Prevalence of group C streptococcus and Fusobacterium necrophorum in patients with sore throat: A meta-analysis

PURPOSE The prevalence of Group C beta-hemolytic streptococcus and Fusobacterium necrophorum among patients with sore throat in the outpatient setting has not been previously summarized. We set out to derive prevalence information from the existing literature. METHODS We performed a systematic review of MEDLINE for studies reporting the prevalence of F necrophorum or Group C streptococcus or both in prospective, consecutive series of outpatients with sore throat, as well as laboratory-based studies of throat cultures submitted from primary care. We limited searches to studies where the majority of data was collected after January 1, 2000, to reflect contemporary microbiological methods and prevalences. Each author independently reviewed the articles for inclusion and abstraction of data; we resolved discrepancies by consensus discussion. We then performed a meta-analysis to calculate the pooled prevalence estimates using a random effects model of raw proportions. RESULTS A total of 16 studies met our inclusion criteria. The overall prevalences of Group C streptococcus and F necrophorum were 6.1% (95% CI, 3.2%-9.0%) and 18.9% (95% CI, 10.5%-27.2%), respectively. When stratified by study type, the prevalences of Group C streptococcus and F necrophorum in laboratory-based studies were 6.6% (95% CI, -1.0% to 14.2%) and 18.8% (95% CI, 6.5%-31.1%), respectively. In primary care patients with sore throat, Group C streptococcus had a prevalence of 6.1% (95% CI, 3.1%-9.2%), while F necrophorum had a prevalence of 19.4% (95% CI, 14.7%-24.1%). CONCLUSIONS Group C streptococcus and Fusobacterium necrophorum are commonly detected in patients with acute pharyngitis. Research is needed, however, to determine whether these bacteria are truly pathogenic in patients with pharyngitis and whether antibiotics reduce the duration of symptoms or the likelihood of complications.