Bacteremia in Children 3 to 36 Months Old After Introduction of Conjugated Pneumococcal Vaccines

BACKGROUND AND OBJECTIVES: In June 2010, Kaiser Permanente Northern California replaced all abstract 7-valent pneumococcal conjugate vaccine (PCV7) vaccines with the 13-valent pneumococcal conjugate vaccine (PCV13). Our objectives were to compare the incidence of bacteremia in children 3 to 36 months old by 3 time periods: pre-PCV7, post-PCV7/ pre-PCV13, and post-PCV13. METHODS: We designed a retrospective review of the electronic medical records of all blood cultures collected on children 3 to 36 months old at Kaiser Permanente Northern California from September 1, 1998 to August 31, 2014 in outpatient clinics, in emergency departments, and in the first 24 hours of hospitalization. RESULTS: During the study period, 57 733 blood cultures were collected in the population of children 3 to 36 months old. Implementation of routine immunization with the pneumococcal conjugate vaccine resulted in a 95.3% reduction of Streptococcus pneumoniae bacteremia, decreasing from 74.5 to 10 to 3.5 per 100 000 children per year by the postPCV13 period. As pneumococcal rates decreased, Escherichia coli, Salmonella spp, and Staphylococcus aureus caused 77% of bacteremia. Seventy-six percent of all bacteremia in the post-PCV13 period occurred with a source. CONCLUSIONS: In the United States, routine immunizations have made bacteremia in the previously healthy toddler a rare event. As the incidence of pneumococcal bacteremia has decreased, E coli, Salmonella spp, and S aureus have increased in relative importance. New guidelines are needed to approach the previously healthy febrile toddler in the outpatient setting.