New research suggests products being used in hospitals to prevent the spread of bacteria could in fact be accelerating the development of antibiotic- and biocide-resistant strains.

Biocides, which are active in many disinfectants used in hospitals and health care environments - in particular triclosan and quaternary ammonium compounds - act on bacteria in a similar way to antibiotics.

They do this by activating efflux pumps in the membranes of bacterial cells. The pumps are natural protection mechanisms that remove unwanted substances out of the cell.

Low level exposure to biocides increases the activity of efflux pumps, meaning bacteria are also increasingly able to resist the effects of antibiotics.

Genetic mutation can also increase the efficiency of efflux pumps. Depending on the environment in which the bacteria are growing, those that have stronger resistance to threatening substances will survive and create resistance among a population.

Because some biocides are also capable of carrying mobile genetic elements, or plasmids, biocides can even stimulate cross-resistance between biocides and antibiotics.

Of particular concern is the widespread use of silver in hospital products and devices. Healthcare is the largest consumer of silver of all the industrial sectors.

Silver’s natural anti-bactericidal qualities has lead to application not only in wound care and bone prostheses, but more recently to a wide range of other products and materials including soaps, textiles, walls, floors, as well as clothes and shoes.


However, researchers at Uppsala University in Sweden have found that this continuous use of silver in healthcare environments could be making bacteria resistant not only to the effects of silver, but even to certain antibiotics.

One such class of antibiotics, beta-lactam, accounts for 50% of antibiotic treatment.

While the benefits of silver are widely recognised, little attention has been paid to the potential risks of continuous use of silver and its possible contribution to antibiotic resistance.

Recent findings published by the European Commission show very little is known about the potential effects of biocidal products in healthcare environments.

Asa Melhus, Associate Professor in Clinical Microbiology from Uppsala University, said that despite a lack of conclusive evidence, the risk of a link should be enough to get the attention of the health care industry.

She said: “Even if there was no connection between biocides and antibiotics... biocide resistance is itself scary. Infection control measures have saved more lives than antibiotics.

“If we cannot eradicate bacteria in the hospital environment with biocides, hospitals may become death traps.”

Without a full understanding of the causes of biocidal resistance, the researchers at Uppsala have warned that, instead of improving hygiene, the widespread use of biocides like silver could increase the risk of serious bacterial infections in hospitals.


by James Black, Health & Environment writer
Health and Environment No.14, May 2009 (formerly HCWH Europe Newsletter)