A STUDY OF ATYPICAL TYPE II PNEUMOCOCCI

1. At least twelve subgroups of atypical Type II pneumococcus may be recognized by specific agglutination reactions. They have been designated Subgroups IIa, IIb, IIc, IId, IIe, IIf, IIg, IIh, IIj, IIk, IIl, and IIm. 2. These subgroups have an incidence of 11 per cent in lobar pneumonia, and of 18 per cent in normal mouths. 3. Certain groups, IIb, IIc, IIf, and IIm, occur in normal mouths. 4. Subgroups IIa and IIh are met with largely in connection with disease. 5. The mortality of acute lobar pneumonia due to these atypical Type II pneumococci is fairly high—32 per cent.