Modified rapid radiometric method for detection of Mycobacterium tuberculosis from sputum samples

A modified, simple and radiometric method for early detection of M. tuberculosis from sputum samples has been developed using a biphasic vial system for detection of 14C-CO2 produced by the metabolism of 14C-U-acetate on glycerol-free Lowenstein-Jensen medium (LJM). Of the 84 smear positive sputum samples examined, 85.7% and 86.9% were scored positive by radiometric and visual methods respectively. The detection rates at 1st, 2nd and 3rd week of the test were 53.3%, 60.7% and 82.1% by radiometry and 1.2%, 11.9% and 54.8% by visual methods respectively. The mean detection time was 10.7 days by the radiometric and 21.0 days by the visual method. An average replication time of primary culture from 54 sputum samples was 25.58 +/- 6.92 h (range 10.0-39.1 h).