Pneumococcal conjugate vaccine does not influence Staphylococcus aureus carriage in young children with acute otitis media

We investigated nasopharyngeal carriage of Streptococcus pneumoniae and Staphylococcus aureus among infants and young children with acute otitis media in a country where use of 7-valent pneumococcal conjugate vaccine (PCV7) has been progressively implemented. Among 1783 children enrolled, 60.8% carried S. pneumoniae, and 9% carried S. aureus. Among S. pneumoniae carriers, the rate of S. aureus carriage was 8.4%, compared with 9.9% among S. pneumoniae noncarriers. The rate of S. pneumoniae carriage in the PCV7-vaccinated population was lower (59.8%) than that observed in the nonvaccinated population (66.2%; P <.04). In contrast, in young children (age, < 2 years) with acute otitis media, our study suggests that the S. aureus carriage rate is not affected by PCV7 immunization (9.0% in vaccinated children vs. 8.7% in nonvaccinated children). Furthermore, in children aged > 1 year, the booster dose induces a sharp reduction in the carriage of vaccine serotypes of S. pneumoniae, without any change in S. aureus carriage.