No abstract

The antiviral properties of zeolite (sodium aluminosilicate) powders amended with metal ions were assessed using human coronavirus 229E, feline infectious peritonitis virus (FIPV), and feline calicivirus F-9. Zeolites containing silver and silver/copper caused significant reductions of coronavirus 229E after 1 h in suspension. The silver/copper combination yielded a [5.13-log 10 reduction within 24 h. It was also the most effective ([3.18-log 10 ) against FIPV after 4 h. Other formulations were ineffective against FIPV. On plastic coupons with incorporated silver/ copper-zeolites, [1.7-log 10 and [3.8-log 10 reductions were achieved for coronavirus 229E and feline calicivirus within 24 h, respectively. Silver/copper zeolite reduced titers of all viruses tested, suggesting that it may be effective against related pathogens of interest [i.e., SARS coronavirus, other coronaviruses, human norovirus (calicivirus)]. Of note, it was effective against both enveloped and nonenveloped viruses. Metal-zeolites could therefore possibly be used in applications to reduce virus contamination of fomites and thus the spread of viral diseases.

Contamination events and biofilms can decrease the amount of free chlorine available in drinking water systems. The efficacy of 100 μg/L silver and 400 μg/L copper, individually and combined, were evaluated as secondary, longer-lasting residual disinfectants against Salmonella enterica serovar Typhimurium, Escherichia coli, Listeria monocytogenes, and Mycobacterium fortuitum at 24°C and 4°C. A >5.0-log10 reduction was observed in E. coli and L. monocytogenes after three hours and S. Typhimurium following seven hours of exposure to silver. M. fortuitum was the most resistant species to silver (1.11-log10 after seven hours). Copper did not significantly reduce S. Typhimurium and E. coli at 24°C; ≥2.80-log10 reductions were observed in the Gram-positive L. monocytogenes and M. fortuitum. Longer exposure times were required at 4°C to achieve significant reductions in all species. A synergistic effect was observed when silver and copper were combined at 24°C. In addition, silver was not affected by the presence of organic matter at concentrations that completely inhibited 0.2 mg/L chlorine. The results of this study suggest that combinations of silver and copper show promise as secondary residual disinfectants. They may also be used in conjunction with low chlorine levels or other disinfectants to provide additional, long-lasting residuals in distribution systems.