Double-blind evaluation of BACTEC and Buddemeyer-type radiorespirometric assays for in vitro screening of antileprosy agents.

Two radiorespirometric assays, the BACTEC 460 and Buddemeyer-type 14CO2 detection systems, were evaluated in a double-blind manner for their ability to discriminate between authentic antileprosy agents and inactive compounds. Freshly harvested, nude-mouse derived Mycobacterium leprae were incubated in axenic media in the presence of coded test solutions prepared in a remote laboratory. Activity was assessed by comparing the rate of 14CO2 evolution from [1-14C]palmitic acid to controls. Breaking the code revealed that both systems demonstrated a dose response to ethionamide, pefloxacin and rifampicin as well as sensitivity to dapsone. Most of the water, ethanol, sucrose, dabsyl chloride and riboflavin negative-control samples failed to effect a significant reduction in radiorespirometric activity. This study confirms the ability of the radiorespirometric assays to function as a primary drug screening system in leprosy.