Isolation of Mycobacterium spp. in milk from cows suspected or positive to tuberculosis

RESUMO

This study was performed considering the public health hazards related to the elimination of mycobacteria through milk of dairy cows suspected or positive for tuberculosis presenting no clinical alterations. A total of 780 milk samples from 52 animals, positive or suspected for tuberculosis, according to Stormont's test, were analysed to detect Mycobacterium spp. The samples consisted of 300 ml/cow, collected in the first milking of the day, during 15 days. Frozen samples were sent to the laboratory, inoculated in Löwenstein-Jensen with reduced glicerol (0.5 percent) and Stonebrink media and kept under 37ºC for at least 90 days. The genus of each observed colony was initially confirmed by Ziehl-Neelsen and auramin staining methods. The isolation of Mycobacterium spps was confirmed in 78 (10 percent) samples collected from 19 (36.54 percent) animals. According to thin layer chromatography, time and temperature growth characteristics and colonies aspects, the 19 animals eliminated M. avium (5.26 percent), M. fortuitum (10.52 percent), M. bovis (5.26 percent) and Mycobacterium spp. (78.95 percent)