MOST investigators now regard a virus as the cause of the common cold. This primary infection, however, is usually followed within a few days by a secondary bacterial or purulent infection, which not only prolongs the disease but is largely responsible for such complications as sinusitis, pharyngitis, laryngitis, otitis media, tracheobronchitis and pneumonia.
This important secondary infection is due not to any specific bacterium but to one or more of the bacterial species commonly occurring in the upper respiratory tract. In a recent investigation of this phase of the disease, Kolmer, Bondi and Schillinger1 found that beta hemolytic streptococci of group A, Staphylococcus aureus and various pneumococci (especially Diplococcus pneumoniae of types III, VI, X, XI and XIX) occurred most frequently, although streptococci of the viridans group, gamma streptococci, Staphylococcus albus, Hemophilus influenzae, Klebsiella pneumoniae and organisms of genus Neisseria (especially Neisseria catarrhalis) were found frequently enough to be
KOLMER JA. ACTIVE IMMUNIZATION AGAINST SECONDARY BACTERIAL INFECTIONS OF THE COMMON COLDI. Acquired Immunity in Mice Following Oral and Intra-Abdominal Administration of Stock Polyvalent Bacterial Vaccines. Arch Otolaryngol. 1949;50(6):687–692. doi:10.1001/archotol.1949.00700010702001