Diplococcus pneumoniae was classified as types I, II and III and group IV prior to 1929, when Cooper1 and her co-workers separated group IV into twenty-nine additional types. At the present time the recognized types are designated by the Roman numerals I to XXXII, inclusive. A number of important studies of the pneumococcus in ocular diseases have appeared in the literature, but a study of the types included in group IV has not been reported. Römer2 unsuccessfully attempted to treat ulcus serpens corneae with antiserums, but, since approximately 75 per cent of the pneumococci which cause ophthalmic disease are group IV organisms, specific serum reactions were not to be expected. Consequently, it appeared practical to undertake an investigation of the organisms in this heterogenous group.
In 1917 Avery and his co-workers3 studied the relative incidence and mortality for the four original types of pneumococci in pneumonia (table
NEWMAN EW. DIPLOCOCCUS PNEUMONIAE AND STREPTOCOCCUS VIRIDANS IN OCULAR DISEASESREPORT OF ONE HUNDRED CASES. Arch Ophthalmol. 1938;19(1):95–102. doi:10.1001/archopht.1938.00850130107011