Group A Streptococcus pharyngitis and pharyngeal carriage: A meta-analysis

Objective Antibiotic treatment of Group A Streptococcus (GAS) pharyngitis is important in acute rheumatic fever (ARF) prevention, however clinical guidelines for prescription vary. GAS carriers with acute viral infections may receive antibiotics unnecessarily. This review assessed the prevalence of GAS pharyngitis and carriage in different settings. Methods A random-effects meta-analysis was performed. Prevalence estimates for GAS+ve pharyngitis, serologically-confirmed GAS pharyngitis and asymptomatic pharyngeal carriage were generated. Findings were stratified by age group, recruitment method and country income level. Medline and EMBASE databases were searched for relevant literature published between 1 January 1946 and 7 April 2017. Studies reporting prevalence data on GAS+ve or serologically-confirmed GAS pharyngitis that stated participants exhibited symptoms of pharyngitis or upper respiratory tract infection (URTI) were included. Included studies reporting the prevalence of asymptomatic GAS carriage needed to state participants were asymptomatic. Results 285 eligible studies were identified. The prevalence of GAS+ve pharyngitis was 24.1% (95% CI: 22.6-25.6%) in clinical settings (which used 'passive recruitment' methods), but less in sore throat management programmes (which used 'active recruitment', 10.0%, 8.1-12.4%). GAS+ve pharyngitis was more prevalent in high-income countries (24.3%, 22.6-26.1%) compared with low/middle-income countries (17.6%, 14.9-20.7%). In clinical settings, approximately 10% of children swabbed with a sore throat have serologically-confirmed GAS pharyngitis, but this increases to around 50-60% when the child is GAS culture-positive. The prevalence of serologically-confirmed GAS pharyngitis was 10.3% (6.6-15.7%) in children from high-income countries and their asymptomatic GAS carriage prevalence was 10.5% (8.4-12.9%). A lower carriage prevalence was detected in children from low/middle income countries (5.9%, 4.3-8.1%). Conclusions In active sore throat management programmes, if the prevalence of GAS detection approaches the asymptomatic carriage rate (around 6-11%), there may be little benefit from antibiotic treatment as the majority of culture-positive patients are likely carriers.