Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Studies highlight MRSA evolution and resilience

22.01.2008
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are caused primarily by a single strain—USA300—of an evolving bacterium that has spread with “extraordinary transmissibility” throughout the United States during the past five years, according to a new study led by National Institutes of Health (NIH) scientists. CA-MRSA, an emerging public health concern, typically causes readily treatable soft-tissue infections such as boils, but also can lead to life-threatening conditions that are difficult to treat.

The study, from the National Institute of Allergy and Infectious Diseases (NIAID) of NIH, resolves debate about the molecular evolution of CA-MRSA in the United States. The findings rule out the previously held possibility that multiple strains of USA300, the most troublesome type of CA-MRSA in the United States, emerged randomly with similar characteristics. The study also offers a hypothesis for the origin of previous S. aureus outbreaks, such as those caused by penicillin-resistant strains in the 1950s and 1960s.

A second study led by the same NIAID scientists takes the issue of the evolution of MRSA a step further, revealing new information about how MRSA bacteria in general, including the USA300 group, elude the human immune system.

The first study, which appears online this week in the Proceedings of the National Academy of Sciences, found that the USA300 group of CA-MRSA strains, collectively called the epidemic strain, comprises nearly identical clones that have emerged from a single bacterial strain. It is the first time scientists have used comparative genome sequencing to reveal the origins of epidemic CA-MRSA. Frank R. DeLeo, Ph.D., at NIAID’s Rocky Mountain Laboratories (RML) in Hamilton, Mont., led the research.

“Scientists are pressing ahead quickly to learn more about how some MRSA strains evade the immune system and spread rapidly,” says NIAID Director Anthony S. Fauci, M.D. “The information presented in these two studies adds important new insights to that expanding knowledge base.”

To understand how CA-MRSA is evolving in complexity and spreading geographically, Dr. DeLeo’s group sequenced the genomes of 10 patient samples of the USA300 bacterium recovered from individuals treated at different U.S. locations between 2002 and 2005. They then compared these genomes to each other and to a baseline USA300 strain used in earlier studies. Eight of the 10 USA300 patient samples were found to have nearly indistinguishable genomes, indicating they originated from a common strain. The remaining two bacteria were related to the other eight, but more distantly.

Interestingly, of the eight nearly indistinguishable USA300 patient samples, two caused far fewer deaths in laboratory mice than the others, highlighting an emerging view that tiny genetic changes among evolving strains can profoundly affect disease severity and the potential for drug resistance to develop.

“The USA300 group of strains appears to have extraordinary transmissibility and fitness,” says Dr. DeLeo. “We anticipate that new USA300 derivatives will emerge within the next several years and that these strains will have a wide range of disease-causing potential.” Ultimately, Dr. DeLeo and his colleagues hope that the work will lead to the development of new diagnostic tests that can quickly identify specific strains of MRSA.

Fred C. Tenover, Ph.D., of the Centers for Disease Control and Prevention in Atlanta (CDC) contributed the 10 USA300 clinical isolates from CDC’s Active Bacterial Core Surveillance system. Other study collaborators included Barry N. Kreiswirth, Ph.D., of the International Center for Public Health (ICPH) in Newark, N.J., and James M. Musser, M.D., Ph.D., of The Methodist Hospital Research Institute in Houston.

The second report, which involved scientists from RML, ICPH and Vanderbilt University Medical Center in Nashville, was recently published online in the Journal of Immunology. This study provides scientists with new details about the complex mechanisms MRSA uses to avoid destruction by neutrophils, human white blood cells that ingest and destroy microbes. When exposed to hydrogen peroxide, hypochlorous acid (the active component of household bleach) or antimicrobial proteins—all killer chemicals released by neutrophils—MRSA senses danger, escapes harm and turns the tables on the white blood cells, destroying them. Work is continuing in Dr. DeLeo’s lab to understand how the bacterium senses and survives attacks by neutrophils.

Ken Pekoc | EurekAlert!
Further information:
http://www.nih.gov

More articles from Studies and Analyses:

nachricht New study: How does Europe become a leading player for software and IT services?
03.04.2017 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)

nachricht Reusable carbon nanotubes could be the water filter of the future, says RIT study
30.03.2017 | Rochester Institute of Technology

All articles from Studies and Analyses >>>

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

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

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Scientist invents way to trigger artificial photosynthesis to clean air

26.04.2017 | Materials Sciences

Ammonium nitrogen input increases the synthesis of anticarcinogenic compounds in broccoli

26.04.2017 | Agricultural and Forestry Science

SwRI-led team discovers lull in Mars' giant impact history

26.04.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>