Evaluation of phototherapeutic antibacterial activity of LED-illuminated curcumin nanomicelles against multidrug-resistant K. pneumoniae harbouring extended-spectrum β-Lactamase (ESBL) and carbapenemase resistance genes.

Abstract

This study evaluated the antibacterial effect of photodynamic therapy (aPDT) using nanomicelle-encapsulated curcumin photosensitizer (PS) against drug-resistant clinical isolates of Klebsiella pneumoniae and K. pneumoniae ATCC 13883^™. In this study, nanomicelle curcumin prepared by the thin film hydration method, with LED as the radiation source, was used for effective aPDT. The technique's effectiveness was analysed through membrane changes tracked by flow cytometry, bacterial structural alterations observed via FTIR, lipid peroxidation quantification assay, atomic force microscopy, and its performance against 17 clinical isolates resistant to cephalosporins and carbapenems was evaluated. Based on the results of aPDT, the minimum inhibitory concentration of the PS was 200 μg/mL for the standard strain and 125-1000 μg/mL for superbug clinical isolates. With an irradiation dose of 500 J/cm², an irradiation time of 500 s, and a power density of 1000 mW/cm² from an LED, bacterial growth was inhibited by a mean of 8 Log10 CFU/mL reduction, as determined by the culture method. Additionally, the results of the bacterial structural integrity assays (flow cytometry, FTIR, MDA levels, and AFM) for the standard strain provided convergent evidence with the culture results. This study demonstrates antibacterial activity of LED-illuminated curcumin nanomicelles against multidrug-resistant K. pneumoniae.