OBJECTIVES-The goals were to assess serial changes in Streptococcus pneumoniae serotypes and antibiotic resistance in young children and to evaluate whether risk factors for carriage have been altered by heptavalent pneumococcal conjugate vaccine (PCV7).METHODS-Nasopharyngeal specimens and questionnaire/medical record data were obtained from children 3 months to <7 years of age in primary care practices in 16 Massachusetts communities during the winter seasons of 2000-2001 and 2003-2004 and in 8 communities in 2006-2007. Antimicrobial susceptibility testing and serotyping were performed with S pneumoniae isolates.RESULTS-We collected 678, 988, and 972 specimens during the sampling periods in 2000-2001, 2003-2004, and 2006-2007, respectively. Carriage of non-PCV7 serotypes increased from 15% to 19% and 29% (P < .001), with vaccine serotypes decreasing to 3% of carried serotypes in [2006][2007]. The relative contribution of several non-PCV7 serotypes, including 19A, 35B, and 23A, increased across sampling periods. By 2007, commonly carried serotypes included 19A (16%), 6A (12%), 15B/C (11%), 35B (9%), and 11A (8%), and high-prevalence serotypes seemed to have greater proportions of penicillin nonsusceptibility. In multivariate models, common predictors of pneumococcal carriage, such as child care attendance, upper respiratory tract infection, and the presence of young siblings, persisted. CONCLUSIONS-The virtual disappearance of vaccine serotypes in S pneumoniae carriage has occurred in young children, with rapid replacement with penicillin-nonsusceptible nonvaccine serotypes, particularly 19A and 35B. Except for the age group at highest risk, previous predictors of NIH Public Access Author ManuscriptPediatrics. Author manuscript; available in PMC 2010 July 1. Published in final edited form as:Pediatrics. WHAT's KNOWN ON THIS SUBJECTIPD rates decreased after the release of PCV7 but now are increasing because of non-PCV7 isolates. We showed previously that serial collection of colonizing strains can forecast increases in non-PCV7 isolates that may be sources of later disease. WHAT THIS STUDY ADDSThis study shows rapid, nearly complete replacement of colonizing PCV7 strains by non-PCV7 strains in young children. Some previously common risk factors for carriage have changed, which suggests that serotype changes may be challenging our previous knowledge of pneumococcal transmission.The heptavalent pneumococcal conjugate vaccine (PCV7) has reduced substantially the rates of invasive pneumococcal disease (IPD) in children. [1][2][3][4][5] It also has produced modest decreases in rates of common childhood noninvasive diseases such as otitis media. 6 Through herd immunity, it has reduced rates of IPD in adults and immunocompromised hosts, 1,2,7 including disease among HIV-positive individuals. 8The ability of this vaccine to maintain reductions in IPD rates has been questioned, however, because nonvaccine serotypes have increased in the absence of vaccine serotypes. [9][10][11] Evidence is mounting that nonva...

Routine surveillance for MRSA in ICUs allowed earlier initiation of contact isolation precautions and was associated with large and statistically significant reductions in the incidence of MRSA bacteremia in the ICUs and hospital wide. In contrast, no similar decrease was attributable to the other infection control interventions.

Our study does not support a causal association between early exposure to mercury from thimerosal-containing vaccines and immune globulins and deficits in neuropsychological functioning at the age of 7 to 10 years.