In-the-Wild Superbug Strains All Evolved From Single Rapidly-Mutating Bacterium

Friday, August 08, 2008 by: David Gutierrez, staff writer
Tags: superbugs, health news, Natural News

(NaturalNews) All the major strains of "superbug" methicillin-resistant Staphylococcus aureus (MRSA) that have been alarming public health officials evolved from a single strain within the last few years, according to a study conducted by researchers with the National Institute of Allergy and Infectious Diseases (NIAID) in Hamilton, Montana, and published in the Proceedings of the National Academy of Sciences.

MRSA is a skin infection that is resistant to most first-line antibiotics. While staph infections, including MRSA, tend to be of no major concern if treated promptly, MRSA's antibiotic resistance makes it more likely to go untreated and progress into potentially fatal complications such as pneumonia, blood or bone infections. In recent years, MRSA has spread from its traditional hospital setting to other institutions such as schools, prisons and nursing homes, raising fears of a public health crisis.

"Staph has been a scourge of mankind forever; it is the leading cause of skin and soft tissue infections and respiratory infections worldwide," lead researcher Frank DeLeo said.

Researchers examined 10 samples of MRSA taken from patients across the United States between 2002 and 2005. They compared the genetic sequences of these samples with each other and with the sequences of an earlier strain called USA300.

The genomes of eight of the 10 strains were almost identical, while the other two were more distantly related. This suggests that nearly all MRSA infections emerge from an initial ancestral USA300.

"The USA300 group of strains appears to have extraordinary transmissibility and fitness," DeLeo said. "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."

The genetic codes of Staph bacteria are relatively stable compared to many viruses such as HIV or hepatitis C, DeLeo said, meaning that new strains emerge fairly slowly. But because the bacteria are prone to pick up genes from other kinds of bacteria and even viruses, they are more likely to generate toxins that make infections more dangerous.