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

Abstract

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 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 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.Evaluating the antiviral activities of topical antiseptics is a critical step toward preventing infections spread through or by the skin. However, the Food and Drug Administration has not achieved a consensus about the best methods for such evaluations, and standards for demonstrating antiseptic efficacy against viruses have not been promulgated. Data from test methods used to evaluate the activities of surface disinfectants are often cited as evidence supporting the efficacy of topical antiseptics (4). These methods do not model the complex organic milieu of skin, and their reliability in predicting antiviral antiseptic activity has been questioned (2,6,8,20).We have tested a new model of antiviral antisepsis that utilizes a tissue carrier but circumvents the biohazard exposure risk to human subjects. This model employs ex vivo pigskin, the animal tissue which closely resembles the structure and function of human skin (14), to evaluate antiseptic activity. To evaluate the utility of the porcine model, the effect of the carrier material on antiviral activity was assessed in suspension, glass slide, ceramic tile, and fingerpad carrier tests conducted in parallel with the porcine carrier test. Two bacteriophages, MS2 (a nonenveloped virus known to be relatively resistant to disinfection) (9) and 6 (an enveloped virus known to be more susceptible to common germicides) (23), were used as surrogates for human pathogens in these studies. MATERIALS AND METHODSTest organisms. Escherichia coli Hfr3000 (ATCC 15597) was maintained in MS medium (7) and used as the host for the MS2 bacteriophage (ATCC 15597-B1). A high-titer stock of MS2 bacteriophage was made by pipetting 5 ml of...

Development of a Test System To Apply Virus-Containing Particles to Filtering Facepiece Respirators for the Evaluation of Decontamination Procedures

“…Carrier tests, which are commonly performed by dipping or spiking the viral challenge onto the substrate, do not account for the physical characteristics of aerosols, such as particle size, composition, velocity, desiccation, and subsequent substrate penetration (8,21,30). It has been shown previously that the testing method has an effect on the activities of disinfectants (9,24,38). Woolwine and Gerberding showed that inactivation of FIG.…”

“…The virus suspension (10 11 PFU/ml) was stored at 4°C in 50-ml conical tubes (Falcon, Becton Dickinson) for use in experiments. MS2 was selected for the study based on its moderate resistance to disinfectants, survivability, ease of preparation and assay, and nonpathogenicity (18,38).…”

Real-Time Fluorogenic Reverse Transcription-PCR Assays for Detection of Bacteriophage MS2

“…MS2 has been used in place of pathogens in a large number of studies: for examining the survival of viruses on produce (1,11), developing systems and methods to remove viruses from water and surfaces (5, 9, 10, 12, 13, 17-20, 23-25, 29, 30, 32-34, 42), and investigating the fate of pathogens in groundwater (2,14,15,26,31,(36)(37)(38)(39). It has also been used in the testing and development of systems for the detection of biological warfare agents (3,8,22,35,40,41).…”

Hand Hygiene

“…For example, determination of the minimum inhibitory concentration (MIC) of such formulations against bacteria has no direct bearing on the "killing effect" expected of such products in the field. Conditions in suspension and in vitro 192 or ex vivo 193 testing do not reflect those on human skin. Even simulated-use tests with subjects are considered by some as "too controlled", prompting testing under in praxi or field conditions.…”

“…297 Other enveloped viruses that are somewhat less susceptible, but are killed by 60-70% alcohol, include hepatitis B virus (HBV) and probably hepatitis C virus. 298 In a porcine tissue carrier model used to study antiseptic activity, 70% ethanol and 70% isopropanol were found to reduce titres of an enveloped bacteriophage more effectively than an antimicrobial soap containing 4% CHG. 192 Numerous studies have documented the in vivo antimicrobial activity of alcohols. Early quantitative studies of the effects of antiseptic handrubs established that alcohols effectively reduce bacterial counts on hands.…”