Expanded tracking of a Beijing Mycobacterium tuberculosis strain involved in an outbreak in France

Advanced epidemiological surveillance supported on genomic epidemiology were necessary to fully describe a Mycobacterium tuberculosis Beijing strain (ARA, Auvergne-Rhône-Alpes region) outbreak in France. The index case was a migrant from Cape Verde with a two-year history of tuberculosis, high bacillary load, and frequent trips within France and to Portugal. We designed an ARA-specific PCR to complete the tracking of this outbreak strain. The ARA-specific PCR was applied on 160 Beijing isolates from independent cases from the Auvergne-Rhône-Alpes region and on 25 cases from Cape Verde migrants in the Île-de-France region. No more cases were found, indicating that the previous surveillance had been exhaustive enough to capture the whole dimension of the outbreak in France. Next, we performed a cross-border surveillance, applying the PCR on 38 Beijing isolates in Portuthe gal. In all four cases (all migrants from Cape Verde) the ARA strain was identified. Whole genome sequences analysis of all ARA isolates representatives indicated a diversification of the strain into two variants present one in France and one in Portugal.