Streptococcus pneumoniae bacteremia in Southern California hospitalized children after implementation of pneumococcal conjugate vaccine

Abstract

The introduction of Streptococcus pneumoniae 7-valent conjugate vaccine has decreased pneumococcal infections in children. Recently a resurgence of invasive pneumococcal infections has been reported. Delineating populations at risk and microbiological changes responsible for this is important to develop new preventive strategies. We conducted a retrospective review of medical records of children hospitalized with pneumococcal bacteremia from July 1st 2005 through February 28th 2010 in a large tertiary care center in Southern California. We identified 74 subjects (mean age 5 yr; range 32 days to 21 yr and 2 mo) of which the majority (58.1%) had underlying medical conditions associated with increased risk for pneumococcal infections for whom pneumococcal polysaccharide vaccine is recommended after 2 yr of age. Seventy-seven isolates were recovered from 76 positive blood cultures; serotype was available for 57 isolates, 5 (6B, 14, 23F and two were 19F) were 7-valent conjugate vaccine isolates. Forty were included in the 23-valent polysaccharide vaccine. Nineteen (35.2%) were 19A. Pneumonia was common particularly among previously healthy children (74%). New vaccines, targeted against serotypes that have emerged following the introduction of the 7-valent conjugate vaccine and better utilization of existing vaccines in patients at risk should further decrease invasive pneumococcal disease.