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Tuesday July 10 1:26 AM ET
Staph Bacteria Active Gene Swapper
By PAUL RECER, AP Science Writer
WASHINGTON (AP) - Staph bacteria can quickly swap genes with relatives to turn into virulent, dangerous germs that can cause disease and resist antibiotics, a
new study shows.
In a report appearing Tuesday in the Proceedings of the National Academy of Sciences, federal researchers said they used a new technology to learn that
Staphylococcus aureus could grab new genes from nearby bacteria to adapt itself to a changing environment.
Staphylococcus aureus, or staph, is an extremely troublesome bacterium that causes a variety of illnesses. It is a major cause of hospital-acquired infection. Staph
causes such things as the scalded skin disease that strikes infants, toxic shock syndrome and systemic blood poisoning called sepsis.
Antibiotics once controlled the bacteria, but strains of staph are now resistant to the drugs.
``This is the first time we've been able to do such an extensive genetic comparison of these strains of Staphylococcus aureus,'' said Dr. James M. Musser, senior
author of the study and head of a bacterial research lab at the National Institute of Allergy and Infectious Disease's Rocky Mountain Laboratories in Hamilton, Mont.
NIAID is one of the National Institutes of Health.
In the study, Musser and his colleagues analyzed the genes of 36 of the most troublesome strains of staph and concluded that virtually any of the bacteria's 2,817
strains could acquire the genes to become resistant to antibiotics.
``This is occurring at a far more greater frequency than we anticipated,'' said Musser. ``The drug resistant strains can be created many times. It is not a single strain
that is created once and then spreads.''
Instead, he said the genetic combination that provides resistance can arise independently in many different places, many different times.
Such an easy evolution of drug resistance ``has sent a wave of terror through people responsible for public health,'' said Dr. Abigail A. Salyers, a microbe researcher
at the University of Illinois, Urbana. ``They know this organism will become a major pathogen if antibiotics no longer work.''
Salyers, who is president of the American Society for Microbiology, said the work by Musser and his group is important because it confirms what has long been
suspected - that whole gene structures can jump from bacteria to bacteria, creating new strains of antibiotic resistant bugs within a matter of hours.
``One of the important findings in this paper is that the anti-bacterial resistance gene is being acquired by lateral transfer,'' or from bacteria-to-bacteria, she said. This
has long been suspected, but Salyers said the Musser paper presents new evidence.
Staph is among the most common human bacteria, carried by about a third of the population. It can be picked up from countertops or door knobs, but is more
frequently transferred through skin-to-skin contact, such as shaking hands.
The bacteria can invade the body through breaks in the skin and set up a virulent systemic infection, particularly among people with weakened immune systems -
infants, the elderly, the injured or the ill.
Salyers said that that thousands of people die annually of staph infection, but once the death toll was even higher.
Before World War II, more than half of all fatalities in wars came from wounds that were infected by staph or other bacteria, said Salyers. A simple, untreated
scratch on the hand or foot often was enough to set off a raging and lethal infection.
Antibiotics beat staph into the medical background, but starting in the 1980s, antibiotic resistant strains evolved. Drugs that once worked suddenly did not.
Salyers said staph is back and presenting a significant new threat while researchers scramble to learn more about ways to fight it.
``Virtually anything new we find out about staph aureus is an important finding because of its potential as a major public health threat,'' said Salyers.
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On the Net:
American Society for Microbiology: microbe.org
Proceedings of the National Academy of Sciences: eurekalert.org |
