Specialized cleaning associated with antimicrobial coatings for reduction of hospital-acquired infection: opinion of the COST Action Network AMiCI (CA15114).

Recognized issues with poor hand hygiene compliance among healthcare workers and reports of recontamination of previously chemically disinfected surfaces through hand contact emphasize the need for novel hygiene methods in addition to those currently available. One such approach involves antimicrobial (nano) coatings (AMCs), whereby integrated active ingredients are responsible for elimination of micro-organisms that come into contact with treated surfaces. While widely studied under laboratory conditions with promising results, studies under real-life healthcare conditions are scarce. The views of 75 contributors from 30 European countries were collated regarding specialized cleaning associated with AMCs for reduction of healthcare-associated infection. There was unanimous agreement that generation of scientific guidelines for cleaning of AMCs, using traditional or new processes, is needed. Specific topics included: understanding mechanisms of action of cleaning materials and their physical interactions with conventional coatings and AMCs; that assessments mimic the life cycle of coatings to determine the impact of repetitive cleaning and other aspects of ageing (e.g. exposure to sunlight); determining concentrations of AMC-derived biocides in effluents; and development of effective de-activation and sterilization treatments for cleaning effluents. Further, the consensus opinion was that, prior to widespread implementation of AMCs, there is a need for clarification of the varying responsibilities of involved clinical, healthcare management, cleaning services and environmental safety stakeholders.

Surface modifications for antimicrobial effects in the healthcare setting: a critical overview.

The spread of infections in healthcare environments is a persistent and growing problem in most countries, aggravated by the development of microbial resistance to antibiotics and disinfectants. In addition to indwelling medical devices (e.g. implants, catheters), such infections may also result from adhesion of microbes either to external solid-water interfaces such as shower caps, taps, drains, etc., or to external solid-gas interfaces such as door handles, clothes, curtains, computer keyboards, etc. The latter are the main focus of the present work, where an overview of antimicrobial coatings for such applications is presented. This review addresses well-established and novel methodologies, including chemical and physical functional modification of surfaces to reduce microbial contamination, as well as the potential risks associated with the implementation of such anticontamination measures. Different chemistry-based approaches are discussed, for instance anti-adhesive surfaces (e.g. superhydrophobic, zwitterions), contact-killing surfaces (e.g. polymer brushes, phages), and biocide-releasing surfaces (e.g. triggered release, quorum sensing-based systems). The review also assesses the impact of topographical modifications at distinct dimensions (micrometre and nanometre orders of magnitude) and the importance of applying safe-by-design criteria (e.g. toxicity, contribution for unwanted acquisition of antimicrobial resistance, long-term stability) when developing and implementing antimicrobial surfaces.

Bacterial community changes in copper and PEX drinking water pipeline biofilms under extra disinfection and magnetic water treatment.

AIMS: To study the stability of biofilms and water quality in pilot scale drinking water copper and PEX pipes in changing conditions (extra disinfection, magnetic water treatment, MWT). METHODS AND RESULTS: Next-generation sequencing (NGS) of 16S ribosomal RNA genes (rDNA) to describe total bacterial community and ribosomal RNA (rRNA) to describe active bacterial members in addition to traditional microbiological methods were applied. Biofilms from control copper and PEX pipes shared same most abundant bacteria (Methylobacterium spp., Sphingomonas spp., Zymomonas spp.) and average species diversities (Shannon 3·8-4·2) in rDNA and rRNA libraries, whereas few of the taxa differed by their abundance such as lower total Mycobacterium spp. occurrence in copper (<0·02%) to PEX (<0·2%) pipes. Extra disinfection (total chlorine increase from c. 0·5 to 1 mg l-1 ) affected total and active population in biofilms seen as decrease in many bacterial species and diversity (Shannon 2·7, P < 0·01, rRNA) and increase in Sphingomonas spp. as compared to control samples. Furthermore, extra-disinfected copper and PEX samples formed separate clusters in unweighted non-metric multidimensional scaling plot (rRNA) similarly to MWT-treated biofilms of copper (but not PEX) pipes that instead showed higher species diversity (Shannon 4·8, P < 0·05 interaction). CONCLUSIONS: Minor chlorine dose addition increased selection pressure and many species were sensitive to chlorination. Pipe material seemed to affect mycobacteria occurrence, and bacterial communities with MWT in copper but not in PEX pipes. SIGNIFICANCE AND IMPACT OF THE STUDY: This study using rRNA showed that chlorination affects especially active fraction of bacterial communities. Copper and PEX differed by the occurrence of some bacterial members despite similar community profiles.

Copper as an antibacterial material in different facilities.

The present study was performed in real life settings in different facilities (hospital, kindergarten, retirement home, office building) with copper and copper alloy touch surface products (floor drain lids, toilet flush buttons, door handles, light switches, closet touch surfaces, corridor hand rails, front door handles and toilet support rails) in parallel to reference products. Pure copper surfaces supported lower total bacterial counts (16 ± 45 vs 105 ± 430 CFU cm-2 , n = 214, P < 0·001) and a lower occurrence of Staphylococcus aureus (2·6 vs 14%, n = 157, P < 0·01) and Gram-negatives (21 vs 34%, n = 214, P < 0·05) respectively than did reference surfaces, whereas the occurrence of enterococci (15%, n = 214, P > 0·05) was similar. The studied products could be assigned to three categories according to their bacterial loads as follows (P < 0·001): floor drain lids (300 ± 730 CFU cm-2 , n = 32), small area touch surfaces (8·0 ± 7·1 to 62 ± 160 CFU cm-2 , n = 90) and large area touch surfaces (1·1 ± 1·1 to 1·7 ± 2·4 CFU cm-2 , n = 92). In conclusion, copper touch surface products can function as antibacterial materials to reduce the bacterial load, especially on frequently touched small surfaces. SIGNIFICANCE AND IMPACT OF THE STUDY: The efficiency of copper as an antimicrobial material has been noted in laboratory studies and in the hospital environment. The present study further shows that copper exerted an antibacterial effect in different facilities, i.e. in a hospital, a kindergarten, an office building and in a retirement home for the elderly. The study suggests that copper has potential use as an antibacterial material and therefore might serve as a means to lower the incidence of transmission of infectious agents from inanimate surfaces in different facilities, with everyday functions.

Diversity of ribosomal 16S DNA- and RNA-based bacterial community in an office building drinking water system.

AIMS: Next-generation sequencing of 16S ribosomal RNA genes (rDNA) and ribosomal RNA (rRNA) was used to characterize water and biofilm microbiome collected from a drinking water distribution system of an office building after its first year of operation. METHODS AND RESULTS: The total bacterial community (rDNA) and active bacterial members (rRNA) sequencing databases were generated by Illumina MiSeq PE250 platform. As estimated by Chao1 index, species richness in cold water system was lower (180-260) in biofilms (Sphingomonas spp., Methylobacterium spp., Limnohabitans spp., Rhizobiales order) than in waters (250-580), (also Methylotenera spp.) (P = 0·005, n = 20). Similarly species richness (Chao1) was slightly higher (210-580) in rDNA libraries compared to rRNA libraries (150-400; P = 0·054, n = 24). Active Mycobacterium spp. was found in cross-linked polyethylene (PEX), but not in corresponding copper pipeline biofilm. Nonpathogenic Legionella spp. was found in rDNA libraries but not in rRNA libraries. CONCLUSIONS: Microbial communities differed between water and biofilms, between cold and hot water systems, locations in the building and between water rRNA and rDNA libraries, as shown by clear clusters in principal component analysis (PcoA). By using the rRNA method, we found that not all bacterial community members were active (e.g. Legionella spp.), whereas other members showed increased activity in some locations; for example, Pseudomonas spp. in hot water circulations' biofilm and order Rhizobiales and Limnohabitans spp. in stagnated locations' water and biofilm. SIGNIFICANCE AND IMPACT OF THE STUDY: rRNA-based methods may be better than rDNA-based methods for evaluating human health implications as rRNA methods can be used to describe the active bacterial fraction. This study indicates that copper as a pipeline material might have an adverse impact on the occurrence of Mycobacterium spp. The activity of Legionella spp. maybe questionable when detected solely by using DNA-based methods.