Geographic variation of the predictive values of genomic mutations associated with streptomycin resistance in Mycobacterium tuberculosis.

Specific mutations associated with resistance to streptomycin (SM) in Mycobacterium tuberculosis suggest themselves for its rapid prediction. However, as with any diagnostic test, their predictive values are dependent on their prevalences. In this report, SM resistance associated mutations in the rrs and rpsL genes of 25 SM resistant isolates from Germany and 25 SM resistant isolates from Sierra Leone were characterized and compared. Mutations in the rrs gene were infrequent in isolates from both localities (20% and 12%, respectively) and thus of limited predictive values. In contrast, rpsL mutations were found in 48% of the German isolates but only in 24% of the isolates from Sierra Leone. It is concluded that the predictive values of mutations in this gene may vary significantly with the origin of the samples under investigation.