Rapid antigen detection testing in diagnosing group A β-hemolytic streptococcal pharyngitis

Abstract

Group A beta-hemolytic streptococcus (GABHS) is the most common bacterial cause of acute pharyngitis. Clinical criteria alone are not reliable enough to diagnose GABHS pharyngitis. Microbiological-testing is required for correct diagnosis. Although a throat swab culture remains the gold standard for documenting the presence of GABHS, a significant disadvantage of the culture is the delayed time of 1-2 days to obtain results. Most rapid antigen detection tests can provide results in less than 15 min. Rapid identification and treatment of patients with GABHS pharyngitis can reduce the risk of the spread of disease, may shorten the duration of symptoms, decrease the incidence of suppurative complications, decrease the amount of time lost from school/work, decrease the inappropriate use of antibiotics, reduce patient/parent dissatisfaction and alleviate the need for costly follow-up visits. All rapid antigen detection tests involve extraction of the group-specific carbohydrate antigen from the GABHS cell wall and identification of the antigen by an immunological reaction. There are numerous rapid antigen detection testing methods, namely latex agglutination, enzyme immunoassay, optical immunoassay, chemiluminescent DNA probes and PCR methods. Most of the rapid antigen detection tests that are currently in use have an excellent specificity of greater than 95% and a sensitivity of greater than or equal to 90%. Owing to the high specificity of the rapid antigen detection tests, a positive rapid antigen detection test is accepted as adequate for the diagnosis of GABHS pharyngitis. Conversely, confirmation of a negative antigen detection test with a throat culture result is necessary, unless the physician has ascertained in his/her practice that the sensitivity of the rapid antigen test used is comparable with that of a throat culture.

Molecular and Clinical Diagnosis of Group A Streptococcal Pharyngitis in Children

“…In 2 cases, there was documentation of prior exposure to amoxicillin; in the third case, no information on antibiotic exposure prior to testing could be retrieved. These 3 cases were considered true-positive cases, as RADT has been reported to be highly specific and, according to current guidelines, confirmation is not required (3,30). However, the fact that the results for these samples were not confirmed with the alternate PCR assay can be considered a limitation.…”

Rapid Diagnostic Tests for Group A Streptococcal Pharyngitis: A Meta-analysis

“…46 These 2 more recently developed RADTs have a turnaround time of 1 to 2 hours and require special laboratory setups, which may necessitate follow-up with patients for relaying results, as compared with other techniques that are true point-of-care tests. 8 …”

“…7 Since their inception in the early 1980s, there have been several generations of RADTs that have used different methodologies. 8 The firstgeneration tests used latex agglutination, followed by enzyme-linked immunosorbent assays (ELISAs), lateral flow and immunochromatographic assays, and optical immunoassays (OIAs). More recently, molecular-based techniques, such as DNA probes, polymerase chain reaction (PCR), and fluorescence in situ hybridization (FISH) methods, have been developed.…”

“…More recently, molecular-based techniques, such as DNA probes, polymerase chain reaction (PCR), and fluorescence in situ hybridization (FISH) methods, have been developed. 8 RADTs have been incorporated into both the Infectious Diseases Society of America and the European Society for Clinical Microbiology and Infectious Diseases clinical practice guidelines, 4,9 but are not used routinely in all countries, including Australia. 10 Widespread use of RADTs has been hindered by low sensitivity for most commonly used RADTs (immunoassays).…”

Acute tonsillitis on the pediatric district: etiologic diagnosis and treatment

“…Этот метод основан на иммунохроматографическом иссле-довании специфического антигена стрептококка груп-пы А в материале, полученном из мазка со слизистой оболочки задней глотки или небных миндалин [12,13]. Оценить результат у постели больного можно уже через 5-10 мин.…”