In-vitro and in-use efficacy of a rapid, targeted UVC decontamination system

Ultraviolet C (UVC) decontamination systems are used in healthcare to supplement manual cleaning. Systems typically target whole rooms with fixed, vertical bulbs.

To evaluate the in-vitro and in-use efficacy of the novel device with emitters on articulating arms designed for rapid, targeted decontamination in a hospital room.

Isolates of meticillin-resistant Staphylococcus aureus (MRSA) (∼10⁶ colony-forming units (cfu)), Klebsiella pneumoniae (∼10⁶ cfu) and Clostridioides difficile spores (∼10⁵ cfu) were inoculated on to stainless steel biological indicators (BIs) with low (0.3% BSA) and high (10% BSA/synthetic faeces) soiling. Bacteria were recovered from BIs following UVC decontamination, enumerated, and compared with controls. In-use efficacy was assessed by sampling aerobic colony counts (ACC) with contact plates. Sites were further sampled for C. difficile. Samples were taken before cleaning, after manual cleaning, and after UVC decontamination.

Reductions of 2.97-4.87 and 0.53-3.63 log₁₀ cfu were demonstrated with MRSA and K. pneumoniae with low and high soiling, respectively. Efficacy against C. difficile was only observed in one location (1.12 log₁₀) with low soiling, but not synthetic faeces. ACC were highest on the bed foot rail (75 cfu/25 cm²) and toilet flush (67 cfu/25 cm²). Bacteria persisted on 50% of surfaces after manual cleaning and 30% after UVC decontamination. C. difficile persisted on one surface.

The system was effective for targeted disinfection and may be used for high-touch surfaces and equipment. The short cycle times allow operation in areas with minimal turnaround time such as operating theatres and anaesthetic rooms.