Coagulase and Hemolysin Tests as Measures of the Pathogenicity of Staphylococci

Abstract

Except in the case of abscesses and certain skin infections, early studies of staphylococci furnished no definite information concerning their relation to disease. The term "skin cocci," used to designate albus varieties found in the skin, was in common use and even today 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 differentiation 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 pathogenic than the white. Duran-Reynals (1933) showed that the albus variants differed from aureus parent strains in hemolysin 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.

Crystal Violet Agar as a Differential Medium for Staphylococci

“…Three of the strains with doubtful violet reactions were included in this group but they had no effect on the rabbits and should, therefore, be considered as white strains. Confirming the work reported in the previous paper (Chapman et al (1934)), most of the killed cultures of hemolytic non-coagulating albus strains had no apparent effect on rabbits.…”

“…In comparing the violet reactions of staphylococcal strains with their pathogenicity for rabbits, experiments were undertaken using filtered killed suspensions in place of live unfiltered cultures. It was hoped by this method to secure more clear cut results than had been obtained previously (Chapman et al, 1934).…”

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In a previous paper Chapman, Berens, Peters and Curcio (1934) showed that staphylococci could be differentiated on the basis of their hemolysis and coagulase reactions. It was further shown that a critical interpretation of the hemolysis test depended upon an accurate knowledge of the pigment production of the strain.

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Fibrinolytic, Anticoagulating and Plasma-Clotting Properties of Staphylococci

“…A review of this subject is given in the article by . The question, whether the plasma-clotting factor of staphylococci might be of significance in the development and course of staphylococcus infections was recently discussed by Chapman, Berens, Peters and Curcio (1934), by Menkin and Walston (1935) and by Pioan (1935). * It is of interest, therefore, to determine whether or not the staphylococcus coagulant may be produced in natural staphylococcus infections.…”

Staphylococcus aureusin the milk of nursing mothers and the alimentary canal of their infants: A report to the Medical Research Council

“…albus. Many observers, including von Daranyi and Gross (quoted by Fisher, 1936), regard this reaction as evidence of pathogenicity, and some, like Kemkes (quoted by Fisher, 1936) and Chapman, Berens, Peters & Curcio (1934) accept it also as an index of the virulence of the coccus. The value of the test as a measure of virulence or pathogenicity may be prejudiced by the fact that the clotting can be caused by two separate agencies: a free coagulase and the direct action of the living cocci.…”