Pyruvic acid egg medium for tubercle bacilli.

Sputum culture for tubercle bacilli on a solid egg medium containing glycerol was compared with culture on a similar medium containing pyruvic acid and no glycerol. Tubercle bacilli from the sputum of five out of 99 patients grew on pyruvic acid medium but not on glycerol medium. The addition of pyruvic acid is therefore essential when an egg medium is used for the cultural diagnosis of tuberculosis. There was no clear relation between catalase activity or isoniazid resistance and preferential growth of tubercle bacilli on pyruvic acid medium.