Peritonsillar abscess: bacteriological evaluation.

The pus from a series of 41 peritonsillar abscesses was examined bacteriologically. In the majority of the abscesses a mixed bacterial flora was found. The specimens yielded 0-7 different bacterial species per abscess (mean 3.0). One species alone was isolated only in five cases (12.5%). Both anaerobic and aerobic bacteria were isolated from the specimens of 25 patients (61%), only anaerobes from two specimens (4.9%), and only facultative bacteria from 12 specimens (29%). Beta haemolytic streptococci were cultured in 43.9% of the cases, but Streptococcus pyogenes group A in only 10 cases (24.4%). Thus, the pus of the peritonsillar abscess seems to be caused by a mixed bacterial infection, where anaerobic bacteria play a significant role. Indications of tonsillectomy in cases with peritonsillar abscess are discussed.