Robert Koch1 succeeded in isolating the tubercle bacilli in 1882 and later definitely established it as the etiologic factor of the disease by means of animal experimentation. To Theobald Smith2 belongs the credit for differentiating the types of the tubercle bacilli. Most authorities give 1898 as the date of this important observation. However, in 1896, before the Association of American Physicians, Smith mentioned the difference between the two types. His complete work was published in 1898. He designated the tubercle bacilli isolated from man as the human type and those isolated from cattle as the bovine type. His work remains today practically unchanged. These types have definite bacteriologic characteristics and differ widely in many respects. It was not until 1901 that Robert Koch finally admitted the existence of the bovine type, but stated that it was rarely found in human tuberculous patients.
Koch also observed that when the
DESANCTIS AG, REISMAN HA. TUBERCULIN TESTS IN CHILDRENA COMPARATIVE STUDY OF HUMAN AND BOVINE TUBERCULIN. Am J Dis Child. 1927;34(6):1042–1049. doi:10.1001/archpedi.1927.04130240121016