Inside-out Ultraviolet-C Sterilization of Pseudomonas aeruginosa Biofilm In Vitro

Biofilms are difficult to eradicate due to a protective architecture and create major challenges in patient care by diminishing both host immune response and therapeutic approaches. This study investigated a new strategy for treating surface-attached biofilms by delivering germicidal UV through a material surface in a process referred to as “inside-out sterilization” (IOS). Mature Pseudomonas aeruginosa (ATCC^® 27853^™) biofilms were irradiated with up to 1400 mJ cm⁻² of germicidal UV from both ambient and IOS configurations. The lethal dose for the ambient exposure group was 461 mJ cm⁻² 95% CI [292, 728] compared to the IOS treatment group of 247 mJ cm⁻² 95% CI [187, 325], corresponding to 47% less UV dosage for the IOS group (P < 0.05). This study demonstrated that with IOS, a lower quantal dosage of UV energy is required to eradicate biofilm than with ambient exposure by leveraging the organizational structure of the biofilm.