Qualification of the Disinfection Efficacy of an Ultraviolet Autonomous Robot for Use in Pharmaceutical Clean Rooms.

The aim of this study was to evaluate the efficacy of a UV-C disinfection robot intended for use on various cleanroom surfaces in the manufacturing facilities at AstraZeneca against a panel of different microorganisms. The studies performed used a method based on the Surface Challenge Test Method EN 13697² to evaluate the reduction in microbial viability after an inoculated surface was exposed to a with a light source emitting 254nm UV-C energy. In this surface challenge test, representative microorganisms were seeded onto coupons representing typical surfaces found in the cleanroom manufacturing areas. The inoculated coupons were treated with the UV-C light source at multiple dose-levels (mJ/cm²) to generate a death curve per organism, representing the required dose to achieve the desired log reduction as per USP<1072>¹¹ for disinfectant efficacy. The UV-C light source was tested against a panel of five American Type Culture Collection (ATCC) organisms (Pseudomonas paraeruginosa, Staphylococcus aureus, Bacillus spizizenii, Candida albicans and Aspergillus brasiliensis) and environmental isolates (Micrococcus luteus, Moraxella osloensis, Bacillus Cereus & Penicillium chrysogenum) selected from major AstraZeneca sites, which included those likely to present the greatest challenge to the effectiveness of the UV-C. The robot was qualified and shown to be suitable for use and can achieve a 3-log reduction for bacteria and 2-log reduction for spores depending on the dose applied. The dose selected by AstraZeneca was 100 mJ/cm² which represented the most practicable dose for the majority of clean room isolates with a higher dose reserved for use if adverse events for moulds or bacterial spores were recovered.