CONTROL OF FREE FATTY ACIDS IN HUMAN SURFACE LIPIDS BY <em>CORYNEBACTERIUM ACNES</em>.

Aerobic bacteria were excluded as a major source of lipases when it was found, in a previous study, that their virtual eradication by topical neomycin did not lower the free fatty acids (FFA) in scalp lipids. We now report the reciprocal experiment in which an oral tetracycline was used to suppress the anaerobic organisms. Nine healthy adults received 600 mgm of demethylchlortetracycline (DMCT) daily for 6 weeks. During this time we followed the composition of scalp lipid by thin layer chromatography and the densities of C. acnes, aerobes and yeasts on scalp and forehead. Six subjects had high initial levels of C. acnes. In these the FFA fell from 43% to 23% with a more than 99% reduction in the density of C. acnes. In three who initially had insignificant quantities of C. acnes the FFA were at the start only 25% and did not decline with treatment. The density of the aerobic population was not affected by DMCT owing to development of resistance. Yeasts were also unaffected. The finding that the FFA were proportional to the level of C. acnes suggests that these organisms are the chief source of lipolytic enzymes. The FFA levels began to decline earlier than the density of C. acnes. This might be explained either by enzyme inhibition or by bacteriostatic effect. [ABSTRACT FROM AUTHOR]