Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Golden armor

12.07.2005


UCSD scientist’s discovery suggest new way to fight antibiotic-resistant staphylococcus infections



Researchers at the University of California, San Diego School of Medicine and Children’s Hospital and Health Center, San Diego have discovered that "Staph" bacteria use a protective golden armor to ward off the immune system, a finding with the potential to lead to new treatments for serious infections now increasingly resistant to standard antibiotics.

The research, which is featured on the cover of the July 17, 2005 issue of The Journal of Experimental Medicine, focused on the major human pathogen Staphylococcus aureus and the characteristic yellow-orange color for which it is named ("aureus" is Latin for "golden").


Among the deadliest of all disease-causing organisms, "Staph" is the leading cause of human infections in the skin and soft tissues, bones and joints, abscesses and normal heart valves. Staph especially flourishes in the hospital setting, producing bloodstream and surgical wound infections. The spread of antibiotic resistant strains of Staph, referred to as methicillin-resistant Staphylococcus aureus or MRSA, has reached epidemic proportions and poses a major threat to the public health.

The UCSD team proved for the first time that the golden pigment that coats the surface of Staph is not just for decoration; rather, the molecules that give the bacteria its golden hue also help it resist killing by neutrophils, white blood cells with a front line role in immune defense against invading microbes.

Staph’s coloration reflects the production of molecules called carotenoids, similar to those present in carrots and other colorful vegetables and fruits. Dietary carotenoids have long been touted for their antioxidant properties with hope that they could slow aging or fight off cancer. The scientists found that pathogenic Staph took advantage of the antioxidant effects of its carotenoid pigment to extend its own life, by inactivating chemicals deployed by neutrophils that are lethal to most bacteria. The UCSD team used a molecular genetic approach for their studies, knocking out the genes for carotenoid synthesis to generate a mutant strain of Staph that appeared white in color instead of the normal gold.

"We found that the nonpigmented Staph mutant became much more susceptible to oxidants such as hydrogen peroxide and singlet oxygen produced by neutrophils," said George Liu, M.D., Ph.D., a research fellow in the UCSD department of pediatrics who spearheaded the studies. "Without its golden pigment, the Staph lost its ability to survive in human neutrophils or blood, and could no longer form an abscess when injected into the skin of experimental mice."

The investigators proved that the antioxidant effects of the Staph pigment were the key factor in virulence by repeating experiments in blood from a human patient with chronic granulomatous disease (CGD), an inherited disorder in which neutrophils cannot produce oxidants and infections are common, as well as in mice engineered to possess the same genetic mutation. Without the oxidant assault, the ability of the nonpigmented strain to resist neutrophil killing and produce disease was equal to the golden Staph.

The power of the antioxidant pigment in promoting bacterial survival was further established extending the protective properties to a different bacteria. Pigment-producing genes of Staph were cloned into a normally colorless strain of Streptococcus ("Strep") bacteria that then turned yellow in color. The Strep expressing the golden carotenoid pigment became more resistant to oxidant and neutrophil killing, and produced larger ulcers when injected into the skin of normal mice.

"The discovery of the critical role played by golden pigment in protecting against infection provides an novel target for treatment of serious Staph infections including those produced by antibiotic-resistant MRSA," said senior author Victor Nizet, M.D., UCSD associate professor of pediatrics and an infectious diseases physician at Children’s Hospital, San Diego. "Instead of attempting to kill the bacteria directly with standard antibiotics, a treatment strategy to inhibit the Staph pigment would disarm the pathogen, making it susceptible to clearance by our normal immune defenses"

Leslie Franz | EurekAlert!
Further information:
http://www.ucsd.edu

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>