Efficacy of commonly used disinfectants for the inactivation of calicivirus on strawberry, lettuce, and a food-contact surface

Norwalk and Norwalk-like viruses (NLVs) are important causes of foodborne g astroenteritis in restaurant-related outbreaks. Efficacy of common disinfec tion methods against these viruses on food-contact surfaces and fresh produ ce is not known partially because of their nonculturability. Seven commerci al disinfectants for food-contact surfaces and three sanitizers for fruits and vegetables were tested against cultivable feline calicivirus (FCV). Dis ks of stainless steel, strawberry, and lettuce were contaminated with known amounts of FCV. The disinfectants were applied at one, two, and four times the manufacturer's recommended concentrations for contact times of 1 and 1 0 min. The action of disinfectant was stopped by dilution, and the number o f surviving FCVs was determined by titration in cell cultures. An agent was considered effective if it reduced the virus titer by at least 3 log(10) f rom an initial level of 10(7) 50% tissue culture infective dose. None of th e disinfectants was effective when used at the manufacturer's recommended c oncentration for 10 min. Phenolic compounds, when used at two to four times the recommended concentration, completely inactivated FCV on contact surfa ces. A combination of quaternary ammonium compound and sodium carbonate was effective on contact surfaces at twice the recommended concentration. Rins ing of produce with water alone reduced virus titer by 2 log(10). On artifi cially contaminated strawberry and lettuce, peroxyacetic acid and hydrogen peroxide was the only effective formulation when used at four times the man ufacturers' recommended concentration for 10 min. These findings suggest th at FCV and perhaps NLVs are very resistant to commercial disinfectants, How ever. phenolic compounds at two to four times their recommended concentrati ons appear to be effective at decontaminating environmental surfaces and ma y help control foodborne outbreaks of calicivirus in restaurants.