Certain populations require special consideration for antibiotic use. Any patient with a history of rheumatic fever or a family member with suspected or documented strep pharyngitis should receive prompt treatment with antibiotics.^9,15 A second category is the patient who has already started “leftover” antibiotics at home prior to diagnosis; as few as two doses of antibiotics may invalidate GABHS laboratory results.¹⁶ A third category is those with pharyngitis in the setting of a local outbreak of rheumatic fever. Finally, patients with strep pharyngitis that recurs at least 7 days but within 4 weeks of completing prior antibiotic therapy should be considered for an additional course of antibiotics. Patients may be a carrier of GABHS (10%-25% of the U.S. population).²

Alternatively, treatment failure may occur because of medication noncompliance, alternative pathogens, or rare cases with pharyngeal flora producing beta-lactamase. What are the options in these situations? Consider antibiotics if:

• Clinical or laboratory findings suggest GABHS.
• The patient is 5-15 years old and it is a higher-incidence season, such as winter or spring.
• The patient has had repeated, marked clinical response to antibiotic therapy.
• Throat cultures are negative between episodes of pharyngitis (less likely carrier state).¹

Appropriate Antibiotic Selection

Based on cost, narrow spectrum of activity, safety, and effectiveness, penicillin continues to be recommended as the first-line agent by the American Academy of Family Physicians (AAFP), AAP, AHA, IDSA, and the World Health Organization for the treatment of streptococcal pharyngitis.⁸ Oral therapy for 10 days is standard. Despite many years of use, penicillin resistance remains rare and allows for the option of a single-dose intramuscular injection of penicillin G benzathine (Bicillin L-A) or a premixed penicillin G benzathine/procaine injection (Bicillin C-R) to lessen injection-associated discomfort.

Why treat with an antibiotic other than penicillin? The main reason will be an allergy to penicillins. Erythromycin is a suitable alternative, and clindamycin is a recommended second-line agent in patients unable to tolerate erythromycin. In the pediatric population, support continues to grow for using amoxicillin, primarily because of its better taste and less-frequent dosing regimen. Amoxicillin once daily (750 mg for those weighing less than 30 kg, 1,000 mg for those weighing more) may be as effective as a regimen of two to three times per day. Small studies have demonstrated comparable symptom relief, including a recent study of children and adolescents 3-18 years old that showed once-daily dosing to be as effective as twice-daily dosing.^17,18 Although this regimen is being used by some practitioners, especially pediatricians, readers should be aware that once-daily therapy is not approved by the Food and Drug Administration.