Despite penicillin and the dozens of antibiotics that followed it, streptococcus bacteria have remained a major threat to health throughout the world. The reason: the superb evolutionary skills of this pathogen to rapidly alter its genetic makeup. In a landmark paper published this week in Science, scientists from Rockefeller University and the Sanger Institute have used full genome sequencing to identify the precise steps in the molecular evolution of Streptococcus pneumoniae. Their research shows the changes the genome of this bacterium has undergone in time and during its massive geographic spread over the globe.
According to the World Health Organization, fatal pneumococcal disease mostly among children from underdeveloped countries claims an estimated 4 million casualties per year. Humans are not only the primary targets of pneumococcal disease but also represent the major and possibly the only ecological reservoir on our planet for this bacterial species, which colonizes the nasopharynx of preschool age children.
The researchers, led by the Sanger Institute's Stephen D. Bentley, used high resolution genome sequencing on clinical isolates of S. pneumoniae provided by a number of collaborating laboratories, including the Laboratory of Microbiology and Infectious Diseases at Rockefeller University, headed by Alexander Tomasz. With data available for the date, geographic site and infection site of these isolates, Bentley and colleagues were able to produce a roadmap for the evolution of a major multidrug resistant clones of pneumococci known as the PMEN clone 1, sequence type 81.
The scientists pinpointed the probable date of birth, 1970, and the likely birthplace, Europe, of this extremely successful multidrug resistant clone. The clone then spread to South and North America, South Africa and Asia. The presence of this clone in 12 New York City hospitals was demonstrated by Tomasz's group in 2001. Perhaps mor
|Contact: Joseph Bonner|