Bacterial findings in patients referred to hospital for the treatment of acute tonsillitis with or without peritonsillar phlegmon

Abstract Background The vast majority of patients with acute tonsillitis (AT) are managed in general practice. However, occasionally patients are referred to hospital for specialized management because of aggravated symptoms and/or findings suggestive of peritonsillar involvement. No prospective studies have been conducted aiming to investigate the prevalent and significant microorganisms in this highly selected group of patients. We aimed to describe the microbiological findings of acute tonsillitis with or without peritonsillar phlegmon (PP) in patients referred for hospital treatment and to point out potential pathogens using the following principles to suggest pathogenic significance: (1) higher prevalence in patients compared to healthy controls, (2) higher abundance in patients compared to controls, and (3) higher prevalence at time of infection compared to time of follow up. Methods Meticulous and comprehensive cultures were performed on tonsillar swabs from 64 patients with AT with (n = 25) or without (n = 39) PP and 55 healthy controls, who were prospectively enrolled at two Danish Ear-Nose-Throat Departments between June 2016 and December 2019. Results Streptococcus pyogenes was significantly more prevalent in patients (27%) compared to controls (4%) (p