EVIDENCE-BASED ANSWER
A short-term course of erythromycin, azithromycin, or clarithromycin is as effective as a long-term (2-week) erythromycin therapy in eradicating Bordetella pertussis from the nasopharynx (strength of recommendation [SOR]: A; based on one meta-analysis of randomized controlled trials [RCTs]). Evidence is insufficient to determine the benefit of antibiotic prophylaxis for pertussis contacts. However, due to high mortality and morbidity, prophylaxis is recommended for families who have an infant less than 6 months old (SOR: C; based on expert opinion).
CLINICAL COMMENTARY
Fewer doses and lower cost make compliance more likely
Marcia Warren, MD
Departments of Family and Community Medicine and Pediatrics, Baylor College of Medicine, Houston, Tex
I found this Clinical Inquiry on the treatment and prophylaxis of Bordetella pertussis invaluable as it addresses ease of dosing and cost, 2 things important in my pediatric community health practice with its inherent financial and social constraints. The alternatives suggested are easy to use and are as equally effective as the first-line therapy of erythromycin estolate, the long-term treatment recommended by the CDC and the AAP. These alternatives, clarithromycin and azithromycin, require either twice a day or a once a day dosing for 7 days or 3 days respectively, can be accommodated in busy households, thus promoting better compliance.
The cost of medication also relates to compliance. The cost difference between the first-line therapy and the alternative therapy is significant, and may be as much as $89. In an underinsured population, this out-of-pocket cost for the alternatives would prove prohibitive, resulting in decreased compliance. Where cost is not a great issue and concerns of compliance important, choosing the short-term treatment may be a preferable option. For the financially strapped, the 1-week regimen of erythromycin estolate would be preferable. The importance of counseling cannot be overstated in all dosing regimens, especially in those with a more difficult dosing schedule and in cases of prophylaxis in a household with an infant less than 6 months old.
Evidence summary
A 2005 Cochrane review of 11 RCTs and 1 quasi-randomized trial, with a total of 1720 adults and children, investigated several antibiotics for treatment and prophylaxis of pertussis. The outcome measures used to assess the efficacy of antibiotic treatment or prophylaxis vary between the trials and most of them did not report the immunization status of the participants. The Cochrane review included 1 meta-analysis of 3 studies with 252 participants, comparing azithromycin for 3 days, erythromycin estolate for 7 days, and clarithromycin for 7 days (short-term treatment) with erythromycin estolate for fourteen days (long-term treatment). The study showed equal efficacy in eradication of B pertussis from the nasopharynx of 99.2% to 97.7% (absolute risk reduction [ARR]=1.44%; 95% confidence interval [CI], –1.58 to 4.46). There were fewer side effects with the short-term treatment (32.1% vs 48.9%; ARR=16%; 95% CI, 7.84 to 25.84).1
A large, multicenter RCT of 477 children of 6 months to 16 years of age demonstrated that a 5-day treatment with azithromycin eradicated B pertussis from the nasopharynx as effectively as a 10-day course of erythromycin estolate.2 Similarly, trimethoprim/sulfamethoxazole proved as effective as erythromycin in eliminating B pertussis from the nasopharynx.