In-vitro activities of aminoglycoside-aminocyclitols against mycobacteria

Aminoglycoside-aminocyclitols including streptomycin, kanamycin, capreomycin and amikacin showed considerable activity against Mycobacterium tuberculosis, with MICs well below their Cmax and relatively low MBC/MIC ratios. Kanamycin, capreomycin and amikacin remained highly active against 'resistant' and 'multidrug-resistant' M. tuberculosis isolates except for some 'multidrug-resistant' isolates which showed complete cross-resistance between streptomycin and the selected 2-deoxystreptamines. Gentamicin displayed anti-tuberculous activity but was bacteriostatic only. Non-tuberculosis mycobacteria, in particular Mycobacterium chelonae and Mycobacterium avium-intracellulare, were more resistant than M. tuberculosis. Amikacin was inhibitory against Mycobacterium kanasii, Mycobacterium scrofulaceum and Mycobacterium fortuitum, but was bactericidal against M. scrofulaceum only. Kanamycin was also bactericidal against M. scrofulaceum. Growth of M. fortuitum was inhibited by amikacin and neomycin which was also inhibitory against M. tuberculosis and M. scrofulaceum. Although the application of neomycin has been limited by its high toxicity, this study suggested that this drug might be useful as a topical agent for cutaneous infections by M. fortuitum.