Scientists map origin of MRSA, technology could help understanding of other diseases

"Scientists have found a way to track minutely-differing strains of the 'superbug' MRSA [methicillin-resistant Staphylococcus aureus] as they spread between people and across the globe, a finding that could aid efforts to control the deadly bacteria," Reuters/ABC News reports (Kelland, 1/21).   

"Although MRSA is usually not serious in healthy people, it can cause serious complications, including organ failure and death, if it enters the bloodstream," HealthDay/Business Week writes. Of particular concern is the fact that MRSA is a common infection in hospitals, where patient populations can be more vulnerable to the strain (1/21).

In a study published Thursday in the journal Science, an international team of researchers describes how they used in-depth gene sequencing to compare the genomes of MRSA samples collected from patients around the world in hopes of better understanding how the bacteria spreads, Reuters/ABC News reports (Kelland, 1/21).   

"They created genetic blueprints of 63 samples of MRSA collected around the world between 1982 and 2003, and tracked even minor DNA variation to trace how one common strain - called ST239 - spread, from continent to continent and within one hospital in Thailand," the Associated Press/San Francisco Chronicle writes. "The resulting family tree suggests this MRSA strain originated in Europe in the 1960s, just as antibiotics were being widely used. It spread to South America and became dominant in parts of Asia" (Neergaard, 1/21).

The study also revealed that of the "20 isolates collected in a hospital in Thailand over a five-month period … most of those infections originated outside of the hospital from bacteria brought in by patients, health care workers or visitors, rather than being passed from patient to patient inside the hospital … the researchers also found evidence of a spread among five patients in adjacent hospital wards over a two-week period," Science News writes (Hesman Saey, 1/21).

The U.K. Press Association writes, "Senior author Dr. Stephen Bentley of the Sanger Institute said the ability to differentiate between isolates is important for developing public-health programs to reduce the number of people infected with and sickened by MRSA." Co-author Sharon Peacock, of Cambridge University, said, "The implications for public health are clear: this technology represents the potential to trace transmission pathways of MRSA more definitively so that interventions or treatments can be targeted with precision and according to need" (Ubelacker, 1/21).

Scientific American examines how the new technology to compare bacterial genomes has become faster and cheaper over the past decade, and how such technologies are being used "to study the organisms at work in pneumonia, diarrhea, tuberculosis and meningitis" (Harmon, 1/21).