UV-C light-based surface disinfection: Analysis of its virucidal efficacy using a bacteriophage model

Introduction Reprocessing of medical devices becomes increasingly complex, due to higher hygiene requirements. Former studies revealed satisfactory bactericidal properties of UV-C light disinfection in otorhinolaryngological endoscopes. Especially in the context of the current COVID-19 pandemic, virucidal properties are of high importance. In this study the virucidal efficacy of UV-C light disinfection was analyzed using a bacteriophage model.

Materials and methods MS-2 bacteriophages were used as surrogate for stable viruses with high tenacity. The bacteriophage samples were irradiated for up to three cycles of 25 seconds by UV-C light (D25, UV-Smart Technologies B.V.). A dilution series of the irradiated test samples was mixed with 1×10⁸  CFU of Escherichia coli. After incubation plaque formation of Escherichia coli were counted and hence the phage concentration was determined.

Results The initial contamination of the test samples was 1.8×10¹²+ plaque forming units (pfu). After 25 seconds of UV-C light irradiation, a non-significant Log reduction of 2.2 was found (p=0,82). After 50 and 75 seconds of UV-exposure a significant Log reduction of 3.4 e.g. 5.1 (p=0.05 e.g. p=0.004) was found. The control sample showed a titer of 1.2 × 10¹⁰ pfu.

Conclusion The tested UV system seems to provide a significant virucidal effect after a short time of exposure. In combination with the results of the bacteriological testing it appears suitable for clinical use as a substitute for current disinfection methods.

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Artikel online veröffentlicht:
24. Mai 2022