Impact of pneumococcal conjugate vaccine and of reduction of antibiotic use on nasopharyngeal carriage of nonsusceptible pneumococci in children with acute otitis media.

Background: Penicillin resistance among pneumococci has increased in the past 15 years. The implementation of widespread vaccination with the heptavalent pneumococcal conjugate vaccine (PCV7) and the reduction of inappropriate antibiotic use could help reduce antibiotic resistance.

Methods: Between September 2001 and June 2004, 89 pediatricians distributed throughout France took part in this prospective study. We obtained 1906 nasopharyngeal swabs for culture from children aged 6 to 24 months with acute otitis media (AOM). At the same time as PCV7 was introduced into the routine immunization schedule, a plan to promote judicious antibiotic use was established. We recorded the frequency of antibiotic use, as well as the dates of immunization with PCV7.

Results: The proportion of PCV7-vaccinated children (> or =1 dose) increased from 8.2% (year 1) to 61.4% (year 3). The proportion of children who received antibiotics within 3 months before enrollment decreased from 51.8% in year 1 to 40.9% in year 3 (P < 0.001). Overall pneumococcal carriage and carriage of PCV7 serotypes decreased during the 3-year period by 16% (P < 0.001) and 35% (P < 0.001), respectively. Rates of highly penicillin resistant strains (PRP) decreased yearly: 15.4%, 10.6%, 6.7% (P < 0.001), respectively. Risks for PRP carriage were 4.2% for immunized children who had not received antibiotics, 8.6% for those vaccinated who also had received antibiotics, 10.3% for unimmunized children who had not received antibiotics, and 16.2% for unimmunized children who had received antibiotics (P < 0.001).

Conclusion: Implementation of PCV7, combined with a reduction in antibiotic use, in a country with a high prevalence of antibiotic-resistant pneumococci appears to have a strong impact on the carriage of penicillin nonsusceptible pneumococci in children with AOM.