Got it covered: The coatings that help control infections

Dr Michail Karavolos from antimicrobial technology specialist, BioCote, shares his expertise on coatings that control infections.

Measures to control the spread of infection are widely practiced, but limited, so a proven complementary strategy is to integrate antimicrobial additives into plastic and polymer surfaces to make them inhospitable to bacteria.

With Public Health England predicting that increasing antibiotic resistance could lead to 10 million deaths by 2050 worldwide, plus leading economist Lord Jim O’Neill saying it could also cost the global economy $100 trillion, reducing healthcare-associated infections (HCAIs) can only be achieved by healthcare and pharmaceutical managers being more open to innovative technologies.

The current HCAI regime of infection prevention and control strategies (including hand hygiene, cleaning and training procedures) has long proven to be ineffective, with 16 million extra days of hospital stay required (World Health Organisation, WHO) and 37,000 attributable deaths in Europe each year (European Centre for Disease Prevention and Control), plus annual financial losses of approximately €7 billion in Europe (WHO).

What’s more, healthcare settings themselves play a major part in spreading the infections. Along with other highly populated environments, they are a breeding ground due to shared facilities and enclosed environments, circulated air, common contact surfaces and extended mixing. Common disinfectants have limited residual effects and bacterial populations are rapidly displaying increased resistance to them.

Silver (and copper) has historically been used to preserve food and ward off infection and its antimicrobial properties have been utilised by a range of civilisations up to the present day. However, their use in medical and public health applications waned following the proliferation of the antibiotic industry after World War II - until the emergence of healthcare-associated, multi-drug resistant, disease causing bacteria led to the incorporation of inorganic antimicrobials again; but this time into plastics and other polymerised materials.

Today, BioCote silver ion antimicrobial technology makes all kinds of medical surfaces inhospitable to pathogenic microorganisms. It has no specific site of microbial attack, making evolution of resistance extremely difficult - destroying up to 99.99% of harmful bacteria, fungi (including invasive Candida species e.g., Candida auris), and even viruses like H1N1, H7N9 and the recent Aussie flu strain - through proven protein and oxidative damage, membrane disruption and DNA interference.

Additives are simply and cost effectively incorporated into a variety of substrates such as polycarbonate and ABS during the manufacturing process and exert, by either chemical or mechanical means, a negative effect on any contaminating microbe causing them to die.  

Consequently, multi-modal antimicrobial silver is effective against a wide range of leading superbugs, including MRSA (a multi‑drug resistant variant of Staphylococcus aureus) which is responsible for a range of complications such as skin infections and more seriously blood infections.

It also kills VRE and other gram positive bacteria such as Enterococcus spp, which are resistant to vancomycin and cause severe gastrointestinal conditions and are evidenced to survive for many months on hard surface.

Equally susceptible to silver in an ionic state are gram negative ESBL or Extended Spectrum Beta Lactamase bacteria like E. coli, which is particularly prevalent in the UK and best known for disease related to the urinary tract. Likewise, carbapenem resistant Enterobacteriaceae (CRE) and carbapenemase-producing Enterobacteriaceae (CPE) like Klebsiella pneumoniae – particularly nasty causes of surgical wound infection that produce the enzyme (carbapenemase) to inactivate the antibiotic – are rendered defunct too.

Pseudomonas is a separate family (Pseudomonadaceae) but very similar to Enterobacteriaceae and Acinetobacter is another (Moraxellaceae) but also very similar to Enterobacteriaceae - and one can very reliably predict that because all of these are Gram negative bacteria, the susceptibility to silver will be very similar.

Along with Acinetobacter and Pseudomonas, CPE has been classed as the most ‘critical’ group of bacteria by the WHO, because it poses a particular threat in hospitals, nursing homes, and among patients whose care requires devices such as ventilators and blood catheters.

CPE also encompasses the likes of Escherichia, Shigella and Salmonella and having been evidenced to survive for many months on hard surfaces can cause severe, sometimes deadly, infections like septicaemia and pneumonia. Plus, hospital mortality rates are currently between 40-50%, further lending to CPEs alarming title of ‘seriously emerging infectious disease’.

With the numbers of antibiotic resistant bacteria continuing to grow, current methods to control multi-drug resistant pathogenic bacteria are increasingly limited. However, BioCote antimicrobial technology can successfully be combined with thorough hand-washing practices and regular cleaning to minimise cross-contamination and become an essential, proactive and far reaching element of healthcare infection control.

Because it does not wear out or wipe off surfaces, it can provide a continuous decontamination effect and in a ‘live’ 18-month hospital case study, antimicrobial protected polymers regularly demonstrated significant reductions in bacteria. This peer reviewed study, first published in the Journal of Infection Prevention, demonstrated up to 98% reduction in bacteria between two wards, where ‘ward A’ contained BioCote treated products and ‘Ward B’ non‑treated products.

A similar study in a care home over a five month period, demonstrated a 95% reduction in total microorganism counts when comparing a unit (bedroom and bathroom) with and without BioCote antimicrobial treated products – this peer-reviewed study was first published in Wound Care and the British Journal of Community Nursing.

Indeed, in both studies results also indicated lower numbers of bacteria on other untreated surfaces too, due to the fact there are fewer bacteria being transferred, so using a number of antimicrobial objects in hygiene conscious settings even helps reducing the chance of pathogen spread to the wider untreated environment and causing disease.

Going one step further, a study in collaboration with Birmingham University demonstrated visually, via epifluorescent microscopy and molecular dyes, the ability of BioCote antimicrobial technology to inhibit biofilm formation on treated plastic.

The test organism for this work was Pseudomonas aeruginosa (ubiquitous in the environment and a problematic disease-causing bacterium, particularly in the immune compromised and in healthcare settings) and via the international standard IS022196:2011 – which is the most appropriate standard for quantifying the performance of potentially antimicrobial polymers - it exhibited a highly significant antimicrobial action (99.7% reduction) against P. aeruginosa whilst in its biofilm state.

Since antimicrobials first appeared, there is now the capacity to treat a plethora of material types and silver ions especially with their very high efficacy and non-toxic properties can quite easily be manufactured into plastics and polymers, but also paints, textiles, fabrics, ceramics, paper, etc. They’re environmentally and ecologically acceptable and lots of real data is available from surfaces prevalent in a host of environments, confirming that the efficacy of antimicrobial technology in real-life healthcare settings is comparable with that shown in laboratory validation testing.

Global awareness is such that in nearly any health facility in almost any location you will now find antimicrobial treated materials. Demands are typically highest in Asian territories, followed by North America, then South America with Europe still being the most conservative and slowest to adopt antimicrobial materials as part of everyday surfaces.

Healthcare and pharmaceutical facilities looking to adopt the technology should choose a product containing a regulated antimicrobial that is compliant with BPR/EPA regulations, plus the combinations of additive formulation within the product needs to be appropriate for the market sector. It should also be continuously quality control tested to guarantee high levels of antimicrobial performance and not just during the initial development of the treated product/surface/material.

The additive manufactured into the product is best supplied by an experienced and trusted antimicrobial solutions provider too, while the product has to be correctly labelled in line with the classifying, labelling and packaging guidelines for treated articles.

If a healthcare facility was to embark on a refurbishment program of a particular department they could make a big starting difference with key touch points, like door handles, soap dispensers, grab rails, etc, all cost effectively converted and as this type of technology significantly reduces the potential for stains and odours caused by microbes, it also keeps susceptible medical products fresher for longer and makes them much more hygienic.

Granted, antimicrobial technology doesn’t remove the need for regular cleaning, but it is arguably the best complementary strategy with integrated antimicrobial polymer protection providing a much more comprehensive and robust solution to cross contamination within hospitals, pharmacies and care homes.

With our ageing population, this duty of care approach and second line of defence strategy is increasingly important and relevant.