Association between C-Reactive Protein Rapid Test and Group A Streptococcus Infection in Acute Pharyngitis

Introduction: The diagnosis of streptococcal infection is usually made with the use of Centor criteria, but some family doctors also rely on the determination of C-reactive protein (CRP) to guide antibiotic therapy.

Methods: This was an observational study conducted in a health center. Adults with acute pharyngitis and the presence of the 4 Centor criteria (tonsillar exudates, tender cervical glands, history of fever, and absence of cough) were recruited. The patients underwent a pharyngotonsillar swab for microbiologic study and a CRP rapid test during the consultation.

Results: A total of 149 patients were enrolled. The most frequent etiology was group A streptococcus, present in 83 cases (55.7%). The highest CRP concentration was observed among patients with group C streptococcus infection, with a mean of 56.3 mg/L (95% confidence interval, 25.7–86.5 mg/L). For patients with group A streptococcus infection, the mean CRP value was 34.4 (95% confidence interval, 25.6–43.3 mg/L).

Conclusion: CRP concentrations are not associated with group A streptococcus infection in patients with acute pharyngitis. The use of this point of care test is therefore not useful for distinguishing patients who require antibiotic therapy.