Macrolide therapy of group A streptococcal pharyngitis: 10 days of macrolide therapy (clarithromycin) is more effective in streptococcal eradication than 5 days (azithromycin)

We compared recommended doses of 2 oral macrolide antibiotics (10 days of c larithromycin, 5 days of azithromycin) for eradicating group A streptococci from the throats of individuals aged greater than or equal to 12 years wit h symptomatic pharyngitis and a positive throat culture. Patients received either clarithromycin (250 mg b.i.d. for 10 days [n = 260]) or azythromycin (500 mg on day 1, followed by 250 mg q.d. for 4 days [n = 265]). Follow-up throat cultures were obtained both at 13-19 days and at 28-38 days. We eva luated 392 patients (median age, 26 years; clarithromycin, 194 patients; az yithromycin, 198 patients). Ten days of clarithromycin therapy was more eff ective than 5 days of azithromycin therapy in eradicating the organism (91% [176/194] vs. 82% [162/198]; P = .012). More than 97% of all streptococcal isolates were macrolide-sensitive. Whether these bacteriologic eradication rates were the result of the 2 macrolides compared or were due to differen ces in duration of therapy could not be determined, but the statistically s ignificant difference in eradication of group A streptococci does raise add itional questions about shortened courses of macrolide therapy for this com mon infection.