Synergistic action of singlet oxygen and antibiotics against extensively drug-resistant Enterobacterales

Gram-negative microorganisms pose a significant threat due to the dwindling availability of effective antibiotics. Antimicrobial photodynamic inactivation, which relies on singlet oxygen production, could be a potential strategy for sensitizing drug-resistant strains. Within our study, we examined whether singlet oxygen generated via application of rose Bengal and green light can led to increased susceptibility of extensively drug-resistant Enterobacterales. Exposure of Enterobacterales to singlet oxygen in the PBS environment resulted in the changes in the resistance profile, especially in the case of the clinical isolate of E. coli KPD860. Synergy between antibiotics and aPDI occurred differentially between extensively drug-resistant strains. Exposure of clinical isolates to singlet oxygen increased the susceptibility of Escherichia coli KPD860 to tigecycline, imipenem, and ceftazidime combined with clavulanic acid. However, this effect was different between the other tested bacterial isolates.