Blue Light Compromises Bacterial β-Lactamases Activity to Overcome β-Lactam Resistance.

Area of Science:

• Photomedicine
• Antimicrobial resistance research
• Biochemistry

Background:

• β-lactamase enzymes confer resistance to β-lactam antibiotics.
• Antimicrobial blue light (aBL) is an emerging therapeutic modality.
• Investigating aBL's efficacy against resistant bacteria is crucial.

Purpose of the Study:

• To evaluate the effectiveness of antimicrobial blue light (aBL) against β-lactamase-producing bacteria.
• To determine the impact of aBL on β-lactamase activity.
• To assess the synergistic effect of aBL with ceftazidime.

Main Methods:

• Exposure of bacterial strains (P. aeruginosa, E. coli, K. pneumoniae) and purified β-lactamases to aBL (410 nm).
• Assay of β-lactamase activity using chromogenic cephalosporin hydrolysis.
• Analysis of porphyrin photoreaction and protein degradation (SDS-PAGE).
• Evaluation of combined aBL-ceftazidime treatment against a metallo-β-lactamase strain.

Main Results:

• aBL significantly reduced β-lactamase activity in bacteria and purified enzymes.
• A 50% reduction in enzymatic activity was observed in P. aeruginosa after 1.52 J/cm² aBL exposure.
• aBL induced protein degradation, contributing to reduced enzyme activity.
• Combined aBL and ceftazidime enhanced bactericidal effects by over 4-log10 against resistant P. aeruginosa.

Conclusions:

• aBL effectively inhibits bacterial β-lactamase activity.
• aBL presents a potential strategy to combat β-lactam resistance.
• Combination therapy with aBL and antibiotics may overcome antimicrobial resistance.