Investigation of the in vitro activity of streptomycin against Mycobacterium tuberculosis

Streptomycin was the first antibiotic used against Mycobacterium tuberculosis. It was used for years in monotherapy regimens, leading to the emergence of resistance; therefore, its use gradually waned. Given the resistance rates detected with current antituberculosis drugs, the use of streptomycin has gained renewed interest. The mechanism of action of streptomycin is inhibition of protein synthesis of mycobacteria in the ribosome. Resistance emerges when mutations appear in genes encoding 16S rRNA and protein S12. The activity of streptomycin against 1,496 M. tuberculosis strains was investigated; 1,186 and 196 strains corresponded to pulmonary and extrapulmonary specimens, respectively. For 114 strains, the source was not indicated. Initially, the BACTEC 460 TB system was used for antibiotic susceptibility testing. Since 1996, the ESP II system was used. The strains ATCC27294 (sensitive to streptomycin, rifampin, ethambutol, and isoniazid) and ATCC35820 (resistant to streptomycin) were used as controls. An overall resistance rate of 2.2% was obtained. In all cases secondary resistance was observed. Multiresistance was observed in 23 strains.