Background: The study investigates whether relapses of chronicpharyngotonsillitis result from new infections caused by theoro-pharyngeal microbial flora or are reactivations of persistent bacterial infections of the tonsils.
Methods: 90 patients, who were surgically treated for chronicpharyngotonsillitis (age 13 months to 38 years, at least 5 episodes of disease and antibiotic treatment in the past) were included. The surgery was performed in the antibiotic- and symptom-free period (at least 6 weeks after the last exacerbation). Sections of tonsillar tissue were investigated for invasive bacteria using fluorescence in situ hybridization (FISH) with group and species-specific 15/23S RNA based probes.
Results: Abundant foci of invasive bacteria were found in 86% of the resected tonsils, despite previous treatment with antibiotica and absent symptoms of ongoing infection. The diffuse infiltration of the tonsils was most predominant in the youger children. Local invasive processes such as abscesses, fissures filled with pus and superficial infiltration of the tonsillar epithelium were more typical for adults. All of the foci were polymicrobial and contained up to 10 different species or groups of bacteria. The local concentrations of invasive bacteria were up to 1012 bacteria/ml.
Conclusions: The chronic pharyngotonsillitis is the result of persistent invasive bacterial infections. The polymicrobial nature of the infectious foci enables them to resist the antibiotic treatment and to exacerbate afterwards. The surgical treatment is unavoidable as long as antibiotic treatment fails to clear the infection.