Association of Characters Among Dissociates from Staphylococcus aureus. ∗

Pinner and Voldrich 1 found that albus “dissociates” of Staphylococcus aureus are of low virulence and produce little or no hemolysin, coagulase or gelatin-liquefying enzyme. Burnet, 2 however, reports that in the absence of CO₂ his albus dissociates produced more hemolysin though less coagulase than his undissociated cultures.

We have studied enzyme-production in 36 paired smooth dissociates from 15 aureus strains (rough variants not studied). Thirteen pairs were obtained by plating 13 stock cultures and selecting the lightest and darkest colony on each plate. Eight pairs were isolated by the same technic from 5 aureus strains aged for 30 days in veal-infusion-broth. Fifteen pairs were isolated from 5-day cultures grown in oxalated Walbum's medium. Relative hemolysin, fibrinolysin, coagulase, gelatin-liquefaction and violet-reaction were determined for each pair.

To determine the association between any 2 characters, the entire population (72 dissociates) was divided as follows: Group AB, cultures in which relatively-high character A is associated with relatively-high character B, when comparison is made between the 2 paired dissociates from the same parent strain. Group ab, cultures in which relatively-non-high A (i. e. equal or relatively-low) and relatively-non-high B are similarly associated. Groups Ab and aB, cultures in which high A is associated with non-high B; or non-high A with high B.