Is the combination of UV-C light and bleach less effective than bleach alone for intensive care unit surface disinfection?

Background

Chlorine-based disinfectants, such as bleach, are commonly used for cleaning in healthcare settings to prevent the transmission of nosocomial pathogens. To enhance the efficacy of disinfection, ultraviolet-C (UV-C) light systems have been proposed to supplement standard cleaning procedures. As bleach decomposes in UV light, we hypothesised that the use of UV-C light as an adjunct to manual cleaning with bleach, may decrease the efficacy of disinfection instead.

Methods

In the laboratory, stainless steel sheets and plastic keyboards were inoculated with Pseudomonas aeruginosa (∼10⁶ CFU/ml) and subjected to treatment with either UV-C light only, bleach only or a combination of UV-C light and bleach. The residual bioburden (CFU/ml) was quantified through conventional microbiological techniques. Results were compared to non-exposed control surfaces and against each treatment strategy.

Results

On tested surfaces, there were statistically significant reductions in P. aeruginosa when surfaces were treated with UV-C light only (>2.5 log₁₀ reduction), bleach only (>5.6 log₁₀ reduction) and a combination of UV-C light and bleach (>6.3 log₁₀ reduction) compared to positive control (P < 0.001, all treatment strategies). No significant differences were observed when surfaces were treated with the addition of UV-C light to bleach compared to treatment with bleach alone.

Conclusion

There was no difference in the efficacy of disinfection against P. aeruginosa with the combined treatment strategy of UV-C light and bleach compared to bleach alone under laboratory conditions. Further studies are warranted to elucidate the effectiveness of this technology on other healthcare-associated pathogens.