A genomic analysis of the tuberculosis bacterium in a Russian population reveals that the microbe is not only evolving resistance to multiple drugs, but also retaining its ability to survive and spread.

Francis Drobniewski at Queen Mary University of London and his colleagues sequenced the genomes of 1,000 Mycobacterium tuberculosis isolates from people in western Russia. Two-thirds of the isolates belonged to a lineage that first emerged in Asia and is prone to developing drug resistance. More than 60% of the isolates had drug-resistance mutations. Such mutations typically hinder bacteria's ability to spread, but the team found new 'compensatory' mutations that might maintain transmissibility in more than 400 isolates with resistance to the antibiotic rifampicin.

The findings suggest that biological factors, and not just weak public-health measures, are behind the high incidence of tuberculosis in Russia.

Nature Genetics http://dx.doi.org/10.1038/ng.2878 (2014)