Antimicrobial Coatings to Combat Health-Care Acquired Infection

G. Srinivas, M.V. Mundschau, S.N. Paglieri, T. Scholten
TDA Research, Inc.,
United States

Keywords: copper-alloy, stainless steel, S.auerus, catalytic, hydroxyl radical

Summary:

According to statistics of the Center for Disease Control, ~10% of all U.S. patients now acquire communicable diseases from healthcare environments, and every 5.2 minutes a patient dies from such infection while an additional, ~2 million annual non-fatal cases suffer great loss of quality of life and incur costs estimated at $45 billion per year for treatment and rehabilitation. Healthcare-associated illness is now the 3rd leading cause of death in the U.S., exceeded by only cancer and heart disease. Pathogen-contaminated high-touch surfaces may be responsible for nearly 40% of such infections. Clinical tests at Sloan Kettering and military and veterans’ hospitals show unambiguously that up to 40% of Hospital Acquired Infection (HAI) is eliminated by replacing only a few very high-touch surfaces with ones made of pure copper. Critical items include bed side-rails, nurse call buttons, visitor-chair arm rests, over-bed tray tables, IV posts and computer mice. A high microorganism burden remains on these high-touch items after routine cleaning, and infection is transmitted between patients and staff who touch microbial-contaminated surfaces. In general, it will not be practical to replace all high-touch surfaces in hospitals, clinics, nursing homes and medical transport systems with pure copper, which is cost prohibitive and which easily corrodes. TDA Research, Inc. in Golden, Colorado, is developing copper-based coatings that can be applied to stainless-steel surfaces harboring disease organisms. The copper-based coatings are designed to catalytically produce hydroxyl radicals for oxidation of spore and virus coatings. Many published studies demonstrate the broad-spectrum anti-microbial efficacy of copper and copper alloys. Solid, pure copper and many of its alloys destroy a wide variety of microorganisms, including bacteria, bacterial spores, fungal organisms including Aspergillus, and viruses including Norovirus. Copper and its alloys are extremely effective antimicrobial agents due to multiple distinct and effective kill mechanisms. The most effective is the catalytic production of highly reactive oxygen species and especially hydroxyl radicals, hydrogen peroxide, superoxide anions and hydroperoxide radicals that oxidize even the most refractory spore and viral coatings. Moreover, copper ions bind to and deactivate the active sites of microbial enzymes that are excreted by microorganisms to protect them from oxidation. Copper also binds to and deactivates microbial-enzyme active sites within the microorganisms as well as on cell membranes, ligating especially with sulfur and nitrogen functional groups. Copper also binds to the nitrogen of nucleotides in RNA and DNA. In one of the more potent kill mechanisms, Cu1+ and Cu2+ ions, which have sizes similar to K1+ and Na1+, respectively, open the cell-membrane Na1+ and K1+ ion channels, destroying the semi-permeable properties of the membranes and causing microorganisms to rupture. The efficacy of copper as an antimicrobial agent is due to multiple kill mechanisms that are simultaneously active. The outstanding oxidation potential is capable of destroying all classes of pathogen, including bacteria, fungi and viruses, including also dry oxidation of spore and virus coatings.