CHAPTER XVI - PNEUMOCOCCUS: PNEUMONIA

Abstract

Pneumococci are Gram-positive cocci, exhibiting a marked tendency to arrangement as lanceolate diplococci and growing poorly on ordinary media; they usually ferment insulin, are soluble in bile, and are frequent pathogens in man. In man, the pneumococcus is found as a commensal, being present in the mouth and naso-pharynx. It is also responsible for many diverse conditions, such as primary pneumonia, broncho-pneumonia, empyema, otitis media, meningitis, arthritis, endocarditis and primary peritonitis of children. Pneumonia tends to run a characteristic course that is readily recognized by the clinician. The severity of the infection is dependent on the type of the infecting pneumococcus and the age and general condition of the patient; the mortality rate is highest in patients over 35, while type II and III pneumonias are fatal than type I infections. Antipneumococcal serum is prepared by the intravenous injection of young killed cocci into the horse; after a prolonged period of immunization, potent serum is usually obtained. The antibody is concentrated, but this process is rendered difficult by the fact that the antibody is associated with the water-insoluble protein.