Cultivation of Mycobacterium Leprae

Abstract

McKinley and Soule 1 reported the successful cultivation of Mycobacterium leprae, obtained from Puerto Rican lepers, on several culture media. Subsequent reports were made by Soule and McKinley 2 , 3 when their nonchromogenic strain of acid-fast bacilli, believed to be the true Mycobacterium leprae, had been carried through the eighth and sixteenth generations respectively, the latter representing cultivation over a period of 18 months. Experimental protocols were also presented dealing with suggestive experimental lesions produced in 2 species of monkeys. In the cultivation work it was apparent that the leprosy microbe was maintained on artificial media with greater difficulty with each generation or transfer. In the sixteenth generation, so-called, after the organism had been on artificial media for some 18 months, only 2 definitely positive cultures resulted. One of these cultures has been employed in an attempt to ascertain better methods of cultivation.

A logical procedure was to attempt cultivation in embryonic tissue. Minced chick embryo 7 to 11 days old, was washed and suspended in Tyrode's solution. Human embryonic tissue has also been employed, but with less success. In the chick embryo, suspension, growth of the original Mycobacterium leprae has been stimulated. Growth is obtained within 5 days under C02 and O tension as well as under ordinary atmospheric conditions in the incubator. Several additional generations or transfers have been added to the 16 previously reported with this organism. Growth of Mycobacterium leprae has also been obtained with human embryonic spleen tissue suspended in Tyrode's solution, but this tissue is more difficult to obtain and is no longer employed in our routine culture work. With the young chick embryo tissue medium we are now able to cultivate, apparently indefinitely, this strain of Mycobacterium leprae.