What are the guidelines for evaluating acute pharyngitis (inflammation of the pharynx)?

From the Guidelines

The primary guideline for evaluating acute pharyngitis is to perform throat swabbing and testing for Group A Streptococcal (GAS) pharyngitis by rapid antigen detection test (RADT) and/or culture, as clinical features alone do not reliably discriminate between GAS and viral pharyngitis 1. When evaluating acute pharyngitis, it is essential to consider the clinical features and use them to guide testing decisions.

• The presence of overt viral features like rhinorrhea, cough, oral ulcers, and/or hoarseness can help discriminate between GAS and viral pharyngitis.
• In children and adolescents, negative RADT tests should be backed up by a throat culture, as the risk of GAS pharyngitis is higher in this population 1.
• In adults, routine use of back-up throat cultures for those with a negative RADT is not necessary, due to the low incidence of GAS pharyngitis and the low risk of subsequent acute rheumatic fever 1. Key considerations in evaluating acute pharyngitis include:
• The use of anti-streptococcal antibody titers is not recommended in the routine diagnosis of acute pharyngitis, as they reflect past but not current events 1.
• The importance of using RADT and/or culture to confirm the diagnosis of GAS pharyngitis, rather than relying solely on clinical features. By following these guidelines, clinicians can ensure appropriate testing and treatment for patients with acute pharyngitis, while reducing unnecessary antibiotic use and minimizing the risk of complications such as acute rheumatic fever.

From the FDA Drug Label

Pharyngitis/Tonsillitis In three double-blind controlled studies, conducted in the United States, azithromycin (12 mg/kg once a day for 5 days) was compared to penicillin V (250 mg three times a day for 10 days) in the treatment of pharyngitis due to documented Group A β-hemolytic streptococci (GABHS or S. pyogenes) Azithromycin was clinically and microbiologically statistically superior to penicillin at Day 14 and Day 30 with the following clinical success (i.e., cure and improvement) and bacteriologic efficacy rates (for the combined evaluable patient with documented GABHS): Three U. S. Streptococcal Pharyngitis Studies Azithromycin vs. Penicillin V EFFICACY RESULTS Day 14 Day 30 Bacteriologic Eradication: Azithromycin 323/340 (95%) 255/330 (77%) Penicillin V 242/332 (73%) 206/325 (63%) Clinical Success (Cure plus improvement): Azithromycin 336/343 (98%) 310/330 (94%) Penicillin V 284/338 (84%) 241/325 (74%)

The guidelines for evaluating acute pharyngitis are to assess clinical success (i.e., cure and improvement) and bacteriologic efficacy rates at Day 14 and Day 30.

• Bacteriologic eradication rates should be evaluated, with azithromycin showing 95% eradication at Day 14 and 77% at Day 30.
• Clinical success rates should be evaluated, with azithromycin showing 98% success at Day 14 and 94% at Day 30. The recommended dose of azithromycin for children with pharyngitis/tonsillitis is 12 mg/kg once daily for 5 days 2. Key points to consider when evaluating acute pharyngitis include:
• Clinical success rates
• Bacteriologic efficacy rates
• Bacteriologic eradication rates
• Dosing regimen: 12 mg/kg once daily for 5 days for children with pharyngitis/tonsillitis 2.

From the Research

Guidelines for Evaluating Acute Pharyngitis

The guidelines for evaluating acute pharyngitis are based on the principles of appropriate antibiotic use, which apply to immunocompetent adults without complicated comorbid conditions, such as chronic lung or heart disease, and history of rheumatic fever 3, 4. The key points are:

• Group A beta-hemolytic streptococcus (GABHS) is the causal agent in approximately 10% of adult cases of pharyngitis.
• Antibiotic treatment of adult pharyngitis benefits only those patients with GABHS infection.
• All patients with pharyngitis should be offered appropriate doses of analgesics and antipyretics, as well as other supportive care.

Clinical Screening

Clinically screen all adult patients with pharyngitis for the presence of the four Centor criteria:

• History of fever
• Tonsillar exudates
• No cough
• Tender anterior cervical lymphadenopathy (lymphadenitis) Do not test or treat patients with none or only one of these criteria, since these patients are unlikely to have GABHS infection 3, 4.

Diagnostic Testing

For patients with two or more criteria, the following strategies are appropriate:

• Test patients with two, three, or four criteria by using a rapid antigen test, and limit antibiotic therapy to patients with positive test results.
• Test patients with two or three criteria by using a rapid antigen test, and limit antibiotic therapy to patients with positive test results or patients with four criteria.
• Do not use any diagnostic tests, and limit antibiotic therapy to patients with three or four criteria 3, 4. Throat cultures are not recommended for the routine primary evaluation of adults with pharyngitis or for confirmation of negative results on rapid antigen tests when the test sensitivity exceeds 80% 3, 4.

Rapid Antigen Detection Tests

The diagnostic value of a rapid antigen test for the diagnosis of streptococcal pharyngitis in pediatric patients is high, but the percentage of false positives and negatives is too high, and the sensitivity is too low in patients with fewer symptoms to support the use of rapid antigenic test without culture confirmation and bacterial sensitivity test 5. In contrast, a study found that an extremely low percentage (< 1 percent) of subjects with GABHS escaped detection with rapid screening test methods, and results supported treatment protocols based on a rapid screening test as a single diagnostic test 6.

Adherence to Guidelines

Clinicians were adherent to the American College of Physicians' empirical strategy in 12% of visits, the American College of Physicians' test strategy in 30% of visits, the Infectious Diseases Society of America's strategy in 30% of visits, and adherent to none of these strategies in 66% of visits 7. The most common reason for nonadherence to any strategy was testing or antibiotic prescribing to patients at low risk of streptococcal pharyngitis, patients for whom the guidelines agree.