Which metal is antibacterial

Stainless steel versus copper in the fight against germs ... from the perspective of the stainless steel lobby

(17.12.2009) The Trademark Association of Stainless Steel Rostfrei e.V. sees the leading role of stainless steel in matters of hygiene and health care based on the state of science in the ...

  • permanent resistance to mechanical stress as well as disinfectants and cleaning agents as well as in the
  • inert, extremely smooth surface of the robust material.

However, the antibacterial effect of copper as a "germ killer" has been intensified again at the moment - see, for example, the article "Copper against germs: expectations were exceeded" from July 2nd, 2009. However, according to a new study by the Institute for Hygiene and Public Health (IHPH) at the University of Bonn, significant known weaknesses as well as the previously unexplained consequences of the material copper are ignored.

Dangerous germs are increasingly on the rise in hospitals and medical facilities. Every tenth patient who is admitted to a hospital in the European Union (EU) becomes infected there. Of these roughly three million people, according to a current estimate by the European Center for Disease Control and Prevention (ECDC), 37,000 die from a nosocomial infection acquired in hospital. In Germany alone, according to surveys by the German Society for Hospital Hygiene (DGKH), the annual infection rate is over 500,000 patients. The National Reference Center for Surveillance of Nosocomial Infections (NRZ) in Berlin estimates that around 7,500 deaths annually in Germany alone can be attributed to hospital germs. The NRZ considers 20 to 30% of these deaths to be preventable. Absolute hygiene, especially with frequently touched contact surfaces, is of great importance here.

Five germs are considered to be particularly common triggers for hospital infections:

  • MRSA (methicillin-resistant Staphylococcus aureus),
  • ORSA (Oxaxillin-Resistant Staphylococcus Aureus),
  • VRSA (Vancomycin-Resistant Staphylococcus Aureus),
  • VRE (Vancomycin Resistant Enterococci) and
  • ESBL (Extended Spectrum Beta-Lactamases).

After the operation of immunocompromised patients, these germs lead to complications that are often fatal, such as pneumonia, blood poisoning and / or urinary tract infections. The main routes of transmission of the pathogens are direct contact via the hands and surfaces that are often touched, such as doorknobs, light switches, sanitary fittings, bed frames or bedside tables. In order to interrupt these routes of infection, it is necessary to reduce the risk of contamination by means of systematic cleaning, disinfection and sterilization of component and furniture surfaces as well as instruments. In this context, the nature of the contact surfaces as the location of the colonization and transmission of germs is of decisive importance. The search for the hygienically optimal material for these surfaces requires a systemic consideration: the antibacterial effect of copper has been known since ancient times. Nevertheless, science and medical technology have relied on stainless steel for decades in particularly hygienic environments. The reason lies in the holistic, safe fulfillment of the strictest hygiene requirements.

Permanently inert

The passive layer is characteristic of stainless steel. The particularly smooth, inert surface prevents ions from escaping. Copper, on the other hand, releases ions. These ions act like an antibiotic in that they can penetrate the bacterial cell and destroy it. However, bacteria develop resistance to antibiotics. So far, it has not been clarified in this context whether they react analogously to copper ions and thus render them ineffective.

Permanently smooth

The scratch- and abrasion-resistant stainless steel surface is extremely smooth even after years of continuous use, so that bacteria cannot find a breeding ground. In contrast, the significantly softer surface of copper is easily scratched and roughened in daily use. This creates depressions that promote bacterial colonization - if not accelerate it. The increased surface roughness increases the risk of increasing contamination, which in turn increasingly prevents the ions from escaping.

Permanently non-reactive

Agents used in hospitals for cleaning or disinfecting should not be able to attack the inert surface of stainless steel, so that no interactions between the metal surface and cleaning agents occur. An interaction of the material with the environment, such as a reaction with atmospheric oxygen, can just as reliably be ruled out. Copper, on the other hand, can tarnish and form a greenish patina through regular treatment with the acidic or oxidative cleaning agents and disinfectants usually used in hospitals. This change in the surface not only gives the impression of poor hygiene, but also means that the surface is actually harder to clean. This also reduces the ion permeability and consequently the antibacterial effect. The sum of the factors influencing the release of ions illustrates the uncertainty as to whether the antibacterial effect of copper will remain consistently high.

"Permanently safe"

The overall view shows that the robust, inert surface of stainless steel meets high long-term requirements - with unchanged surface properties and reliably predictable constancy. Isolated considerations of individual properties such as the antibacterial effect do not do justice to the complex overall context. Only the combined resistance to chemical and mechanical stress - combined with effective cleaning and disinfection systems - guarantees permanently reliable quality, hygiene and aesthetics. Stainless steel with a seal of approval makes a lasting contribution to reducing the risk of infection for patients, hospital employees and visitors.

Further information can be obtained by Email to the stainless steel trade mark association be requested.

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