Epidemic superbug strains evolved from one bacterium: study
Pastor Dale Morgan
Epidemic superbug strains evolved from one bacterium: study*
CHICAGO (AFP) - - The drug-resistant "superbugs" that have cut a swathe
through day care centers, schools, locker rooms and prisons across the
United States in the last five years stem from one rapidly evolving
bacterium, US scientists said Monday.
Scientists studying the genetic make-up of these bugs, which are
resistant to almost all antibiotics, say they are nearly identical
clones that have emerged from a single bacterial strain, which they have
dubbed USA300.
"The USA300 group of strains appears to have extraordinary
transmissibility and fitness," said Frank DeLeo, a researcher with the
National Institute of Allergy and Infectious Diseases (NIAID) in
Hamilton, Montana.
"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."
Most drug-resistant staph infections cause soft-tissue infections such
as boils that are readily treatable, but a skin infection can become a
deadly pneumonia or blood or bone infection in a matter of days if the
patient doesn't get the right drugs.
What's particularly worrying to health authorities is that the MRSA
infections, (methicillin-resistant Staphylococcus aureus) have spread
beyond their traditional hospital setting, seeding an epidemic in the
wider community.
The NIAID scientists studied the DNA of 10 patient samples of the USA300
bacterium taken from individuals treated at different US locations
between 2002 and 2005. They compared the genetic sequences of the bugs
to each other and to USA300 strains used in earlier studies.
The genomes of eight of the 10 patient samples were virtually identical,
indicating they came from a common strain. The remaining two bacteria
were related to the other eight, but more distantly.
The study appears in the Proceedings of the National Academy of Sciences.