Use of Dubos Medium for Culture of M. tuberculosis from Sputum

The use of a mild reagent (2.5% solution of ammonium carbonate) for homogenization and concentration of tuberculous sputa and the addition of penicillin (0.05 to 2 units per ml) to the culture medium permits the successful application of Dubos medium to the routine culture of M. tuberculosis from sputum. Of 400 examined sputa, 34 (8.5%) were positive by culture method and negative by microscopic examination. The advantage of the culture method is obvious. As compared with other culture methods, the use of Dubos media is inexpensive, easily learned by an average technician, suitable for daily examination of a large number of specimens, and what is more, offers the advantage of a rapid (within 8 to 15 days) culture diagnosis of sputa containing relatively small numbers of M. tuberculosis.