Associations Between Findings of Fusobacterium necrophorum or β-Hemolytic Streptococci and Complications in Pharyngotonsillitis-A Registry-Based Study in Southern Sweden

In patients with pharyngotonsillitis evaluated for Fusobacterium necrophorum and beta-hemolytic streptococci, a finding of F. necrophorum or group A streptococci was associated with increased complication rates. Inversely, a finding of group C/G streptococci was associated with fewer complications than in patients with negative results. Background Most pharyngotonsillitis guidelines focus on the identification of group A streptococci (GAS), guided by clinical scores determining whom to test with a rapid antigen detection test. Nevertheless, many patients testing negative with this test are evaluated for group C/G streptococci (GCS/GGS) and Fusobacterium necrophorum, yet their importance remains debated. Our primary aim was to evaluate associations between complications and findings of F. necrophorum, GAS, or GCS/GGS in pharyngotonsillitis. Methods This was a retrospective, registry-based study of pharyngotonsillitis cases tested for F. necrophorum (polymerase chain reaction) and beta-hemolytic streptococci (culture) in the Skane Region, Sweden, in 2013-2020. Patients with prior complications or antibiotics (within 30 days) were excluded. Data were retrieved from registries and electronic charts. Logistic regression analyses were performed with a dichotomous composite outcome of complications as primary outcome, based on International Classification of Diseases, Tenth Revision, codes. Cases with negative results (polymerase chain reaction and culture) were set as reference category. Complications within 30 days were defined as peritonsillar or pharyngeal abscess, otitis, sinusitis, sepsis or septic complications, recurrence of pharyngotonsillitis (after 15-30 days) or hospitalization. Results Of 3700 registered cases, 28% had F. necrophorum, 13% had GCS/GGS, 10% had GAS, and 54% had negative results. The 30-day complication rates were high (20%). F. necrophorum (odds ratio, 1.8; 95% confidence interval, 1.5-2.1) and GAS (1.9; 1.5-2.5) were positively associated with complications, whereas GCS/GGS were negatively associated (0.7; 0.4-0.98). Conclusions Our results indicate that F. necrophorum is a relevant pathogen in pharyngotonsillitis, whereas the relevance of testing for GCS/GGS is questioned. However, which patient to test and treat for F. necrophorum remains to be defined.

Automated summary

In patients with pharyngotonsillitis, the presence of F. necrophorum or group A streptococci is associated with higher complication rates, while the presence of group C/G streptococci is associated with fewer complications.