Can ultraviolet light C decrease the environmental burden of antimicrobial-resistant and -sensitive bacteria on textiles?

Background: The environment is important in transmission of bacteria. Textiles are difficult and time consuming to clean; ultraviolet light C (UVC) is germicidal and may be an effective disinfection method for textile surfaces.

Objective: This study evaluated the efficacy of UVC, a commercial quaternary ammonium compound antimicrobial spray (FAS) and UVC+FAS combined for reducing bacterial colonization on experimentally contaminated textiles.

Methods: Microfibre, cotton and polyester were inoculated with meticillin-sensitive and -resistant Staphylococcus aureus (MSSA and MRSA), Staphylococcus pseudintermedius (MSSP and MRSP), Pseudomonas aeruginosa or Escherichia coli. ATCC strains were used except for MRSP, for which ten canine clinical isolates were collected. Textiles were treated with three doses of UVC (13 mJ/cm , 54 mJ/cm or 270 mJ/cm ), FAS or both (FAS and UVC at 270 mJ/cm ). UVC was delivered using a modified mercury-based lamp. Bleach (8.25%) was used as a positive control. Negative controls received no treatment. Surface bacterial counts were determined 24 h post-treatment.

Results: The lower dosages (13 mJ/cm and 54 mJ/cm ) of UVC had >90% colony forming unit (CFU) reduction, 270 mJ/cm had >99% CFU reduction and combined UVC+FAS had 100% CFU reduction against all bacterial strains on all surfaces (P < 0.05). Ten experiments showed that treatment with UVC had a greater CFU reduction when compared to FAS alone (P < 0.05). A majority of those experiments (seven of 10) involved Gram-negative species (P. aeruginosa or E. coli).

Conclusion: UVC quickly reduced the bacterial burden on textiles to greater than 90%; UVC may be a better disinfecting agent than FAS for Gram-negative species.