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Clarithromycin and penicillin had a similar overall clinical success rate in group A β-hemolytic streptococcal pharyngitis

ACP J Club. 1993 May-June;118:82. doi:10.7326/ACPJC-1993-118-3-082

Source Citation

Schrock CG. Clarithromycin vs penicillin in the treatment of streptococcal pharyngitis. J Fam Pract. 1992 Dec;35:622-6.



To compare the efficacy and safety of clarithromycin and penicillin for pharyngitis caused by group A β-hemolytic streptococci.


Randomized, single-blind, multicenter, controlled trial.


30 family practice clinics.


453 patients (mean age 30 y, 60% men) with an initial episode of culture- or immunoassay-proven pharyngitis caused by group A β-hemolytic streptococci. Patients had at least 1 of pharyngeal erythema or exudate, tenderness of cervical lymph nodes, or fever. Exclusion criteria were hypersensitivity to the study drugs, rheumatic fever, cardiac valvular disease, allergies, asthma, risk for pregnancy, or administration of a systemic antibiotic within the previous 2 weeks, penicillin within 6 weeks, or other drugs within 4 weeks.


226 patients were randomized to receive clarithromycin, 250 mg every 12 hours, and 227 patients were randomized to receive penicillin VK, 250 mg every 8 hours. Recommended treatment duration was 10 days.

Main outcome measures

Patient examinations and throat cultures were done before randomization, 5 to 7 days later, and 4 to 6 days and 19 to 25 days after the conclusion of treatment. Major end points were sore throat, pharyngeal erythema or exudate, lymph node tenderness, fever, abdominal pain, headache, drug side effects, and bacteriologic cure.

Main results

179 patients who took clarithromycin and 177 patients who took penicillin had culture-confirmed pharyngitis, completed ≥ 7 days of treatment, and had complete follow-up data. Patients who took clarithromycin, compared with those who took penicillin, had the same clinical success rate (sign and symptoms of infection before treatment were resolved or were lessened, 97%), but a higher resolution of sore throat (94% vs 86%, {95% CI for difference 2% to 14%}*, P = 0.014), less pharyngeal erythema or exudate (89% vs 82%, {CI for difference 0% to 14%}*, P = 0.05), and a higher bacteriologic cure rate after treatment (95% vs 87%, {CI for difference 2% to 14%}*, P = 0.009). Using data from all 453 patients, the groups did not differ for adverse effects, lymph node tenderness, abdominal pain, or recurrence.


Patients with group A β-hemolytic streptococci pharyngitis who took clarithromycin twice daily compared with those who took penicillin 3 times daily had a comparable clinical success rate overall, although there was a slight improvement in terms of resolution of sore throat, presence of erythema or exudate, and bacteriologic cure rate after treatment. The groups did not differ for side effects or resolution of other symptoms.

Source of funding: In part, Abbott Laboratories.

For article reprint: Dr. C.G. Schrock, Oakdale Medical Building, 3366 Oakdale Avenue North, Suite 520, Minneapolis, MN 55422, USA. FAX 612-520-7035.

*Numbers calculated from data in article.


Pharyngitis caused by group A β-hemolytic streptococci is treated to prevent rheumatic fever and suppurative complications such as sinusitis and otitis media. Current therapy involves a 10-day course of penicillin or, in patients allergic to penicillin, erythromycin. The cost of treating streptococcal pharyngitis with the new macrolide, clarithromycin, is about 10 times that of penicillin and 5 times that of erythromycin. Does clarithromycin have an advantage over traditional therapy that justifies this cost difference?

In comparing clarithromycin with penicillin, the study suggests that patients treated with clarithromycin resolved their throat discomfort more quickly and were less likely to have streptococcus on throat culture done shortly after treatment. The differences were small and their meaning was obscured by the fact that treatment varied from 7 to 10 days and patients who received less than optimal therapy with each drug were not identified. Thus, it is not clear whether the slightly better outcome of patients treated with clarithromycin was caused by greater drug effectiveness or by longer treatment.

The significance of streptococcus on throat culture after a full course of penicillin is controversial. It is generally believed that, except in certain high-risk circumstances, re-treatment is required only when a positive throat culture is associated with persistent or new symptoms (1). Unfortunately, the study fails to make clear which patients, if any, with positive throat cultures after treatment were symptomatic. For this reason, the clinical importance of the difference in the bacteriologic "cure" rate favoring clarithromycin remains uncertain.

In any case, patients requiring a second course of therapy may be treated with erythromycin, which is just as effective as clarithromycin and is much cheaper (2).

Jaime B. Friedman, MD
Sand Point InternistsSeattle, Washington, USA


1. McCracken GH Jr. Diagnosis and management of children with streptococcal pharyngitis. Pediatr Infect Dis. 1986;5:754-9.

2. Scaglione F. Comparison of the clinical and bacteriological efficacy of clarithromycin and erythromycin in the treatment of streptococcal pharyngitis. Curr Med Res Opin. 1990;12:25-32.