 A throat culture is the gold standard for the diagnosis of streptococcal pharyngitis , with a sensitivity of 90 – 95 % . A rapid strep test ( also called rapid antigen detection testing or RADT ) may also be used . While the rapid strep test is quicker , it has a lower sensitivity ( 70 % ) and statistically equal specificity ( 98 % ) as a throat culture . In areas of the world where rheumatic fever is uncommon , a negative rapid strep test is sufficient to rule out the disease . 
