Mycobacterial lipids in infected tissue samples.

Mycobacteria synthesize characteristic lipids which can readily be distinguished from those synthesized by the host cells which they infect during pathogenesis. This fact can be exploited to provide information about mycobacteria growing in infected tissue samples: (a) qualitative analysis of lipid extracts from lepromatous leprosy skin biopsies reveals the presence of several mycobacterial lipids including an M. leprae-specific glycolipid, phthiocerol dimycocerosate and mycolic acids; (b) quantitative analysis shows that the amount of mycobacterial lipids present in lepromatous lesions is much greater than that expected on the basis of the number of acid-fast bacilli present; (c) incorporation of 14C-acetate into cell wall mycolic acids can be used to monitor the growth of intracellular mycobacteria.