A biologic classification of pneumococci into four groups has been established by the work of Dochez, Gillespie, Cole and Avery. A study of type IV, which has been considered a heterogeneous series of independent strains, was undertaken at The Presbyterian Hospital in connection with an investigation of post-operative pneumonia, in which the type IV pneumococci have been found to be an important etiological factor. Many of the strains examined have been obtained, by mouse passage from sputum or saliva of surgical cases before operation and may be considered normal mouth inhabitants. The others have been recovered from the sputum of post-operative pneumonia cases, of pneumonia cases in the medical wards of the hospital, of bronchitis cases, from lung cultures at autopsies, from blood cultures, from spinal fluid, from chest fluid and from abscess cultures. All the strains when isolated failed to react with serum of types I and II.


Read before American Association of Immunologists, April 6, 1917.

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