Evaluation of the mPaleTM antimicrobial surface coating for decontamination of environmental surfaces in hospital rooms

Background: Environmental surfaces may play an important role in transmission of healthcare-associated pathogens, including Clostridium difficile, methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE). Because colonized patients may continually shed pathogenic organisms, an ideal environmental cleaning product would provide continuous disinfection of surfaces. mPale^TM is an EPA-registered antimicrobial (3-trimethoxy silyl propyl dimethyl octadecyl ammonium chloride) that is designed to adhere to environmental surfaces to provide continuous and long-lasting decontamination. 

Objective: To test the hypothesis that application of mPale results in persistent antimicrobial activity on commonly-touched environmental surfaces in hospitals. 

Methods: In the laboratory, MRSA, VRE, and C. difficile spores were repeatedly inoculated onto surfaces for 1 month and the numbers of organisms recovered was compared for mPale-treated versus untreated control surfaces. In hospital rooms, total bacterial counts were compared for mPale-treated versus untreated control surfaces (e.g., call buttons, charts, telephones, and portable computers) for 1-month after application of the antimicrobial coating.  

Results: On laboratory surfaces that were not cleaned, coating with mPale was effective in reducing recovery of repeated inoculums of MRSA or VRE by ≥2-3 logs for a 1-month period (P <0.001), but there was no reduction in C. difficile spores. However, when the same surfaces were cleaned with 10% bleach or with sterile water, the efficacy of mPale was lost within 3 days. In hospital rooms, total bacterial counts recovered from commonly-touched surfaces were significantly reduced for 3-6 days, but after 9 days there was no difference between mPale-treated and untreated control surfaces (P =1).  

Conclusions: mPale antimicrobial coating was effective in reducing recovery of MRSA and VRE from inoculated surfaces in a laboratory setting.  However, the efficacy was lost within days when mPale-coated surfaces were subjected to cleaning with water or bleach and a similar loss of efficacy was observed for mPale-coated surfaces in hospital rooms. In contrast to the manufacturer's claims, our findings suggest that mPale antimicrobial coating is easily removed by washing with bleach solution or water.