Sphingomyelinase activity of Staphylococcus aureus strains from recurrent furunculosis and other infections.

The sphingomyelinase (beta-hemolysin) production by 180 Staphylococcus aureus strains was determined in a qualitative enzyme impression test (EIT) and all but 4 strains in a quantitative enzyme assay test (EAT) using 14C-sphingomyelin as test substrates. A total of 59 strains (33%) were positive for enzyme production in the EIT. The highest frequency was found in strains isolated from recurrent furunculosis (45%) as compared with strains from chronic osteomyelitis, tropical pyomyositis and healthy nasal carriers (18, 8 and 19%, respectively). High producers of sphingomyelinase in EAT were mostly found among furunculosis strains, phage type 55 and/or 71. The furunculosis strains lysed by phages 3A and/or 3C mostly had a low sphingomyelinase production. In 3 families, high- and low- producing strains of the same phage group were isolated from 2 different members of the same family. The high-producing strains caused more intense skin lesions.