs) such as N-acetyl-cysteine (NAC) and Edaravone (ED) can reduce AMR in Pseudomonas aeruginosa biofilms exposed to sub-inhibitory concentrations of ciprofloxacin (CIP). In vitro experimental evolution studies were conducted using flow cells and glass beads biofilm models. Results showed that combining CIP with antioxidants (CIP-AOs) effectively reduced the development of CIP resistance. Isolates from biofilms treated with CIP-AO had significantly lower minimum inhibitory concentrations (MICs) of CIP compared to those treated with CIP alone. Whole-genome sequencing (WGS) revealed mutations in the negative regulators of efflux pumps, nfxB, and nalC, in CIP-only treated biofilm populations. The occurrence of nfxB mutations was significantly lower in flow cell biofilms treated with CIP-AO compared to CIP alone. These findings suggest that antioxidants could play a role in mitigating AMR development in biofilms.