The most common strains of tuberculosis in the most highly infected parts of the world may not be covered by the BCG vaccine.This is the report of Dutch medical researchers speaking Monday at the bi-annual meeting of the Society of General Microbiology (SGM) at the University of East Anglia in the UK.
"We think that in Asia, the former USSR republics and other areas, Beijing type strains of Mycobacterium tuberculosis play a major role in the TB epidemic," says Dr. Dick van Soolingen of the National Institute of Public Health and the Environment in Bilthoven, the Netherlands. "The Beijing strains are also more frequently resistant to the most important drugs used to treat tuberculosis."
The researchers found that in China, over 80% of the circulating strains belonged to the Beijing genotype; in Vietnam 50%, in the former USSR republics up to 60%, and in Japan 60%. In Vietnam, this type of TB was found particularly in young patients, showing that tuberculosis is being actively transmitted.
Using new DNA fingerprinting techniques, medical researchers can now distinguish among tens of thousands of TB strains. The Dutch scientists believe that the Beijing family of bacteria share particular selective advantages, including the ability to gain resistance to the most important drug treatments, such as isoniazid and Streptomycin, and ways to avoid setting off an immune response.
"We are trying to find out whether the current tuberculosis vaccines protect people against these highly infective strains,” says Dr. van Soolingen. "In any case, research should focus on developing new vaccines against the most successful and widespread M. tuberculosis genotypes, including the Beijing type, not just the laboratory strains".
Dr. van Soolingen is Head of the National Mycobacteria Reference Laboratory at the National Institute of Public Health and the Environment (RIVM), Bilthoven, the Netherlands. He gave his conference presentation on Monday on "The role of Mycobacterium tuberculosis Beijing genotype strains in the worldwide tuberculosis epidemic."
(Editor's Note: Full program details of the SGM meeting can be found on the Society for General Microbiology website.)
SGM is the largest microbiology society in Europe, with more than 5,500 members worldwide. The Society provides a common meeting ground for scientists working in research and in fields with applications in microbiology, including medicine, veterinary medicine, pharmaceuticals, industry, agriculture, food, the environment and education.
[Contact: Dr. Dick van Soolingen]
11-Sep-2001
