Persistence of Inspired H. influenzae in Mice *

Since Pittman,2 in 1931, showed that rough and smooth strains of H. influenzae could be easily distinguished and that the encapsulated strains might be serologically differentiated into six groups, comparatively little work has been done with these organisms. It has been noted that H. influenzae and the pneumococcus are frequently present in the nose and throat in cases of acute pneumococcus pneumonia."' At present, however, the exact significance of the association of H. influenzae with acute pneumococcus pneumonia is uncertain. Many organisms, including the pneumococcus, are known to live on mucous membranes of the upper respiratory tract without producing disease. An understanding of the epidemiology of pneumonia necessitates a knowledge of the capacity of H. influenzae to invade the tissues, once these organisms have gained entrance to the lower respiratory tract. In the present paper the spray method was used as a test of the native power of the six serological types of H. influenzae to gain access to the deeper tissues following implantation of the inhaled organisms on the mucous membrane of the respiratory tract of mice. Since pneumococci are known to persist for longer periods of time in the lungs of mice intoxicated with alcohol, the present experiments were carried out in duplicate series of normal and narcotized mice.