Based on the presence of fever, tender lymphadenopathy, and tonsillar exudate—and the absence of cough—the physician strongly suspected group A β-hemolytic Streptococcus (GABHS) pharyngitis and prescribed oral penicillin VK. GABHS accounts for 5% to 10% of pharyngitis in adults and 15% to 30% in children. Up to 38% of cases of tonsillitis are because of GABHS.
The following criteria are helpful in the diagnosis of GABHS pharyngitis:
○ history of fever or temperature of 38°C (100.4°F) (1 point)
○ absence of cough (1 point)
○ tender anterior cervical lymph nodes (1 point)
○ tonsillar swelling or exudates (1 point)
○ age: <15 years (1 point); 15 to 45 years (0 points); >45 years (–1 point).
The probability of GABHS is approximately 1% with –1 to 0 points and approximately 51% with 4 to 5 points.
Rapid antigen detection is often used to diagnose GABHS. Test options include enzyme immunoassays, latex agglutination, liposomal method, and immunochromatographic assays. The immunochromatographic assay has the highest reported sensitivity (97%), specificity (97%), and positive (32.3) and negative (0.03) likelihood ratios.
In this patient’s case, the likelihood of strep pharyngitis was high enough that a rapid strep test was not performed. For suspected or proven GABHS, penicillin VK 500 mg orally 2 to 3 times daily for 10 days continues to be the treatment of choice for adults. Erythromycin 500 mg orally 4 times daily may be used in penicillin allergic patients. Treatment should also include analgesics/antipyretics, as needed, plenty of fluids, and rest.
Photo courtesy of Michael Nguyen, MD. Text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Williams, B, Usatine R, Smith M. Pharyngitis. In: Usatine R, Smith M, Mayeaux EJ, et al. Color Atlas of Family Medicine. 2nd ed. New York, NY: McGraw-Hill; 2013:213-219.
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