From the Guidelines
A throat swab is crucial in adults with suspected bacterial pharyngitis to confirm the diagnosis before initiating antibiotic therapy. When bacterial pharyngitis is suspected, particularly Group A Streptococcus (GAS), a rapid antigen detection test (RADT) or throat culture should be performed to avoid unnecessary antibiotic use 1. Only about 5-15% of adult sore throats are caused by GAS, making empiric treatment without testing problematic. If testing confirms GAS pharyngitis, penicillin V (250-500 mg orally twice daily for 10 days) remains the first-line treatment due to its narrow spectrum and lack of resistance. Alternatives for penicillin-allergic patients include cephalexin (if no anaphylactic reaction history) or macrolides like azithromycin (500 mg on day 1, then 250 mg daily for 4 more days) 1.
Some key points to consider:
- Clinical scoring systems like the Centor criteria (fever, tonsillar exudates, tender anterior cervical lymphadenopathy, absence of cough) can help determine which patients should undergo testing, but they are not reliable enough to diagnose bacterial pharyngitis without confirmatory testing 1.
- Testing helps reduce antibiotic overuse, which contributes to antimicrobial resistance and exposes patients to unnecessary medication side effects.
- Routine use of back-up throat cultures for those with a negative RADT is not necessary for adults in usual circumstances, because of the low incidence of GAS pharyngitis in adults and the risk of subsequent acute rheumatic fever is generally exceptionally low in adults with acute pharyngitis 1.
Overall, performing a throat swab in adults with suspected bacterial pharyngitis is essential to guide appropriate antibiotic use and prevent unnecessary treatment.
From the Research
Importance of Throat Swab in Adults
- A throat swab is important in adults with suspected bacterial pharyngitis, particularly for diagnosing group A streptococcal pharyngitis 2, 3, 4, 5, 6
- The diagnosis of group A streptococcal pharyngitis is crucial because it can trigger post-infection systemic complications, such as acute rheumatic fever and post-streptococcal glomerulonephritis 5
- Throat culture is considered the gold standard for diagnosing streptococcus pharyngitis, but rapid antigen detection tests can also be used to detect group A streptococcus directly from throat swabs within minutes 2, 5
Diagnostic Methods
- Clinical scoring systems, such as the modified Centor score, can be used to predict the risk of group A streptococcal infection 4, 5
- Rapid antigen detection tests and throat cultures are commonly used diagnostic methods for group A streptococcal pharyngitis 2, 4, 5, 6
- Nucleic acid amplification tests and machine learning and artificial intelligence are also being explored as diagnostic methods for group A streptococcal pharyngitis 6
Treatment and Management
- Antibiotic treatment is only beneficial for patients with group A streptococcal infection, and penicillins are the first-choice treatment 4, 5, 6
- Clinical guidelines developed by professional associations can help medical professionals choose among available techniques to diagnose and treat group A streptococcal pharyngitis, but there is substantial evidence that most physicians do not follow any published guidelines 6
- The use of antibiotics should be minimized to prevent unnecessary use and reduce the risk of antibiotic resistance 4, 6