Bacterial resistance is futile against wound-cleaning laser

June 30, 2008

A laser-activated antimicrobial offers hope for new treatments of bacterial infections, even those that are resistant to current drugs. Research published today in the open access journal BMC Microbiology describes the use of a dye, indocyanine green, which produces bacteria-killing chemicals when lit by a specific kind of laser light.

Michael Wilson led a team from UCL (University College London) who carried out experiments showing that activated indocyanine green is capable of killing a wide range of bacteria including Staphylococcus aureus, Streptococcus pyogenes and Pseudomonas aeruginosa. The dye is safe for humans. The strength of this new approach lies in the variety of ways in which the chemicals produced by the activated dye harm bacteria. As Wilson explains, this means that resistance is unlikely to develop, "The mechanism of killing is non-specific, with reactive oxygen species causing damage to many bacterial components, so resistance is unlikely to develop - even from repeated use". Michael Wilson's co-authors on the study include Ghada Omar and Sean Nair of the Division of Microbial Diseases, UCL Eastman Dental Institute.

The increasing occurrence of bacterial resistance is a well-known problem facing modern medicine. The laser-powered treatment described in the study will be useful in the treatment of infections that occur in wounds. According to Wilson "Infected wounds are responsible for significant morbidity and mortality, and an increase in the duration and the cost of hospital stay. The growing resistance to conventional antibiotics among organisms that infect wounds and burns makes such infections difficult to treat. The technique we are exploring is driven by the need to develop novel strategies to which pathogens will not easily develop resistance."

The laser used by the researchers emits 'near-infrared' light, which is known to be capable of producing heat. However, as Wilson describes, "Substantial killing of all of the bacteria tested was achieved without causing any temperature rise. The benefit of the laser described in this study is that it produces light that is more able to penetrate deep wounds, increasing the area cleansed".
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Notes to Editors

1. Lethal photosensitization of wound-associated microbes using indocyanine green and near-infrared light
Ghada S Omar, Michael Wilson and Sean P Nair
BMC Microbiology (in press)

During embargo, article available here: http://www.biomedcentral.com/imedia/3062155821671394_article.pdf?random=868731

After the embargo, article available at journal website: http://www.biomedcentral.com/bmcmicrobiol/

Please name the journal in any story you write. If you are writing for the web, please link to the article. All articles are available free of charge, according to BioMed Central's open access policy.

Article citation and URL available on request at press@biomedcentral.com on the day of publication.

2. BMC Microbiology is an open access journal publishing original peer-reviewed research articles in analytical and functional studies of prokaryotic and eukaryotic microorganisms, viruses and small parasites, as well as host and therapeutic responses to them. BMC Microbiology (ISSN 1471-2180) is indexed/tracked/covered by PubMed, MEDLINE, BIOSIS, CAS, Scopus, EMBASE, Thomson Scientific (ISI) and Google Scholar.

3. BioMed Central (http://www.biomedcentral.com/) is an independent online publishing house committed to providing immediate access without charge to the peer-reviewed biological and medical research it publishes. This commitment is based on the view that open access to research is essential to the rapid and efficient communication of science.

BioMed Central

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