BackgroundBacterial resistance against the classic antibiotics is posing an increasing challenge for the prevention and treatment of infections in health care environments. The introduction of antimicrobial nanocoatings with active ingredients provides alternative measures for active killing of microorganisms, through a preventive hygiene approach.PurposeThe purpose of this study was to investigate the antimicrobial activity of a panel of antimicrobial coatings available on the European market.MethodsA comparative, biased selection of commercially available antimicrobial coatings was tested for antimicrobial efficiency. Suppliers were contacted to deliver their coatings on glass and/or stainless steel substrates. In total, 23 coatings from eleven suppliers were received, which were investigated for their effect on the growth of Escherichia coli, using the International Organization for Standardization (ISO) 22196 protocol.ResultsThe majority of nanomaterial-containing coatings (n=13) contained nanosilver (n=12), while only one had photocatalytic TiO2 as the active particle. The differences in antimicrobial activity among all of the coatings, expressed as log reduction values, varied between 1.3 and 6.6, while the variation within the nanomaterial-based group was between 2.0 and 6.2. Although nanosilver coatings were on average very effective in reducing the number of viable bacteria after challenge, the strongest log reduction (6.6) was seen with a coating that has immobilized, covalently bound quaternary ammonium salt in its matrix. Besides these two compounds, coatings containing TiO2, poly(dimethylsiloxane), triclosan, or zinc pyrithione evoked 100% killing of E. coli.ConclusionOur findings indicate that nanosilver dominates the nanoparticle-based coatings and performs adequately. However, considering the unknowns in relation to ecotoxicological emission and effects, it needs further consideration before widespread application into different environments.

Worldwide, millions of patients are affected annually by healthcare-associated infection (HCAI), impacting up to 80,000 patients in European Hospitals on any given day. This represents not only public health risk, but also an economic burden.Complementing routine hand hygiene practices, cleaning and disinfection, antimicrobial coatings hold promise based, in essence, on the application of materials and chemicals with persistent bactericidal or –static properties onto surfaces or in textiles used in healthcare environments.The focus of considerable commercial investment and academic research energies, such antimicrobial coating-based approaches are widely believed to have potential in reduction of microbial numbers on surfaces in clinical settings. This belief exists despite definitive evidence as to their efficacy and is based somewhat on positive studies involving, for example, copper, silver or gold ions, titanium or organosilane, albeit under laboratory conditions. The literature describes successful delay and/or prevention of recontamination following conventional cleaning and disinfection by problematic microbes such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE), among others. However, there is a scarcity of studies assessing antimicrobial surfaces other than copper in the clinical environment, and a complete lack of published data regarding the successful implementation of these materials on clinically significant outcomes (including HCAI).Through its Cooperation in Science and Technology program (COST), the European Commission has funded a 4-year initiative to establish a network of stakeholders involved in development, regulation and use of novel anti-microbial coatings for prevention of HCAI. The network (AMiCI) comprises participants of more than 60 universities, research institutes and companies across 29 European countries and, to-date, represents the most comprehensive consortium targeting use of these emergent technologies in healthcare settings.More specifically, the network will prioritise coordinated research on the effects (both positive and negative) of antimicrobial coatings in healthcare sectors; know-how regarding availability and mechanisms of action of (nano)-coatings; possible adverse effects of such materials (e.g., potential emergence of microbial resistance or emission of toxic agents into the environment); standardised performance assessments for antimicrobial coatings; identification and dissemination of best practices by hospitals, other clinical facilities, regulators and manufacturers.