Lipolytic activity of Staphylococcus aureus strains from cases of human chronic osteomyelitis and other infections

The fatty acid accumulation in a lipid emulsion broth was examined after growth of S. aureus strains incubated for 18 hours at 37 degrees C. Among 40 strains from acute infections and from nasal carriers, Tween 80-positive staphylococci in phage group III caused accumulation of significantly larger amounts of fatty acids than did Tween 80-positive strains in phage group I and Tween 80-negative strains in phage groups I and III. Eight out of 17 S. aureus strains isolated from chronic osteomyelitis gave rise to a low amount of, or total lack of, fatty acids in the lipid broth. Seven of these 8 strains were isolated from cases showing relapse after intensive and prolonged antibiotic treatment. The lipid metabolism of 4 strains showing fatty acid accumulation in lipid broth, ranging from zero to the highest value found in the investigation, was further studied. Results of examination of lipolytic action on trioleinphospholipid and incorporation of 14C-labelled oleic acid suggest that the degree of accumulation of fatty acids in lipid broth depends on variations in the lipolytic activity of the strains rather than on differences in incorporation of the produced fatty acids. The significance of fatty acid accumulation is discussed in relation to the prognosis of chronic staphylococcal osteomyelitis.