Disastrous performance of NanoCote/Aqua Based antimicrobial paint in a hospital setting

Abstract

There is considerable interest in the potential of antimicrobial surfaces in hospitals to reduce hospitalacquired infections (HAI). Two principal questions need to be answered: (1) are inanimate surfaces important reservoirs for microbes? and (2) can antimicrobial surfaces reduce the environmental microbial burden? The answer to (1) is far from clear, with both “yes” [1] and “no” [2] being promulgated. Nevertheless, it has at least been conceded that microbial contamination on surfaces can be, and probably is, transferred to patients via human hands [3] (while noting that well-designed studies demonstrating that point, or its converse, are so far lacking). If so, proper hand hygiene might be the answer, although Dancer has pointed out that it is, practically, easier to improve cleaning than hand hygiene [4], since the latter, more profoundly than the former, involves behavioural change rather than merely setting up a “standard operating procedure” (SOP) or similar. The answer to (2) is more straightforward: the burden can be reduced and quite a few technologies are now available for doing so [5], which might help to overcome some of the difficulties associated with conventional disinfection [6]. Recently, considerable interest has been shown in copper as an antimicrobial material. Appreciation of its efficacy probably goes back for several millennia, and quite a few studies have succeeded in demonstrating it more or less quantitatively [7–10]. In a frequently-cited paper, Salgado et al. went as far as asserting that copper surfaces reduce the rate of HAI [11]; the critique of this study [12], which effectively negates its conclusions, is unfortunately much less cited. Even if the link between antimicrobial activity at a surface and reduction of HAI remains to be convincingly demonstrated (cf. [13]), it is certainly plausible enough to warrant further investigation of the antimicrobial effect of different surfaces. Making hospital artefacts from copper may be expensive, aesthetically questionable and impracticable to retrofit. In order to counter those difficulties, there has been some interest in depositing thin films of copper on surfaces made from other materials (e.g. [14]), but this is obviously only possible for objects small enough to fit inside a vacuum chamber. A more useful approach may be to nanify the copper and incorporate it into a paint or varnish that can be readily applied to existing services. The bactericidal activity of copper nanoparticles has been demonstrated [15] (as well as that of copper oxide [16]). Cometa et al. have shown that this activity is retained upon entrapment of the particles in a hydrogel [17], and similarly with conventional polymers [18]. The effective encapsulation of the copper may, furthermore, diminish possible dermatological problems arising through copper hypersensitivity [19, 20]. Disastrous performance of NanoCote/Aqua Based antimicrobial paint in a hospital setting