Capsule Production and Virulence Among Strains of Staphylococcus Aureus

In 1956, just after Price and Kneelandl first reported the occurrence of a specific capsular reaction in a strain of mucoid S. aureus isolated after egg passage of a throat isolate with an A strain of influenza virus, we were searching about for an area of endeavor that might interest us. Their initial report was followed by a second one in which they seemed to downgrade the importance of their finding by reporting what they interpreted as a lack of specificity, owing to the fact that all of 39 isolates of S. aureus from clinical material exhibited specific capsular reactions with a single antiserum. We could not agree with their conclusion; this proved to be the stimulus that awakened our interest in the occurrence of encapsulation and its significance among strains of S. aureus. Our first efforts in the field were concerned with the isolation of mucoid variants of S. aureus; we employed the technique of Bigger and colleagues.:: They cultivated staphylococci in broth that contained a fermentable carbohy-drate, and maintained the cultures in this environment for up to two months.