A teen presents with sore throat and fever. Which diagnostic test should be ordered?

The rapid streptococcal antigen test is the most suitable diagnostic tool for a teen presenting with symptoms of sore throat and fever, particularly because these symptoms often suggest a bacterial infection caused by Streptococcus pyogenes, commonly known as strep throat.

This test provides quick results and is specifically designed to detect the presence of Group A Streptococcus in throat swabs, making it a first-line diagnostic approach in cases of suspected streptococcal pharyngitis. Quick identification of this bacterial infection is crucial as it can lead to both prompt treatment and prevention of complications that can arise from untreated strep throat, such as rheumatic fever.

In contrast, other tests like the ASO titer, which evaluates antibodies to streptolysin O produced by Streptococcus, are not as immediate or useful for diagnosing acute pharyngitis. A Monospot test is primarily used to detect infectious mononucleosis caused by Epstein-Barr virus, which, while it can present similarly, has a different treatment regimen. A CBC with differential can provide useful information about the white blood cell count and help differentiate between viral and bacterial infections, but it is not specific enough to confirm strep throat directly and does not guide immediate management like