The colonial microtexture of human mycobacterial strains isolated in Burma

Sixteen strains of Mycobacterium tuberculosis isolated in Burma were investigated for microcolonial texture using the thin section technique developed at the WHO Collaborating Centre in Prague. The strains were grown in deep (Sula's liquid medium) and surface cultures (Loevenstein-Jensen medium). Their colonies killed by 10% formol were embedded in 2% agar and paraffin, cut by a Reichert microtome and stained by the Ziehl-Neelsen technique. According to the surface texture and deep growth pattern, the Burmese strains were divided in three different groups. The European type was characterized by a growth strictly confined to the surface of the Loevenstein-Jensen medium, the African type by combined surface and subsurface growth, and the Burmese type not seen in Europe and Africa by non acid-fast granular and acid-fast colonies with distinct formation of strongly acid-fast cords both in surface and subsurface growth.