Performance evaluation of antimicrobial blue light for inactivating multidrug-resistant bacteria on common fabric materials

Hanlin Liu; Huihui Zhang; Alvin C K Lai

doi:10.1016/j.jiph.2025.102846

Performance evaluation of antimicrobial blue light for inactivating multidrug-resistant bacteria on common fabric materials

J Infect Public Health. 2025 May 28;18(10):102846. doi: 10.1016/j.jiph.2025.102846. Online ahead of print.

Authors

Hanlin Liu¹, Huihui Zhang¹, Alvin C K Lai²

Affiliations

¹ Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong.
² Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong. Electronic address: alvinlai@cityu.edu.hk.

PMID: 40616911
DOI: 10.1016/j.jiph.2025.102846

Abstract

Background: Fomite transmission of multidrug-resistant bacteria in hospitals is a serious public health issue. Antimicrobial blue light (aBL) holds great promise in reducing the incidence of healthcare-associated infections (HAIs) while being safe for use.

Methods: This study evaluated the influence of surface materials on the bactericidal performance of aBL against three multidrug-resistant bacteria: Methicillin-resistant Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Six microbial-contaminated surfaces were studied: glass, cotton, towel, blanket, sofa and bedsheet.

Results: At the same dose of 3.3 J/cm², aBL treatment for bedsheets resulted in a 3.0 times higher log reduction in colony forming counts (CFUs) than sofa material. This significant difference may be partly due to fabric porosity and variations in light penetration. Additionally, a positive linear relationship between reactive oxygen species (ROS) generation and microbial reduction was established, indicating that higher intracellular ROS levels corresponded linearly to more effective bactericidal performance by aBL. We also systematically compared the penetration and bactericidal performance of aBL with 254 nm Ultraviolet C (UVC) and 222 nm Far-UVC for testing double-layer cotton samples. Both UVC and Far-UVC outperformed aBL treatment for single-layer fabrics. Nonetheless, due to the very low light penetration of shorter wavelengths, the bactericidal efficiency of UVC and Far-UVC was substantially reduced for the bottom-layer sample. For aBL, the difference in bactericidal efficiency data between top-layer and bottom-layer was approximately 10 %.

Conclusion: aBL exhibited varying bactericidal efficacy across different surfaces, with the highest microbial reduction observed on bedsheet and the lowest reduction on sofa fabric. Furthermore, aBL demonstrated superior bactericidal performance against drug-resistant bacteria on multi-layer fabrics compared to Far-UVC and UVC.

Keywords: Healthcare-associated infections; Multidrug-resistant bacteria; Porous and nonporous materials; Reactive oxygen species; Surface decontamination.