Effect of penicillin on polyp formation in acute otitis media

Hypothesis/Background: The mucoperiosteal lining of the middle ear cavity is subject to radical changes during and after acute infection. Among these is the formation of mucosal polyps. Previous studies on experimental acute otitis media have shown a marked impact of penicillin on mucosal histomorphology. This study reports on the effect of penicillin administration on polyp formation. Methods: The mucosa of 75 rat middle ears in a model of acute otitis media was examined. Whole-mount and section preparations from 25 normal ears, 25 ears inoculated with Streptococcus pneumoniae, and 25 inoculated, penicillin-treated ears were inspected for number, size, anatomic localization, and histopathologic morphology of occurring polyps. Results: The total number of polyps was unaffected by penicillin administration, although polyps occurred in fewer ears. The polyps from treated ears tended to be smaller and stalky, appeared later in the timespan covered, and often were located around the tubal orifice. Histopathologic morphology of polyp base, core, and epithelial covering was otherwise unaffected by penicillin. Conclusions: Administration of penicillin has inconspicuous effect on the formation of polyps in experimental otitis media caused by S. pneumoniae in contrast to a marked impact on mucosal goblet cell density and other histopathologic features reported in previous studies.