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

Abstract

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. 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. 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/cm2 , 54 mJ/cm2 or 270 mJ/cm2 ), FAS or both (FAS and UVC at 270 mJ/cm2 ). 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. The lower dosages (13 mJ/cm2 and 54 mJ/cm2 ) of UVC had >90% colony forming unit (CFU) reduction, 270 mJ/cm2 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). 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.