Streptokoktest

Streptokoktest is a diagnostic test used to detect Streptococcus bacteria, most often in the context of throat infections. It is commonly employed to diagnose streptococcal pharyngitis caused by Streptococcus pyogenes, also known as group A Streptococcus, but can be used for other suspected streptococcal infections or carriers as indicated by the clinical setting.

Common methods include rapid antigen detection tests (RADTs) for group A Streptococcus, throat culture, and nucleic acid amplification tests (NAATs) such as PCR. Serological tests, including assays for anti-streptolysin O (ASO) or other antibodies, are typically used to assess past infection or post-infectious sequelae rather than acute diagnosis.

The most frequent specimen for a streptokoktest is a throat swab, taken from the tonsillar area and posterior pharynx. Depending on the clinical scenario, samples from other sites (nasal, vaginal, or urethral) may be collected. RADTs provide rapid results within minutes, while throat cultures require longer processing time (often 24–48 hours). NAATs offer high sensitivity and are increasingly used in various settings. Serology is not useful for acute diagnosis but may support evaluation of prior exposure or rheumatic fever risk.

Interpretation and use vary by test type. A positive RADT typically confirms a group A Streptococcus infection and supports antibiotic treatment, whereas a negative RADT may be followed by a throat culture in children and adolescents or in patients with high clinical suspicion. Culture is considered the gold standard in many guidelines, and NAATs are valued for their accuracy. Limitations include possible false negatives with RADTs, false positives with some assays, and the impact of prior antibiotic use on test yield.

See also: Streptococcus pyogenes, strep throat, throat culture, rapid antigen test, PCR.