Common Colds as a Possible Source of Contagion for Lobar Pneumonia. by Eugenia Valentine

The pneumococcus has been assumed to be one of the causative agents in common colds because of its known pathogenic character and because of its predominance i n the mucous discharge in some cases. As far as we know, determination of the types of pneumococcus encountered in these conditions has not been made except in as far as the Pneumococcus mucosus type was identified on cultural grounds. For this reason, a series of common colds was examined to determine the types of pneumococci present. This was undertaken not so much from the standpoint of determining the. etiological significance of pneumococci in common colds, but rather to determine whether the fixed types occurred. If these were found, common colds would then have to be considered as a source of infection in the spread of lobar pneumonia. By injecting the nasal secretion or sputum into mice, pneumococci were recovered in 37 out of 65 cases of common colds. By direct plating on blood agar, pneumococci were found in 6 additional cases. Of the total 43 cases, the incidence of type or group of pneumococcus recovered was as follows: Group I, 2 cases; Group II, 2 cases; Group HI, 4 cases; Group IV, 35 cases. The cases from which Group II was isolated and one of the Type III cases had been in contact with pneumonia and, with the data available, it is impossible to decide whether they were merely contact carriers or whether the cold was an actual infection by pneumococci due to contact with the pneumonia cases. None of the other cases from which fixed types were isolated had any such contact as far as could be determined. In determining the type, immune horse sera were employed. Con-2;'