Abstract
While studying the bacterial flora in the exudate in a case of chronic empyema of tuberculous origin 2 organisms were found which performed a function which neither could accomplish alone. One was a double-zoned Staphylococcus aureus. The other was a nonhemolytic diphtheroid bacillus.
On blood agar plates the colony of the double-zoned Staphylococcus aureus has a narrow zone of clear hemolysis about twice the diameter of the colony immediately around it and a wide zone of partial hemolysis about 8 times the diameter of the colony. Among the anaerobic bacteria this double zone is seen about certain strains of C. welchii while non-hemolytic strains of C. welchii have the outer zone only. The nature of these 2 changes in the hemoglobin is not fully understood.
While working with the culture from the pleural exudate it so happened that when the colonies were fished from the original blood agar culture to a fresh plate the diphtheroid bacillus and the double-zoned Staphylococcus were streaked side by side. After incubation, this plate showed that on the side toward the diphtheroid bacillus the outer zones of the Staphylococcus colonies were completely hemolyzed over an area very evidently under the influence of some diffusible substance or physical force emanating from the colonies of the diphtheroid bacillus. Immediately around these colonies no change in the red cells was visible but over an area 8 or 10 times the diameter of the colony some chemical substance or physical force was operating which, whenever it came in contact with the outer zone of partial hemolysis from the Staphylococcus colonies, completed the hemolytic process not only of laking the red cells but of changing the color from red to yellow. In order that this effect might be brought out more clearly a design was made on another plate by alternately dotting with the 2 cultures.
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