Phage Group, Lipase Activity and Protein a Content of Staphylococcus Aureus Strains from Cases of Chronic Osteomyelitis

61 patients with chronic osteomyelitis were admitted to the University Hospital of Lund during a 7-year period. Positive cultures were obtained from 59 cases, all of them showing growth of Staphylococcus aureus. 50 strains were phage-typed, 40 strains tested for lipase activity, and 16 strains investigated on protein A content and α-toxin production. The osteomyelitic strains were compared in these respects and regarding antibiotic resistance patterns with other staphylococcal strains from routine diagnostic work. 13/15 strains from cases of hematogenous osteomyelitis belonged to phage groups I and II; none belonged to group III. This distribution differed significantly from posttraumatic osteomyelitic strains and from strains isolated from cases of septicemia. 90% of the osteomyelitic strains were lipase-positive and did not differ from unselected strains. Among the unselected control strains lipase activity in phage group III was significantly less frequent than in phage groups I and II. All 16 osteomyelitic strains tested were protein A-positive. The incidence of α-toxin production in osteomyelitic strains did not differ from that in the control strains.