Microbiology of peritonsillar abscess in the South Estonian population.

Objective: The first aim of this study was to compare the microbiota of different locations (pus, tonsillar fossa, blood) in peritonsillar abscess (PTA) patients in order to optimize the sampling scheme. The second aim was to estimate the occurrence of tonsillitis episodes and macroscopic oropharyngeal signs characteristic of recurrent tonsillitis in PTA patients.

Methods: The study group consisted of 22 consecutive patients with PTA undergoing bilateral tonsillectomy. The PTA was punctured; pus and tonsillar fossa biopsy samples and the peripheral blood cultures were collected. The index of tonsillitis was calculated by multiplying the number of tonsillitis episodes per year by the morbidity period in years. Macroscopic oropharyngeal signs were evaluated and they were as follows: tonsillar sclerosis, obstruction of the tonsillar crypts, scar tissue on tonsils, cryptic debris, and lymphatic tissue aggregates.

Results: The cultures of the pus were positive in 16 out of 22 patients and the cultures of the tonsillar fossa samples were positive in all cases. In total, 62 different organisms were found from tonsillar fossa, pus, and blood samples, which belonged to 5 different phyla and 18 different families.In the tonsillar fossa, the most frequent bacteria found were Streptococcus spp. In pus samples, the most frequently found bacteria were Streptococcus spp. and bacteria from the Streptococcus milleri group.

Conclusion: PTA patients had mixed anaerobic and aerobic microbiota both in the tissue of the tonsillar fossa and the pus of the peritonsillar space. We demonstrated that the tonsillar fossa specimen is a better material for microbiological analyses, because it reveals more bacteria per culture. PTA patients usually have a low number of tonsillitis episodes in their previous history, but a relatively high number of macroscopic oropharyngeal signs, indicating the sclerotic process in palatal tonsils.