The TDR Tuberculosis Strain Bank: a resource for basic science, tool development and diagnostic services.

BACKGROUND The Special Programme for Research and Training in Tropical Diseases recently launched a Mycobacterium tuberculosis strain bank (TDR-TB Strain Bank). OBJECTIVE To describe the TDR-TB Strain Bank, the characterisation of strains, bank management and the procedure for releasing materials. RESULTS The TDR-TB Strain Bank consists of 229 clinical M. tuberculosis isolates (single-colony derived cultures) plus five mycobacterial reference strains for purposes of identification. These are available as freeze-dried, viable strains or as heat-inactivated bacterial suspensions, quality controlled for purity, viability and authenticity. Isolates originated from diverse geographical settings and were selected for their resistance profiles against first- and second-line drugs. Low and high levels of resistance were determined by the minimum inhibitory concentrations of isoniazid, rifampicin, ethambutol, streptomycin, ofloxacin, kanamycin, capreomycin, ethionamide and para-aminosalicylic acid. Sequencing for drug resistance mutations was performed on the relevant sections of the rpoB, katG, inhA, embB, rpsL, rrs, gyrA and gyrB genes. Typing using lineage-defining loci of mycobacterial interspersed repetitive unit-variable number tandem repeats indicated that the most important genetic lineages were represented. CONCLUSIONS The TDR-TB Strain Bank is a high quality bioresource for basic science, supporting the development of new diagnostics and drug-resistant detection tools and providing reference materials for laboratory quality management programmes.