Enterotoxigenicity of Staphylococcus aureus strains from clinical isolates

The enterotoxigenicity of 208 strains of Staphylococcus aureus isolated from clinical specimens and four strains isolated from food was investigated. All strains were examined for production of enterotoxins A, B, C, D, and E in cellophane-over-agar cultures using a modified optimum-sensitivity-plate method. Strains from systemic infections were also examined for production of toxic-shock toxin. The overall frequency of enterotoxigenic strains among the clinical isolates was 42%. Enterotoxin A was the predominant enterotoxin found among positive strains (45/88). Enterotoxins B to E were found in decreasing order of frequency. Twenty-three strains produced two enterotoxins and one strain three toxins. A significant association was observed between multi-resistance of strains (defined as resistance against penicillin and at least two other antibiotics) and enterotoxin B production. Strains from phage groups I and III produced predominantly enterotoxin A. Four of the five strains producing toxic shock toxin belonged to phage group I; one was not classifiable.