An in vitro test using cholesterol metabolism of macrophages to determine drug sensitivity and resistance of Mycobacterium leprae.

Macrophages that have ingested live Mycobacterium leprae show a preferential accumulation of cholesterol ester. Such an accumulation is not seen, on the ingestion of dead bacteria. Among the macrophages that ingest live Mycobacterium leprae, the presence of dapsone or rifampicin prevents largely the alteration in the anticipated increase in the cholesterol ester indicating the sensitivity of the bacteria to the drug. In the small number of relapsed patients, the presence of dapsone did not reduce the cholesterol ester increase, suggesting that the Mycobacterium leprae present are either resistant or escaped detection. The method provides a rapid drug screening system for anti-Mycobacterium leprae activity of known and unknown compounds.