What test is primarily used to diagnose streptococcal pharyngitis?

The rapid strep test is primarily used to diagnose streptococcal pharyngitis due to its efficiency and speed in detecting Group A Streptococcus in throat swab samples. This test utilizes antibodies to specifically identify the presence of streptococcal antigens, providing results within a short timeframe, often in less than 15 minutes. This rapid diagnosis enables prompt treatment, which can help alleviate symptoms and prevent complications such as rheumatic fever.

While throat cultures are a standard method for confirming the diagnosis, they take longer to process and are typically used if the rapid test is negative but clinical suspicion remains high. In contrast, imaging studies like a chest X-ray are not relevant for diagnosing throat infections, and a complete blood count may provide supportive information regarding the presence of infection but does not specifically diagnose streptococcal pharyngitis. The rapid strep test is thus favored in clinical practice for its ability to quickly identify the pathogen responsible for the condition.