An injection of 104 viable type 19 Streptococcus pneumonia into the middle ear of guinea pigs results in the onset of acute otitis media. However, a 3-day intramuscular injection of antibiotics (40mg ABPC, 2mg DKB) completely inhibits the onset of otitis media, and no fluid is observed in the middle ear, even after the injection of 106 viable cells. On the other hand, when an injection of 104-106 viable cells and the same antibiotics were given to 6 guinea pigs that had been systemically sensitized to formalin-treated Streptococcus pneumoniae, sterile serous fluid was observed in the middle ear of all cases. Judging from the results of immunohistological examination using immunofluorescence, the mechanism for this result was thought to be type III allergy.
