Airborne disinfection is an efficient disinfecting method for various surfaces to inactivate bacteria, fungi and spores [1, 14]. However, the efficiency of airborne disinfection against viruses was not extensively reported. Therefore we decided to take advantage of procedures described in a norm [3] recommended for testing airborne disinfection against microbes (bacteria, fungi and spores) to evaluate the virucidal effect of disinfectants diffused by hot fogging on poliovirus type 1, a non enveloped virus which is resistant to disinfectants in suspension.
The virucidal activity of peracetic acid (PAA) on enveloped and non-enveloped viruses (duck hepatitis B virus, vaccinia virus, adenovirus type 2, poliovirus type 1) in suspension, and on adenovirus or murine norovirus on stainless steel carrier was reported [15, 16]. For the first time, the present work demonstrates, that airborne peracetic acid-based disinfectants can inactivate dried poliovirus inocula on stainless steel carrier as well.
Our data obtained in conditions of humidity and temperature similar to those that were previously recommended or reported [3, 9], are in agreement with those of other groups who recently reported that vapours of hydrogen peroxide, which together with peracetic acid are peroxygen, had virucidal activity on various viruses, especially poliovirus [8, 9]. The advantage of peracetic acid is that its biocidal effect, higher than the one of hydrogen peroxide, is obtained at low concentrations even in presence of soils (organic or inorganic) [17].
Peracetic acid is a broad-spectrum disinfectant that showed a virucide activity on enveloped and non-enveloped viruses [16, 18, 19]. The activity of peracetic acid is similar to the peroxygen, it denatures proteins and enzymes and increases the permeability of membranes by disrupting sulfhydryl and sulphur bonds [15]. It is an oxiding agent that has probably direct effects on viral proteins and RNA and indirect effects through the production of hydroxyl radicals and other short-lived products [20].
In a hospital environment, stainless steel is used for door handles, hand and grab rails in toilets. Therefore stainless steel discs, which were used in this study, were relevant to test the efficiency of disinfectants on surfaces. Furthermore these discs do not bind, absorb or sequester viruses and are small enough to be easily handled, as it was previously described [7].
When virus preparations were exposed to peracetic acid, the recovered samples were cytotoxic due to the presence of biocide, which impaired the measurement of virus titers. Therefore, the elimination of disinfectants from the recovered samples is critical before testing the level of infectious viral particles in recovered samples. Gel filtration columns enabled us to remove the disinfectants and therefore the cytotoxicity of samples without affecting the titer of poliovirus. This is in agreement with results of previous studies that demonstrated the efficiency of such a methodology for this purpose when disinfectant products were tested against viruses in suspension and on surfaces [9, 21, 22].
In this study, flocked swabs were used to recover viruses on stainless steel discs. Flocked swab has already been used to recover infectious agents from various surfaces [23]. The recovering of virus with flocked swabs, as described in the present study, opens up the possibility to test the virucidal effect of airborne disinfectants on viruses applied on various surfaces regardless of their size.