Precipitating factors in the pathogenesis of peritonsillar abscess and bacteriological significance of the Streptococcus milleri group.

Peritonsillar abscess (PTA) is conventionally considered to be a complication of acute tonsillitis, but no pathogenical association has been demonstrated. To investigate the precipitating factors in the pathogenesis of PTA, the clinical status of 117 patients with PTA and 78 patients with peritonsillar cellulitis (PC) were reviewed, comparing them with 188 cases of acute tonsillitis as a control group. The period between the onset of symptoms and the date of starting hospitalized medication was 4 to 5 days in all the three groups, with no significant differences. Higher prevalence of smoking habit was noted in the PTA group (odds ratio, 1.92; 95% confidence interval, 1.17-3.16). Bacteriological culture revealed that 55 of 67 aerobic isolates were Streptococcus subspecies, with the Streptococcus milleri group (SMG) as the most common (20 isolates). Twenty-three anaerobic species were isolated. Only 51% of the patients with neither the SMG nor anaerobic bacteria were smokers, whereas 90% of the patients with both the SMG and anaerobic bacteria were smokers. We hypothesize that delay or failure to receive medical care do not contribute to the pathogenesis of PTA or PC, and that smoking is positively correlated with the occurrence of PTA, as well as the bacteriological character.