Enhanced Effect of Patient Room Disinfection Against Carbapenem-Resistant Enterobacter cloacae and Methicillin-Resistant Staphylococcus aureus Using UV-C Irradiation in Conjunction with UV-C Containment Unit

Abstract

Background/Objectives: In environments with high-frequency contact surfaces, drug-resistant bacteria, such as carbapenem-resistant Enterobacterales and methicillin-resistant Staphylococcus aureus (MRSA), can survive for extended periods, contributing to healthcare-associated infections. Ultraviolet (UV)-C irradiation often fails to adequately disinfect shadowed areas, leading to a persistent contamination risk. We evaluated the effectiveness of using a UV-C containment unit (UVCCU) in conjunction with UV-C irradiation to improve the sterilization effects on both direct and indirect surfaces, including shadowed areas, and to assess the leakage of UV radiation to the surroundings. Methods: In a model patient room, agar media inoculated with carbapenem-resistant Enterobacter cloacae and MRSA were placed at multiple locations on direct and indirect surfaces around the bed. We used the UV-C irradiation system, UVDI-360, to irradiate the bedroom-environment surfaces with and without a UVCCU. The reduction in bacterial colony counts with and without the UVCCU was measured by counting colony-forming units and calculating the log reduction values, and the UV radiation leakage outside the UVCCU was measured. Results: The use of the UVCCU led to a significant reduction in MRSA colony counts, even in shadowed areas that had previously been inadequately disinfected (with the UVCCU: 2.7 [2.7-2.8]; without the UVCCU: 0.6 [0.5-0.7]; p < 0.01). Additionally, the use of the UVCCU kept the UV radiation leakage to the surrounding environment within regulated limits. Conclusions: These findings suggest that a UVCCU can enhance the disinfection efficacy for multidrug-resistant organisms on healthcare environmental surfaces. The portability and ease of use of the UVCCU indicate its promise as an auxiliary device for UV-C disinfection in healthcare settings.

Keywords: UV-C containment unit; carbapenem-resistant Enterobacter cloacae; environmental transmission; methicillin-resistant Staphylococcus aureus; ultraviolet-C.

Figure 1

The bed unit and shielding system UVCCU. (a) A bed unit that mimics an actual hospital room is created in one bed of the model hospital room (4-bed room); (b) a shielding system UV-C containment unit is installed to surround the bed unit. UV, ultraviolet; UVCCU, UV-C containment unit.

Figure 2

The locations for placing agar media and the position of the UVDI-360 within the bed unit. Agar media coated with carbapenem-resistant Enterobacter cloacae and methicillin-resistant Staphylococcus aureus were placed at seven locations, including surfaces directly hit by UV-C and indirect surfaces that were shaded. The distances from the UVDI-360 installed on the right and left sides of the bed to each directly irradiated surface were as follows: head position of the bed, right (171 cm), left (173 cm); overbed table (tabletop), right (105 cm), left (107 cm); bedside cabinet (tabletop), right (123 cm), left (216 cm); bed rails, right (61 cm), left (142 cm); curtain (pole part), right (87 cm), left (226 cm). On the other hand, the distances from the UVDI-360 installed on the right and left sides of the bed to each indirectly irradiated surface were as follows: footboard (outer side), right 92 cm, left 94 cm; bedside cabinet (left side), right (126 cm), left (232 cm). The UVDI-360 was irradiated at position A for 5 min and then at position B for 5 min, considering this as one cycle, and a total of three cycles were conducted. UV, ultraviolet.

Figure 3

The positional relationship and irradiation method of the UVDI-360 within the bed unit. The UVDI-360 was installed at two locations, designated as points A and B. The UVDI-360 was irradiated at position A for 5 min and then at position B for 5 min, considering this as one cycle, and a total of three cycles were conducted.