Rapid Diagnosis of Pharyngitis Caused by Group A Streptococci

Abstract

Although commercial rapid antigen detection tests (RADTs) are more expensive than blood agar plate (BAP) cultures, the advantage they offer is the speed with which they provide results. Rapid identification and consequent prompt treatment of patients with pharyngitis due to group A beta-hemolytic streptococci (GABHS) can reduce the risk of spread of GABHS, can allow patients to return to school or work sooner, and may reduce the acute morbidity of this illness. In most studies, RADTs have been compared with BAP cultures as the criterion standard. However, these comparisons are complicated by the fact that there is no universally accepted procedure for performing a BAP culture. The great majority of the RADTs that are currently available have a high specificity (i.e., 95% or greater) and a sensitivity of between 70 and 90% compared with BAP cultures. Few published studies have compared the performance of various RADTs to each other or examined the performance of various RADTs in the office setting. There is also relatively little published information about how physicians in practice actually use RADTs, but the available information suggests that many physicians do not follow recommended guidelines. While the development of easy-to-perform RADTs for the diagnosis of GABHS pharyngitis has altered clinical practice substantially, only limited data about cost-effectiveness are currently available

Management of patients with acute pharyngitis

“…4 A abrangência da investigação etiológica depende de objetivos a serem alcançados frente aos recursos técni-cos e financeiros disponíveis. Deve ser observado que 20% das crianças com faringite estreptocócica (5% do total de casos de faringite aguda) têm clínica pouco exuberante e potencial de complicações tardias [1][2][3][4] . De fato, uma parcela dos casos de doença reumática não registra antecedente de faringite importante 5 .…”

“…Os autores avaliaram a acurácia de um teste rápido e de parâmetros clínicos no diagnóstico da faringite por Streptococcus pyogenes frente à cultura de faringe o padrão ouro. As conclusões referendam as de outros estudos que mostram a maior acurácia do teste rápido [2][3][4] . A implicação na conduta pediátrica é direta, uma vez que o diagnóstico de faringite estreptocócica determina o tratamento com antibiótico para a prevenção das complicações tardias doença reumática e glomerulonefrite aguda 4 .…”

Management of acute streptococcal pharyngitis: still the subject of controversy

“…Thus, in children and adults in whom the clinical scoring systems indicate the risk of streptococcal pharyngitis, a definitive diagnosis of GAS pharyngitis requires identification of the bacterium in throat swab culture or rapid antigen detection test (RADT) [16,37]. RADT is based on acid extraction of cell-wall carbohydrate antigen and its detection with the use of specific antibody [38]. The success in isolating GAS in culture or obtaining a positive RADT result lies in a proper collection of throat swab.…”

Primary prevention of rheumatic fever in children: Key factors to consider

“…While the sensitivity of a few of these tests is low, the majority of modern tests have sensitivity >85% and nearly all have high specificity (>95%). [11] A number of immunoassay rapid tests and the majority of the newer molecular rapid tests have sensitivity >90%. These figures compare very favourably with the clinical decision rule outlined in the study, particularly because the higher specificity of rapid tests would substantially reduce overdiagnosis.…”