Synergistic bactericidal combinations: far-UV-C, mechanical cleaning and chlorine against Gram-negative and -positive bacteria
DOI:
https://doi.org/10.48797/sl.2024.165Keywords:
PosterAbstract
Background: The issue of indoor contamination stands as a global health challenge, contributing to the spread of infectious diseases [1,2]. Consequently, there is an urgent need to explore new disinfection strategies that rely on reduced concentrations of conventional cleaning chemicals [3,4]. Objective: This study aimed to explore innovative disinfection approaches utilizing far-UV-C (222 nm) radiation along with chlorine and mechanical cleaning, offering a promising solution with minimal application doses. Methods: The study assessed the bactericidal efficacy of far-UV-C (222 nm) at various intensities (78.4 μW/cm2 to 597.7 μW/cm2 for 1 minute) against Escherichia coli and Staphylococcus epidermidis cells adhered to polystyrene microtiter plates by cellular culturability. Furthermore, combinations with mechanical cleaning (ultrasounds for 1 minute) and free chlorine (0.1, 0.5, and 1 mg/L for 5 minutes) were tested. The triple combination of mechanical cleaning + free chlorine (0.5 mg/L) + far-UV-C (54 mJ/cm2) was also evaluated against bacteria adhered to materials commonly found in hospital settings and other public spaces: polyvinyl chloride (PVC), stainless steel (SS), and polyetheretherketone (PEEK). Results: Disinfection with far-UV-C (54 mJ/cm2) and free chlorine at 0.5 mg/L for 5 minutes achieved a complete reduction of culturable E. coli cells and a logarithmic reduction of 2.98 ± 0.03 CFU/cm2 for S. epidermidis. The triple combination resulted in a total reduction of culturable cells for both adhered bacteria. Bacterial adhesion to PVC, SS, and PEEK varied, influencing the bactericidal activity of the triple combination, with logarithmic reductions of up to 3 CFU/cm2. Conclusions: The study underscores the efficiency of far-UV-C (54 mJ/cm2) combined with chlorine (0.5 mg/L; 5 minutes) and mechanical cleaning (1 minute) as an effective disinfection strategy under mild conditions. Utilizing a combination of mechanical and chemical disinfection strategies is recommended to detect regrowth events and enhance the effectiveness of microbial growth control.References
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2. Dhama, K., Patel, S.K., Kumar, R., Masand, R., Rana, J., Yatoo, M.I., et al. The role of disinfectants and sanitizers during COVID-19 pandemic: advantages and deleterious effects on humans and the environment. Environ. Sci. Pollut. Res. Int. 2021 28, 34211–34228.
3. Pereira, A.R., Braga, D.F.O., Vassal, M., Gomes, I.B., Simões, M. Ultraviolet C irradiation: a promising approach for the disinfection of public spaces? Sci. Total Environ. 2023 879, 1–22.
4. Vassal, M., Gomes, I.B., Pereira, A.R., Simões, M., Braga, D.F.O., Teixeira, B. Combination of UVC light with antimicrobial agents for enhanced disinfection of surfaces and liquids. J. Environ. Chem. Eng. 2023 11, 1–22.
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Copyright (c) 2024 Mariana Sousa, Isabel M. Oliveira, Liliana Correia, Inês B. Gomes, Cátia A. Sousa, Daniel F. O. Braga, Manuel Simões
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