Background A bilayered medium (BLM) seemed to indicate a rapid recovery time from Mycobacterium tuberculosis (M. tuberculosis) for the patients in question, namely, 48 hours. Method Sputum specimens collected from 112 patients with clinically suspected pulmonary tuberculosis were subjected to Ziehl-Neelsen staining and inoculation on Lowenstein-Jensen medium (LJM) and BLM. Results BLM grew all the 36 (100%) smear positive samples, while LJM grew only 20 (55.5%). On the first 2 days of incubation, BLM grew M. tuberculosis colonies in 14 specimens and in 36 specimens after 3 to 6 days. From the seventh day until the end of the incubation period, BLM grew M. tuberculosis in only 9 specimens. The mean (SD) time for detection on BLM was 6 (5) days, whereas on LJM, it was 22 (12) days. Conclusions BLM is more sensitive than LJM in positive and negative smears. It was also much faster than other methods in detecting the presence of M. tuberculosis.
