Virucidal efficacy of antimicrobial surface coatings against the enveloped bacteriophage Φ6.

AIMS: Antimicrobial coatings, for use in combination with routine cleaning and disinfection, were evaluated for their effectiveness in reducing virus concentration on stainless steel surfaces. METHODS: Twenty antimicrobial coating products, predominantly composed of organosilane quaternary ammonium compounds, were applied to stainless steel coupons, dried overnight and evaluated for efficacy against Φ6, an enveloped bacteriophage. Additionally, two peel and stick polymer-based films, a copper-based film and three copper alloys were evaluated. Efficacy was determined by comparison of recoveries from uncoated (positive control) and coated (test) surfaces. RESULTS: The results indicated that some of the coating products initially demonstrated >3-log reduction of Φ6; no direct correlation of efficacy was observed with an active ingredient or its concentration. The peel and stick films and copper alloys each demonstrated efficacy in initial testing. However, none of the spray-based products retained efficacy after subjecting the coating to abrasion with either a hypochlorite or quaternary ammonium-based solution applied in accordance with EPA Interim Guidance for Evaluating the Efficacy of Antimicrobial Surface Coatings. Of the products tested for this durability, only one peel and stick polymeric film retained efficacy; the copper alloys were not tested for their durability in this study. CONCLUSIONS: These results suggest that while some organosilane quaternary ammonium compound-based products demonstrate antiviral efficacy, more research and development is needed to understand effective formulations with sufficient durability to perform as supplements to routine cleaning and disinfection.

Decontamination of soil contaminated at the surface with Bacillus anthracis spores using dry thermal treatment.

In the event of a large, aerosol release of Bacillus anthracis spores in a major metropolitan area, soils and other outdoor materials may become contaminated with the biological agent. A study was conducted to assess the in-situ remediation of soil using a dry thermal treatment approach to inactivate a B. anthracis spore surrogate inoculated into soil samples. The study was conducted in two phases, using loam, clay and sand-based soils, as well as biological indicators and spore-inoculated stainless-steel coupons. Initial experiments were performed in an environmental test chamber with temperatures controlled between 80 and 110 °C, with and without added humidity, and with contact times ranging from 4 h to 7 weeks. Tests were then scaled up to assess the thermal inactivation of spores in small soil columns, in which a heating plate set to 141 °C was applied to the soil surface. These column tests were conducted to assess time requirements to inactivate spores as a function of soil depth and soil type. Results from the initial phase of testing showed that increasing the temperature and relative humidity reduced the time requirements to achieve samples in which no surrogate spores were detected. For the test at 80 °C with no added humidity, 49 days were required to achieve soil samples with no spores detected in clay and loam. At 110 °C, 24 h were required to achieve samples in which no spores were detected. In the column tests, no spores were detected at the 2.5 cm depth at four days and at the 5.1 cm depth at 21 days, for two of the three soils. The experiments described in the study demonstrate the feasibility of using dry thermal techniques to decontaminate soils that have been surficially contaminated with B. anthracis spores.