During preliminary investigations in the present epidemic, the isolation of B. influenzae from sputum was found to be a difficult task when the usual routine procedure of plating on human blood agar was followed. The difficulty in isolating by this method is due to the fact that other organisms, such as pneumococci, staphylococci and Micrococcus catarrhalis, tend to obscure the colonies of influenza bacilli and overgrow them. Therefore it can be readily seen that in most instances the element of chance in isolating the influenza bacillus by blood agar plates alone is great and the whole procedure uncertain.
In 1903, Cantani1 reported the interesting observation that bile did not destroy the virulence of influenza bacilli. Cultures of these organisms and bile simultaneously introduced into the peritoneum of guinea-pigs invariably killed the animals. It occurred to me to use bile or bile salts because of the dissolving action of bile
ECKER EE. AN APPARENTLY PRACTICAL METHOD FOR THE ISOLATION OF PFEIFFER'S BACILLUS FROM SPUTUM. JAMA. 1918;71(18):1482. doi:10.1001/jama.1918.26020440007009d