COMPARATIVE PHENOTYPIC CHARACTERISTICS OF STAPHYLOCOCCUS-AUREUS ISOLATES FROM LINE AND NON-LINE ASSOCIATED SEPTICEMIA, CAPD PERITONITIS, BONE JOINT INFECTIONS AND HEALTHY NASAL CARRIERS/

This study compared specific phenotypic and potential virulence charac teristics of Staphylococcus aureus isolates from invasive infections a nd nasal carriers. Three hundred and sixty isolates were studied; 154 from septicaemia (69 line associated, 85 non-line), 79 from continuous ambulatory peritoneal dialysis (CAPD) peritonitis, 64 from bone/joint infections and 64 from healthy nasal carriers. The isolates were test ed for production of enterotoxins (SE) A, B, C or E, toxic shock syndr ome toxin-1 (TSST-1) protein A, and also for lipolytic, proteolytic, f ibrinolytic and haemolytic activities. In addition phage typing, cryst al violet reaction, urease and galactose breakdown were studied. Seven ty-one percent of isolates were enterotoxigenic. Production of SEA was significantly lower amongst the bone/joint isolates. Production of SE B, was lower among the control group compared with CAPD, bone/joint, a nd non-line septicaemia isolates. SEE production was higher among the bone/joint isolates compared with the CAPD and non-line septicaemias a nd production of TSST-1 was significantly higher among nasal isolates compared with isolates causing infection. Almost all of the isolates w ere lipolytic, with highest activity amongst nasal and bone/joint isol ates. Fibrinolytic activity was similar in the five groups of isolates . Proteolytic activity ranged from 35 to 62% of isolates with the lowe st frequency among septicaemia isolates. In all, 80-90% of isolates we re haemolytic, although CAPD isolates were less likely to be haemolyti c. Isolates from the control and CAPD group more frequently belonged t o phage group I. TSST-1 does not appear to be an important requirement for invasive infections, but SEB may be. Proteolysis and intensity of lipolysis appear to be less important in septicaemia, and haemolysis may not be important in CAPD pertonitis.