Preliminary results of investigations on the occurrence of Streptomycin and hydrazid resistant strains of M. tuberculosis from animal sources

Abstract

Concerning to the existence of naturally resistant strains of M. tuberculosis isolated from animals never treated with streptomycin or hydrazide, the study of 38 strains (27 bovines and 11 dogs) gave negative results in all those of bovine origin and in 9 of canine origin. One strain from dog grew up in presence of 50 mcg of streptomycin and other gave positive cultures in presence of 500 mcg of streptomycin and 100 mcg of hydrazide, being considered both resistant. We think from our results that the occurrence of naturally streptomycin or hydrazide resistant strains of M. tuberculosis in not treated animals, is not a common fact. Concerning to the resistant strains found in dogs, we prefer to admit a contamination of those animals by resistant strains, possibly of human origin. We call attention to the fact that animals harbouring resistant strains may have an important role in transmission of these strains among animals and man.