A new method of determining the sensitivity of M. tuberculosis to chemotherapeutic agents.

Many methods are available for determining the sensitivity of M. tuberculosis to various chemotherapeutic agents. These may be divided broadly into three groups. In the first group the streptomycin is incorporated into solid media, such as that of Herrold (1931) or of Lowenstein (1930) and Jensen (1932) (Pyle, 1947; Johnson, 1950; Youmans, Ibrahim, Sweany, and Sweany, 1950; Tinne and Henderson, 1950; Wildy, 1951). The techniques included in the second group necessitate the use of liquid semi-synthetic media such as that of Proskauer and Beck (1894) as modified by Youmans (1944), or the medium of Long (1919) as modified by Dubos (1945) and Dubos and Davis (1946) (Medical Research Council report, 1948; Vollum, 1952). The methods of the third group of workers have not gained much popularity, as they present numerous technical difficulties. Emmart (1945) used chick embryos, while Cummings and Drummond (1949) recommended a slide culture technique. Only those in the first group can be considered practicable for use in the laboratory where there is a shortage of technical staff. The method to be described (modified from Beemer, 1951) is designed to fulfil this need.