Featured Research

from universities, journals, and other organizations

MRSA Study Suggests Strategy Shift Needed To Develop Effective Therapeutics

Date:
March 23, 2009
Source:
NIH/National Institute of Allergy and Infectious Diseases
Summary:
USA300 -- the major epidemic strain of methicillin-resistant Staphylococcus aureus (MRSA) causing severe infections in the United States during the past decade -- inherits its destructiveness directly from a forefather strain of the bacterium called USA500 rather than randomly acquiring harmful genes from other MRSA strains.

USA300 — the major epidemic strain of methicillin-resistant Staphylococcus aureus (MRSA) causing severe infections in the United States during the past decade — inherits its destructiveness directly from a forefather strain of the bacterium called USA500 rather than randomly acquiring harmful genes from other MRSA strains. This finding comes from a new study led by scientists at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.

Related Articles


The study authors suggest that a radical shift may be needed in how scientists should design MRSA therapeutics. Instead of the current focus on neutralizing MRSA by targeting products of mobile genetic elements — DNA molecules that bacteria acquire randomly by interacting with other bacteria — scientists should switch to looking at the permanent DNA backbone (core genome) of USA300 to understand how increased production of certain proteins such as toxins affects its virulence in humans.

NIAID scientist Michael Otto, Ph.D., directed the study, which involved analyzing DNA sequences of the major epidemic forms of S. aureus. The research team found that the lineage of the bacteria fell into three distinct families: (1) USA300 and its forefather, USA500, which are epidemic in U.S. hospital and community settings; (2) MRSA found primarily in hospitals in the United Kingdom and Europe; and (3) MRSA found in hospitals in South America, Europe and Asia.

The researchers then tested the different lineages in mice, observing that the USA300 and USA500 strains were significantly more destructive than the other strains. Further, when interacting with human immune cells, the USA300 and USA500 strains killed nearly 80 percent of the immune cells, compared with a rate of less than 10 percent for all other strains tested. Finally, when the scientists evaluated what in the bacteria was killing the immune cells, they found that levels of alpha toxin and alpha-type phenol-soluble modulins (PSMs) were significantly higher in USA300 and USA500 compared with the other strains. Earlier NIAID studies determined that alpha toxin and alpha-type PSMs play a crucial role in determining the severity of community-associated MRSA infection.

Another important finding of the study, according to Dr. Otto, is that USA300 and USA500 are nearly identical in virulence, as is their level of virulence gene production. This suggests that the Panton-Valentine leukocidin (PVL) and other mobile genetic elements long believed to play key roles in USA300 virulence have no significant impact, because while USA300 carries the PVL and other mobile genes, USA500 does not.

The researchers now are investigating why USA300 is more widespread than USA500 in U.S. community settings, despite their many similarities.

Dr. Otto's collaborators include scientists from NIAID, the University of California at San Francisco and Huashan Hospital, Shanghai Medical College, Fudan University, in China.


Story Source:

The above story is based on materials provided by NIH/National Institute of Allergy and Infectious Diseases. Note: Materials may be edited for content and length.


Journal Reference:

  1. M Li et al. Evolution of virulence in epidemic community-associated methicillin-resistant Staphylococcus aureus. Proceedings of the National Academy of Sciences, 2009; DOI: 10.1073/pnas.0900743106

Cite This Page:

NIH/National Institute of Allergy and Infectious Diseases. "MRSA Study Suggests Strategy Shift Needed To Develop Effective Therapeutics." ScienceDaily. ScienceDaily, 23 March 2009. <www.sciencedaily.com/releases/2009/03/090317125226.htm>.
NIH/National Institute of Allergy and Infectious Diseases. (2009, March 23). MRSA Study Suggests Strategy Shift Needed To Develop Effective Therapeutics. ScienceDaily. Retrieved November 28, 2014 from www.sciencedaily.com/releases/2009/03/090317125226.htm
NIH/National Institute of Allergy and Infectious Diseases. "MRSA Study Suggests Strategy Shift Needed To Develop Effective Therapeutics." ScienceDaily. www.sciencedaily.com/releases/2009/03/090317125226.htm (accessed November 28, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Friday, November 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ebola Leaves Orphans Alone in Sierra Leone

Ebola Leaves Orphans Alone in Sierra Leone

AFP (Nov. 27, 2014) — The Ebola epidemic sweeping Sierra Leone is having a profound effect on the country's children, many of whom have been left without any family members to support them. Duration: 01:02 Video provided by AFP
Powered by NewsLook.com
Experimental Ebola Vaccine Shows Promise In Human Trial

Experimental Ebola Vaccine Shows Promise In Human Trial

Newsy (Nov. 27, 2014) — A recent test of a prototype Ebola vaccine generated an immune response to the disease in subjects. Video provided by Newsy
Powered by NewsLook.com
Pet Dogs to Be Used in Anti-Ageing Trial

Pet Dogs to Be Used in Anti-Ageing Trial

Reuters - Innovations Video Online (Nov. 26, 2014) — Researchers in the United States are preparing to discover whether a drug commonly used in human organ transplants can extend the lifespan and health quality of pet dogs. Video provided by Reuters
Powered by NewsLook.com
Today's Prostheses Are More Capable Than Ever

Today's Prostheses Are More Capable Than Ever

Newsy (Nov. 26, 2014) — Advances in prosthetics are making replacement body parts stronger and more lifelike than they’ve ever been. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins