Antimicrobial Photodynamic Coatings Reduce the Microbial Burden on Environmental Surfaces in Public Transportation—A Field Study in Buses

Abstract

Millions of people use public transportation daily worldwide and frequently touch surfaces, thereby producing a reservoir of microorganisms on surfaces increasing the risk of transmission. Constant occupation makes sufficient cleaning difficult to achieve. Thus, an autonomous, permanent, antimicrobial coating (AMC) could keep down the microbial burden on such surfaces. A photodynamic AMC was applied to frequently touched surfaces in buses. The microbial burden (colony forming units, cfu) was determined weekly and compared to equivalent surfaces in buses without AMC (references). The microbial burden ranged from 0–209 cfu/cm2 on references and from 0–54 cfu/cm2 on AMC. The means were 13.4 ± 29.6 cfu/cm2 on references and 4.5 ± 8.4 cfu/cm2 on AMC (p < 0.001). The difference in microbial burden on AMC and references was almost constant throughout the study. Considering a hygiene benchmark of 5 cfu/cm2, the data yield an absolute risk reduction of 22.6% and a relative risk reduction of 50.7%. In conclusion, photodynamic AMC kept down the microbial burden, reducing the risk of transmission of microorganisms. AMC permanently and autonomously contributes to hygienic conditions on surfaces in public transportation. Photodynamic AMC therefore are suitable for reducing the microbial load and closing hygiene gaps in public transportation.

Photodynamic Inactivation of Bacteria in Ionic Environments Using the Photosensitizer SAPYR and the Chelator Citrate†

“…The field study was performed in two hospitals for several months and the results of the study clearly proved that the novel photodynamic coating significantly reduced the bacterial burden on patient-near surfaces, which may reduce the risk of nosocomial transmission of pathogens (18). Unfortunately, despite the advantages of PDI coatings and its proven efficacy in field studies (18,(20)(21)(22), the use of silver, copper and quaternary ammoniums are reported to be the major technologies so far, whereas the role of PDI is almost unmentioned (23,24).…”

Microbiota shaping and bioburden monitoring of indoor antimicrobial surfaces

“…In another study, the effect of photodynamic AMC on the microbial burden of frequently touched surfaces in public buses was investigated using the plating method. The results showed that photodynamic AMC kept the microbial load low and significantly reduced the risk of microbial transfer (Kalb et al, 2022). Numerous studies have applied traditional, culture-based microbial surveys, and the results have provided basic information about the microbial burden levels on different surfaces.…”

Long‐term durability of thermoplastic elastomer containing antiviral additives for mobility applications

“…There have been many attempts to provide solutions to this task including antimicrobial coatings, films, or surfaces that can further reduce the spread of the infectious pathogens for prolonged periods of time. [4][5][6][7][8] Chang et al (2019) 9 used natural resin from coniferous pine tree to blend with synthetic polymer (Poly(ε-caprolactone) (PCL)) to take advantage of the highly antimicrobial property of the natural resin and create a more sustainable composite. Authors presented encouraging results suggesting that the new blends at 50% by weight still possess antimicrobial properties against four strains of bacteria (S. aureas, E. coli, B. subtilis, and P. aeruginosa).…”

“…The results showed a 25% reduction in bacteria colony counts. 7 Hardison et al has evaluated the residual efficacy of quaternary ammonium compounds (QACs) against SARS-CoV-2 on stainless steel and on acrylonitrile butadiene styrene (ABS) plastic. Their study demonstrated that some commercial products showed 1.67 to 3-log reductions against SARS-CoV-2.…”