The microbiological spectrum and clinical course of adolescents and adults with peritonsillar abscesses.

A peritonsillar abscess (PTA) displays a purulent infection arising from acute tonsillitis, involving a variety of aerobic and anaerobic bacteria. Fusobacterium necrophorum, a gram-negative anaerobe, is considered a significant risk factor for complications like Lemierre's syndrome. This study aimed to analyze the microbiological spectrum of PTA and its impact on the clinical course and outcomes. This retrospective study included all patients diagnosed with PTA at a tertiary care center between January 2018 and June 2023. Data on patient demographics, inflammatory markers, microbiological aspects (including species identification and antibiotic therapy), and clinical management were collected. Overall, 321 patients with a mean age of 34.1 years were included. Most patients (80.1%) underwent tonsillectomy, while others received surgical incision and drainage (18.1%) or no surgical treatment (1.9%). Patients with tonsillectomy had a significantly longer hospital stay compared to those with incision and drainage (5.4 ± 2.5 days vs. 4.4 ± 1.3 days; adjusted p = 0.004). Surgical complications were more frequent in patients with tonsillectomy (13.6% vs. 1.7%; adjusted p = 0.048), whereas ipsilateral recurrence was more common in patients with incision and drainage (8.6% vs. 0.0%; adjusted p = 0.004). Higher CRP levels at admission (p = 0.002) were predictive for a higher risk of infection-related complications. Streptococcus pyogenes was the most frequently identified pathogen (25.9%), followed by Streptococci of the anginosus group (15.3%), and Fusobacterium necrophorum (FN; 11.5%), which was significantly more common in adolescents (age < 18 years; 25.3%) than in adult patients (9.5%; adjusted p = 0.020) and had high antibiotic susceptibility rates with 100% to clindamycin and 96.6% to penicillin or aminopenicillin with beta-lactamase inhibitor, the latter being administered to the majority (87.2%) of patients as empiric antibiotic treatment. This study provides insights into the demographic, clinical, and microbiological characteristics of PTAs. Consistent with previous literature, this study shows a higher frequency of FN in PTAs in adolescents and young adults. However, unlike previous reports, this was not associated with increased complication rates.