THE VIABILITY OF THE PNEUMOCOCCUS AFTER DRYING: A STUDY OF ONE OF THE FACTORS IN PNEUMONIC INFECTION.
I. In moist sputum kept in the dark at room temperatures the average life of the pneumococcus is eleven days, though considerable variations may be noted in different specimens of sputum. In the same sputum kept at o degrees C. the average life of the organism is thirty-five days. In sputum kept at room temperature and in a strong light the pneumococcus lives less than five days. II. In dried sputum (a) in the dark the pneumococcus lives on an average thirty-five days; (b) in diffuse light, thirty days; (c) in sunlight, less than four hours. III. In powdered sputum even when kept in the dark the death of the pneumococcus takes place in from one to four hours. When exposed to sunlight death occurs within an hour. IV. No important differences were noted in the life of the pneumococcus when dried on glass, tin, or wood. On cloth the life was usually slightly longer than on non-absorbing surfaces. V. Sprayed sputum particles remain in suspension for twenty-four hours, but all masses of a size sufficient to contain bacteria settle at a rate of about 40 cm. per hour. VI. When sputum containing pneumococci is sprayed the organisms rarely survive for more than an hour, and often die in less time. The substance upon which the particles fall makes but little difference in the life of the organism. On cloth a slight prolongation is occasionally noted, due perhaps to the slow drying. VII. The mucus of the sputum exerts a destructive action on the pneumococcus. VIII. Exposure of bacterial spray to sunlight while in suspension results in the destruction of the pneumococcus within half an hour.
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A Study from the Department of Pathology, Columbia University, under a Grant from the Commission for the Investigation of Acute Respiratory Diseases, of the Department of Health of the City of New York.