Effect of testing method on apparent activities of antiviral disinfectants and antiseptics.

This study was designed to evaluate the independent effects of various test methods on the activities of antiviral chemical germicides. The activities of germicides against MS2 and phi 6 bacteriophages in a new porcine tissue carrier model were compared to those obtained by four other methods (suspension, glass carrier, tile carrier, and fingerpad tissue carrier tests). After a 1-min contact followed by neutralization (and elution off the carriers), the residual virus in the treated samples was quantified and the amount was compared with that in the saline controls. Antiviral activity was highly dependent on the test method for both viruses and was always greatest in suspension tests and lowest in tissue carrier tests. Results obtained for hydrophilic MS2 with the porcine tissue carrier were comparable to those from fingerpads, but lipophilic phi 6 was subject to spontaneous inactivation on human skin and proved unsuitable for fingerpad testing. These data indicate that the activities of germicides in tests with nonbiological substrates may overestimate antiviral antiseptic activity on skin surfaces. Products intended for use as antiviral antiseptics or hand-washing agents should be evaluated in a tissue carrier system. The porcine tissue carrier model provides a safe, inexpensive, accurate, and reproducible method for testing the activities of antiseptics.