Disinfection of fabrics and carpets artificially contaminated with calicivirus: relevance in institutional and healthcare centres.

Fabrics and carpets are used widely as surface coverings or linens in healthcare settings and are prone to contamination with infectious agents such as noroviruses (NoVs). Laundering, water cleaning and vacuuming are considered to be adequate for routine cleaning of these materials, but no standard procedure for their disinfection is available in case of contamination. Testing disinfectants for their efficacy against NoVs is difficult because these viruses cannot be cultivated in vitro. Therefore, feline calicivirus (FCV) has gained acceptance as a surrogate model for NoVs in disinfectant efficacy testing. The present study evaluated five disinfectants against FCV on various fabrics or carpets. FCV was dried on fabrics and carpets, followed by treatment with a given disinfectant for a defined contact time of 1, 5 or 10 min. The surviving virus was then eluted and titrated in Crandell-Reese feline kidney cells to determine virus inactivation. A disinfectant was considered to be effective if it inactivated at least 99% of the applied virus. Metricide, an activated dialdehyde-based product, was found to be the most effective disinfectant on all types of fabric and carpet, inactivating more than 99.99% of the virus in 1-10 min. In general, effectiveness of disinfectants increased with an increase in exposure time from 1 to 10 min. The disinfection of carpets was more difficult than the disinfection of fabrics; 100% polyester was the least amenable to disinfection. Only Metricide and Microbac-II (a phenolic compound) were able to inactivate 99% of FCV on 100% polyester. In summary, activated dialdehyde was found to be uniformly active against FCV on all types of material tested.

Evaluation of a rapid readout biological indicator for 121 degrees C gravity and 132 degrees C vacuum-assisted steam sterilization cycles.

OBJECTIVE: A biological indicator (BI), based on fluorescent detection of a spore-associated enzyme, has been developed. We evaluated the new BI against five conventional self-contained BIs in a 121 degrees C gravity-displacement sterilizer and, packaged in towel packs and disposable steam test packs, in a 132 degrees C vacuum-assisted sterilizer. DESIGN: In the 121 degrees C gravity-displacement sterilizer, rapid readout BIs and conventional BIs were tested together in an otherwise empty chamber. Exposure times were 5, 10, and 15 minutes. In the 132 degrees C vacuum-assisted steam sterilizer, BIs were contained in towel packs or disposable steam test packs. Surgical packs were added to represent a full load. Exposure times were 0, 1, and 2 minutes. RESULTS: In gravity-displacement 5-minute cycles, the rapid readout BIs yielded 100% positive results within 30 minutes. The conventional BIs ranged from 72% to 100% positive in 48 hours. At 10 minutes, the rapid readout BIs were 83% positive after 3 hours, whereas the conventional BIs ranged from 0% to 37% positive after 48 hours. All indicators were negative after 15-minute exposures. In vacuum-assisted cycles, all indicators were negative after 3 minutes. After 1-minute exposures, the rapid readout BIs were 40% to 60% positive, whereas the conventional BIs were 15% to 20% positive. CONCLUSION: The rapid readout BIs are a more sensitive indicator of marginal steam sterilization cycles than conventional self-contained BIs. They yield results within 3 hours, as compared to 24 to 48 hours for the conventional BIs.

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 gastroenteritis in restaurant-related outbreaks. Efficacy of common disinfection methods against these viruses on food-contact surfaces and fresh produce is not known partially because of their nonculturability. Seven commercial disinfectants for food-contact surfaces and three sanitizers for fruits and vegetables were tested against cultivable feline calicivirus (FCV). Disks 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 10 min. The action of disinfectant was stopped by dilution, and the number of surviving FCVs was determined by titration in cell cultures. An agent was considered effective if it reduced the virus titer by at least 3 log10 from an initial level of 10(7) 50% tissue culture infective dose. None of the disinfectants was effective when used at the manufacturer's recommended concentration for 10 min. Phenolic compounds, when used at two to four times the recommended concentration, completely inactivated FCV on contact surfaces. A combination of quaternary ammonium compound and sodium carbonate was effective on contact surfaces at twice the recommended concentration. Rinsing of produce with water alone reduced virus titer by 2 log10. On artificially contaminated strawberry and lettuce, peroxyacetic acid and hydrogen peroxide was the only effective formulation when used at four times the manufacturers' recommended concentration for 10 min. These findings suggest that FCV and perhaps NLVs are very resistant to commercial disinfectants. However, phenolic compounds at two to four times their recommended concentrations appear to be effective at decontaminating environmental surfaces and may help control foodborne outbreaks of calicivirus in restaurants.