The increase in cases of infections due to the exposures to environmental surfaces in hospitals has led to great concern especially due to infections that are methicilin resistant such as Staphylococcus aureus. It is believed that prevention measures such as the use of coatings will reduce the microbial contamination of hospital surfaces. Hospital/healthcare surfaces include: the ward floors, the stethoscope membrane, the hospital kitchen surface, nurse workstations surface, meat and vegetable preparation surfaces, abattoir surfaces, and refrigerator surfaces.
The microbial load of these surfaces if left unchecked can become so high that it becomes the number one cause of illnesses. The development of antimicrobial coating will highly prevent the high chances of infection by reducing the microbial loads of these surfaces.
One way of prevention of microbial contamination of surfaces includes the use of surfaces that make the microbes have difficulty in attaching. One commonly used method is the use of Poly coatings. This is coating of surfaces using poly ethylene glycol (PEG) to prevent the attachment of proteins, microbes and mammalian cells. These polyurethane surfaces involve the deposition of as self assembled monolayer (SAM) followed by its functionalization to have the needed PEG function.
Surfaces made with PEG has anti fouling properties as a result of the PEG chains on the surface and the absence of binding ties, these two factors make it almost impossible for microbes and other disease-causing agents to attach. Another example of antifouling and anti-adhesive coatings uses the diamond-like carbon films (DLC). DLC contains quantities of hydrogen which makes them sometimes to be referred as amorphous hydrogenated carbon. Diamond-like carbon films are prepared through laboratory preparation of plasma enhanced chemical vapor depositions.
Depositions methods like cathodic vacuum arc, pulsed laser and sputtering are also used. DLC films used on surfaces reduce the attachment of microbes of for example stainless steel surfaces. DLC surfaces can also be doped with microbicidal species to make it have not only antimicrobial properties but also anti-adhesive properties. Easy to clean surfaces can also be used in hospitals to prevent microbial adhesion. This refers to the use of surfaces that have a water droplet contact angle of less than 10 degrees or a hydrophobic surface that is more than 140 degrees. Contact angles less than 100 degree lack easy clean features and this means that it is easier for microbes to attach themselves on such surfaces than those that are more than 140 degrees.
The zwitterionic polymer surfaces is another example of an anti-adhesive/antifouling surface that can be used. Polymers with zwitterionic head groups such as poly (carboxybetaine) can be used as surface coatings to prevent microbial attachment. This is because of zwitterionic hydrophilic nature which causes reversible interactions between microbes and the surface thereby discouraging the attachment of cells and microbes. Apart from antifouling and anti-adhesive coatings research is underway for anti-microbial coatings and surface technologies. One such example is the Microbicide-releasing surfaces.
It is already in the market and is widely in use. Micro ban is one such example that works like a disinfectant though they are considered not permanent. Another example is the silver and silver coating surface which uses silver as an anti-microbial agent. The longstanding ability to act as an anti-microbial can be attributed to silvers ability to bond with thiol group of proteins and enzymes. Copper and copper alloy surfaces have also been considered to be hygienic but toxic to microbes. Copper by itself might not be suitable in a hospital setup due to its oxidation nature but copper alloys such as bronze are highly applicable.
Bacteriophage modified surfaces can also be used in hospitals due to their ability to carry out lytic processes i.e. replication of their genetic material into the host till it is lost. Hospitals can also make use of polycationic antimicrobial surfaces. Cations have been seen to kill microbes by damaging of the microbes cell structure. Another method to disinfect a surface will involve the use of light –activated antimicrobial agents (LAAAs). This are non-selective microbicides meaning they have no specific target within a microbe, this means that they can be effective in situations where the microbes become resistant to other microbicides.
There are two main types of LAAAs, the photosensitiser antimicrobials and the titanium dioxide antimicrobials. Photosensitizer antimicrobials were originally used on cancerous tissues and it is expected that the destructive power of the radicals produced by these photosensitizers can be applied on surface coating when it is immobilized in a polymer matrix and applied to the surface. Examples of photosensitizers include: toluidine blue and rose bengal.
Titanium dioxide microbials on the other hand was long discovered in 1985 when it was found out that platinised titanium dioxide if irradiated by the ultra band gap UV radiation acted as a good antimicrobial due to the release of radical species at the catalyst surface. Hydroxyl radicals produced by redox processes on the surface of titanium dioxide are highly reactive and non-selective therefore making the radical species extremely strong biocides.
Hospital acquired infections should be a cause of concern in any country; this is because the hospital is visited by many individuals and if they were to all get infected the situation will be grave. The growing number of resistant microbes should also be a cause of concern. Hospitals should come up with alternative coating of surfaces so as to prevent the spread of diseases that are otherwise manageable. Some of the methods above are already in use and the hospitals should make an effort to put them into use.
Information retrieved from http://www.antimicrobialcopper.com/media/135337/antimicrobial-surfaces-ucl.pdf on 26th March 2011