Background
Acute pharyngitis is one of the most common paediatric clinical presentations. Low- and middle-income countries suffer a large burden of disease from immunological sequelae of StrepA pharyngitis such as Rheumatic Heart Disease (RHD), responsible for over 300,000 deaths per year. Accurate diagnosis and treatment of StrepA pharyngitis in low-resource settings is imperative to prevent RHD whilst limiting unnecessary antibiotic use.
Methods
Children under 16 years presenting with acute pharyngitis were recruited at an urban health centre in The Gambia. We collected clinical information and performed a rapid antigen detection test (SD Bioline StrepA Strip), a rapid molecular test (ID NOW™ STREP A2) and microbiological culture for StrepA. Using latent class analysis (LCA), we assessed the performance of the tests and 5 clinical scoring systems at diagnosing StrepA pharyngitis.
Results
From 232 participants, 13.5% of pharyngeal swabs were culture-positive for StrepA, 29.7% were rapid antigen test-positive and 38.1% had a positive molecular test. LCA predicted 22.8% true StrepA positivity. Culture was highly specific (98.3%) but poorly sensitive (52.8%), while the molecular test was highly sensitive (100%) but less specific (80.5%). The rapid antigen test showed high sensitivity (94.3%) and specificity (89.4%). All the clinical scoring systems performed less well than both rapid tests and culture.
Conclusions
Culture for StrepA was poorly sensitive in this setting, but rapid antigen testing would improve diagnosis and management. Whilst the clinical scoring systems were less accurate, a structured management system including a score alongside rapid antigen testing, could be effective in The Gambia.