Coagulase and hemolysin tests as measures of the pathogenicity of staphylococci

Except in the case of abscesses and certain skin infections, early studies of staphylococci furnished no definite information con-cerning their relation to disease. The term "skin cocci, " used to designate albus varieties found in the skin, was in common use and even to-day persists in such trinomials as "Staphylococcus epidermidis albus. " On the other hand, it was recognized early that cultures from pyogenic foci usually revealed pigmented types. This gave rise to a separation of the species into varieties based on their pigment production. It was generally considered that the white strains were not pathogenic. In this paper we will outline methods which we consider of value for the differen-tiation of pathogenic from non-pathogenic staphylococci. Many authors have shown that Staph. albus, and many of the intermediate-colored varieties, could be derived from Staph. aureus. Pinner and Voldrich (1932) also demonstrated that, of the strains which they examined, the yellow were more path-ogenic than the white. Duran-Reynals (1933) showed that the albus variants differed from aureus parent strains in hem-olysin production and the liquefaction of gelatin. He also found that all the very invasive strains were of the aureus variety while about 82 per cent of his non-invasive strains were of the albus variety. While a number of investigators have studied the pathogenicity of staphylococci, the results have been somewhat confusing as the following survey of the literature will demonstrate