The article “Biofilms and antimicrobial resistance in healthcare: evaluating chlorine dioxide as a candidate to protect patient safety” by P. Norville, S. Dangleben, and S. Hardy, published in the Journal of Hospital Infection in 2025, addresses the critical challenges of Healthcare-Associated Infections (HAIs) and Antimicrobial Resistance (AMR) within healthcare settings. AMR is identified as a significant public health threat, projected to be directly responsible for 10 million deaths annually by 2050. HAIs, often caused by the transmission of multidrug-resistant organisms (MDROs) from contaminated surfaces, lead to poorer patient outcomes and increased treatment costs.
A growing concern exacerbating the AMR crisis is the formation of biofilms on surfaces and medical devices. Biofilms are structured communities of microorganisms that adhere to a surface and are embedded within a self-produced matrix known as extracellular polysaccharide substance (EPS). This structure significantly reduces the penetration of antimicrobials and contains persister cells, making biofilms less susceptible to standard antimicrobial treatments. Furthermore, biofilms act as reservoirs for MDROs and facilitate the transfer of AMR genes. It is estimated that 65% of all microbial infections and 80% of chronic infections are associated with biofilm formation.
Given the limitations in developing new antimicrobials, the prevention of infections through effective infection prevention and control (IPC) practices is paramount. The study investigates chlorine dioxide, a broad-spectrum oxidizing agent known for its effectiveness against bacteria (including spores), mycobacteria, viruses, and fungi, as a candidate for environmental decontamination. Unlike traditional chlorine-releasing agents, chlorine dioxide does not tend to react with organic materials to form chlorinated species, enhancing its killing ability.
The research evaluated the performance of various chlorine dioxide-based disinfectants against a panel of clinically relevant MDROs and biofilms formed by Pseudomonas aeruginosa and Staphylococcus aureus. The methodology involved a combination of EN standards (such as EN 14885, which covers bactericidal, yeasticidal, fungicidal, virucidal, and sporicidal claims) and the Minimum Biofilm Eradication Concentration (MBEC) assay (ASTM E2799).
The findings of the study demonstrate that all tested chlorine dioxide-based disinfectants exhibited sufficient activity against MDROs, meeting the relevant test standards. Importantly, they also showed similar log10 reductions against organisms within the biofilm model. Specifically, the disinfectants consistently achieved >99.99% (4 log10) reductions against both P. aeruginosa and S. aureus biofilms, with greater reductions observed against P. aeruginosa. This efficacy was achieved at much lower concentrations (120-200 ppm) compared to the 10,000 ppm chlorine used as a positive control. The study concludes that chlorine dioxide is an attractive candidate for environmental decontamination strategies due to its proven efficacy against both planktonic MDROs and biofilms in realistic contact times and at practical concentrations. This highlights its potential to significantly contribute to infection prevention and control efforts, thereby reducing the incidence of HAIs and mitigating the spread of AMR.
Reference: Norville, P., Dangleben, S., & Hardy, S. (2025). Biofilms and antimicrobial resistance in healthcare: evaluating chlorine dioxide as a candidate to protect patient safety. Journal of Hospital Infection, 162, 121-126. https://doi.org/10.1016/j.jhin.2025.04.034
