Growth of group IV mycobacteria on medium containing various saturated and unsaturated fatty acids

Abstract

Seventy-one strains of 15 species of rapidly growing mycobacteria were studied for their susceptibilities to fatty acids with 2 to 20 carbons by the agar dilution method at pH 7.0. Most mycobacteria other than potential pathogens (Mycobacterium fortuitum and Mycobacterium chelonei) were resistant to saturated fatty acids, except for lauric acid (C12:0) (MIC, 6.25 to 25 ,ug/ml) and capric acid (C10:0) (MIC, 50 to 100 ,ug/ml). M. fortuitum and M. chelonei were substantially insusceptible to these fatty acids. Unsaturated fatty acids with 16 to 20 carbons, except for C20:5, were highly toxic to group IV mycobacteria other than M. fortuitum, M. chelonei, Mycobacterium smegmatis, and Mycobacterium phlei, these being highly resistant to all the unsaturated acids, except for C16:1, C18:3, and C20:5. Introduction of double bonds to C16 to C20 fatty acids caused a marked increase in their activities that depended on the increase in the number of double bonds, at least up to three or four. M. fortuitum and M. chelonei were more resistant to the unsaturated fatty acids (particularly to C20:3 and C20:4) than the other group IV mycobacteria.

Susceptibilities of transparent, opaque, and rough colonial variants of Mycobacterium avium complex to various fatty acids

“…It is of interest that M. avium complex showed similar susceptibility to lauric acid as that to oleic and linolenic acids (Table 1), since rapidly growing mycobacteria are considerably more resistant to the former than to the latter two fatty acids (16). This may suggest that, in the case of M. avium complex, the balance of lipophilic and hydrophilic moieties is less important for the exhibition of antimicrobial activity of fatty acids than in the case of rapidly growing mycobacteria.…”

Enzymes for biosynthesis de novo and elongation of fatty acids in mycobacteria grown in host cells: is Mycobacterium leprae competent in fatty acid biosynthesis?

“…As an exogenous source of fatty acid, free fatty acids as such are unlikely to be a suitable source for growth -they are toxic to most mycobacteria (Saito et al, 1984), as well as the host in which they grow. Free fatty acids are scarce in animal tissues although phospholipids and acylglycer01s are present in host cells and may provide a source of fatty acids if M .…”

Effect of ofloxacin combined with Lactobacillus casei against Mycobacterium fortuitum infection induced in mice

“…Previously, we found that LC9018-induced M4s, particularly those induced by multiple injections of the drug, were markedly stimulated in their cellular functions, such as phagocytosis, oxygen metabolism, and interleukin-l-producing ability (18). Therefore, it is thought that LC9018 injections might have resulted in an increase in the rate of uptake for ofloxacin or enhancement of production of certain antimicrobial substances, such as active oxygens (30,31), long chain fatty acids (19), and cationic proteins (11), in host M'Fs. These situations would cause a more prominent activity of ofloxacin in LC9018-induced Mbs than in resident MOs.…”