The evolutionary origin and genetic basis for multi-drug resistance in tuberculosis is reported in a paper published online this week in Nature Genetics. Tuberculosis (TB) is responsible for 1.5 million deaths worldwide each year.
Specific strains of Mycobacterium tuberculosis, the bacteria responsible for TB infection, have acquired resistance to multiple antibiotics and pose a serious health threat in countries with high rates of TB. The spread of multi-drug resistance is driven, in large part, by a group of M. tuberculosis strains called the Beijing lineage.
Thierry Wirth and colleagues analyzed the genetic makeup of 4,987 M. tuberculosis isolates, including complete genomes for 110 strains from 99 countries, to better understand how the Beijing lineage and multi-drug resistance have evolved over time. They found that the population of Beijing lineage M. tuberculosis increased in multiple spikes over the last 200 years, coinciding with the Industrial Revolution and the First World War; followed by a drop coinciding with the rise of antibiotic use in the 1960s. The authors traced the spread across Eurasia, of the two strains most associated with multi-drug resistance, to the early 1990s when the public health system of the former Soviet Union collapsed. Finally, they identified 15 genes that may have contributed to drug resistance in the Beijing lineage.