Background: The increasing rate of treatment failure with penicillin and other beta-lactam antibiotics in pharyngotonsillitis caused by group A beta-hemolytic streptococci (GABHS) has prompted the search for alternative antimicrobials. Both clindamycin and amoxicillin/clavulanic acid have excellent clinical activity in pharyngotonsillitis.
Objective: This study compared the clinical and bacteriologic efficacy and tolerability of oral clindamycin with those of oral amoxicillin/clavulanic acid in the outpatient treatment of acute recurrent GABHS pharyngotonsillitis.
Methods: This was an international, multicenter, randomized, investigator-blinded, prospective study in patients with acute recurrent pharyngotonsillitis. Recurrence was defined as > or =2 episodes of documented pharyngeal and/or tonsillar infection within the 12 months before the study. A rapid diagnostic test for GABHS was performed before initiating therapy, and positive results were confirmed by pharyngotonsillar culture. Patients were randomly assigned to receive oral clindamycin 300 mg BID or oral amoxicillin/clavulanic acid 1 g BID for 10 days. Culture was repeated on day 12. The primary study end points were clinical and bacteriologic efficacy assessed on day 12, and clinical and bacteriologic recurrence rates assessed at a visit taking place up to 3 months after the completion of treatment. Tolerability was the secondary end point.
Results: Seven hundred seventy-four patients with acute, recurrent GABHS pharyngotonsillitis were enrolled in the study (mean age, 28 years; age range, 12-60 years). Five hundred forty-two patients (272 clindamycin, 270 amoxicillin/clavulanic acid) were clinically evaluable at day 12. Four hundred ninety-four patients were bacteriologically evaluable, and the safety population included 772 patients. There were no significant differences between groups at baseline. In terms of clinical efficacy at day 12, 252/272 (92.6%) patients in the clindamycin group and 230/270 (85.2%) patients in the amoxicillin/clavulanic acid group were considered cured (P < 0.003). At day 12, bacteriologic eradication was achieved in 237/242 (97.9%) and 238/252 (94.4%) patients in the respective treatment groups (P = NS). No clinical response was observed in the absence of bacteriologic eradication. At 3-month follow-up, clinical cure was achieved in 267/280 (95.4%) patients in the clindamycin group and 267/280 (95.7%) patients in the amoxicillin/clavulanic acid group (P = NS); bacteriologic eradication was observed in 235 (99.2%) and 237 (99.6%) of the respective treatment groups (P = NS). Both treatments were well tolerated. Adverse events were reported in 53/384 (13.8%) patients in the clindamycin group and 41/390 (10.5%) patients in the amoxicillin/clavulanic acid group. The most commonly reported adverse events involved the digestive system (mainly diarrhea), occurring in 33 (8.6%) and 22 (5.6%) patients in the respective treatment groups.
Conclusions: In this study in patients with acute recurrent GABHS pharyngotonsillitis, oral clindamycin 300 mg BID and oral amoxicillin/clavulanic acid 1 g BID achieved comparable rates of bacteriologic eradication at 12 days and 3 months and comparable clinical cure rates at 3 months. Patients who received clindamycin had significantly greater clinical cure rates at 12 days. Both regimens were well tolerated.