An Overview of the Options for Antimicrobial Hard Surfaces in Hospitals - Use of Biocidal Surfaces for Reduction of Healthcare Acquired Infections - page 156

contaminated than non-treated items. Interestingly, counts from silver impregnated
surfaces in wet areas were lower than on silver impregnated surfaces in dry areas,
which suggests the importance of water/relative humidity in the efficacy of
silver AMS.
7.4.2 Chemical
7.4.2.1 Organosilane
Organosilane-based products are composed of silicon with a quaternary ammonium
compound moiety that inactivate microbes through direct contact [ 72 ].
Organosilane products are not new, having been studied since the 1970s [ 101 ].
An in vitro study of an organosilane product demonstrated 1-3 log reductions of
S. aureus (MRSA), P. aeruginosa and E. coli within 30 min [ 102 ].
Two recent in situ evaluations of organosilane products have demonstrated no
impact in terms of reduced levels of contamination [ 72 , 103 ]. These most likely
illustrate the difficulties of achieving a suitable bond between the surface and the
organosilane, rather than a fundamental problem with the efficacy of the chemical
agent. Further studies are required to assess whether there is a useful application of
organosilane products in healthcare facilities.
7.4.2.2 Quaternary Ammonium Compound
Quaternary ammonium compounds (QAC) are commonly used liquid agents for
surfaces disinfection, particularly in the US. A 2006 study by Rutala et al . demon-
strated that QACs have a residual activity when applied to keyboards [ 104 ]. More
recently, a study from the UK demonstrated that a QAC was more effective for
reducing ATP counts than a chlorine dioxide disinfectant [ 105 ]. Novel formulations
based on QAC with residual claims have recently been launched but further studies
are required to evaluate the potential of existing and novel QAC formulations for
producing effective AMS.
7.4.2.3 Light-Activated
Light-activated antimicrobials generate microbicidal reactive oxygen species when
irradiated with light of a suitable wavelength. A range of photosensiters have been
evaluated, including methylene blue, toluidine blue and rose bengal [ 74 , 106 ,
107 ]. Another option is titanium dioxide, which possesses photocatalytic properties
[ 108 , 109 ]. In addition, photocatalytic surfaces can be combined with metals to
enhance their antimicrobial activity [ 75 , 106 ].