A bug-free zone

Microbiology is one of the oldest scientific disciplines. We know micro-organisms are crucial for life on earth because they medicate mineral cycling but they also produce a wide range of undesirable effects such as human disease and material degradation.
    
Opposing these effects has naturally occupied microbiologists who inevitably have had to resort to man-made and naturally-occurring substances that display antimicrobial properties.
    
Antimicrobials are discussed frequently in the modern world, primarily with regard to the continuing emergence of bacterial resistance to antibiotics. Since their discovery in the early 20th century, antibiotics have been utilised in widespread applications with real success.
    
After decades of reliable use, we are now aware of the fact that various medically-important bacteria have acquired resistance to commonly prescribed antibiotics.     

The concern of antibiotic resistance is starting to be realised as the possibility of no effective treatment for even relatively minor infections.

THE BIGGER PICTURE

Whilst bacterial resistance to antibiotics is somewhat newsworthy and certainly of concern there is considerably more to the world of antimicrobials than this issue. The term antimicrobial also refers to (non-antibiotic) chemicals or other means by which bacteria can be controlled. For members of the public the most commonly encountered antimicrobials are disinfectants, more specifically referred to as biocides or non-agricultural pesticides.
    
Biocides can be conveniently divided into specific categories. In Europe the Biocidal Product Regulation (BPR) is the legal instrument controlling the trade of biocides and categorises biocides into twenty two types. These types are further divided into four groups: disinfectants (on humans, animals or surfaces), preservatives (for wood, plastic etc.), pest control (e.g. rodents) and ‘other’ biocidal products.
    
Disinfectants are usually thought of as being sprayed or wiped onto a surface to remove microbial contamination (in conjunction with cleaning, which removes detritus). However, a surface can be rendered permanently or semi‑permanently antimicrobial by intentionally incorporating a biocide into it. A wide range of biocides, including organics and inorganics, can be used for this type of application.
    
Every biocide has pluses and minuses as a candidate active substance. Nowadays, for example, environmental issues have gained a prominence when biocides are considered for application. Triclosan has been subject to criticism from environmental and government groups internationally for its potential ecological fate and environmental impact. In addition, there is evidence that triclosan can induce bacterial resistance and is connected to hormone disruption in mammals. However, the Food and Drug Administration in the US are currently maintaining the position that triclosan is safe for human use.
    
Inorganics such as silver and zinc avoid much of the bad press associated with actives like triclosan due to their low toxicity to mammals (humans) and the environment. Also these elements are not considered capable of inducing significant bacterial resistance.         
Perhaps the most common surface-integrated biocide is the inorganic element silver.
    
Silver has been used for thousands of years for its potent antimicrobial properties. In the 20th century, silver has been used clinically in burn creams as silver sulfadiazine and to treat the bacterium Neisseria gonorrhoeae by dropping silver nitrate into babies’ eyes that have become infected during birth. Since the discovery and widespread use of antibiotics, however, the clinical use of silver has understandably declined.
    
The chemical stability of silver favours its use in materials including plastics, paints, lacquers and coatings to give manufactured products a sustained antimicrobial effect.

REGULATION
These finished products or ‘treated articles’ (treated with a biocide) are for the first time in Europe facing formal regulation. Up to September 2013 only the biocides themselves were regulated. Now we see legislation being extended to cover product labelling, proof of efficacy and to prevent the use of unregistered biocides being used in the European Union.
    
In practise biocidal regulations are proving complex and the European situation continues to evolve. In the US the regulatory situation is more established because registration requirements and claims language restrictions have been operation for some time. Globally claims for treated articles should be substantiated or at least provable. This can be considered a trading standards issue but may also fall within the scope of biocidal law.
    
Antimicrobial surface efficacy is routinely determined under laboratory conditions to international standards such as ISO22196:2011 ‘Measurement of antibacterial activity on plastics and other non-porous surfaces’. This straightforward method assesses the numbers of bacteria (Escherichia coli and Staphylococcus aureus) before and after exposure to the biocide treated surface, ideally in comparison to an identical but untreated surface. The results will therefore give an indication as to a surface’s potential to eliminate bacteria contaminating its surface.
    
Antimicrobial technology developer BioCote is aware of the challenges manufacturers of treated products face as they supply into the healthcare market. A main challenge is the potential for antimicrobials deployed in the healthcare to promote poor hygiene standards. An educational approach is the best response to this particular issue. An antimicrobial surface can be thought of as providing a continual antimicrobial effect that works best in combination with routine cleaning. The benefits of antimicrobial technology combine well with hygiene awareness, good hand washing and so on.

ANTIMICROBIAL TECHNOLOGY (AM)
An issue occasionally raised by healthcare professionals is that antimicrobial technology needs to be used alongside existing hygiene practises to have the greatest impact. It is true that antimicrobial technology should work in conjunction with cleaning, but it is equally valid to consider the technology provides a level of ‘continuous’ protection above and beyond standard cleaning. A disinfected surface is only clean until re-contaminated, thus the benefit of cleaning only temporary. AM technology works continuously but needs complimenting by regular cleaning to keep the surface clear of debris which antimicrobial technology cannot remove. In general, antimicrobial surface technology should be considered part of, not the complete, solution.
    
BioCote has commissioned a variety of environmental studies to measure the antimicrobial efficacy of its technology deployed in working environments, which will be explored in the next issue of Health Business.

FURTHER INFORMATION
www.biocote.com