title: Nasopharyngeal carriage of Streptococcus pneumoniae and other bacteria in the 7th year after implementation of the pneumococcal conjugate vaccine in the Netherlands.
abstract: After introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) in the infant national immunization program (NIP) in the Netherlands in 2006, Streptococcus pneumoniae strains of the non-vaccine serotype 19A emerged and became the dominant serotype in carriage in children and their parents. Similar patterns were observed in other European countries and the United States. Increases in carriage rates of Staphylococcus aureus and non-typeable (NT) Haemophilus influenzae were also observed. After switching of PCV7 to 10-valent vaccine (PCV10) in 2011, a new carriage surveillance study was performed in the winter of 2012/2013. Nasopharyngeal carriage of S. pneumoniae, H. influenzae, S. aureus, and Moraxella catarrhalis was determined by conventional culture in 330 PCV10-vaccinated 11-month-old children, 330 PCV7-vaccinated 24-month-old children, and their parents. Carriage prevalence was compared with similar carriage studies conducted in 2005, 2009, and 2010/2011. Although serotype 19A remained the most frequently carried pneumococcal serotype in children, prevalence of 19A significantly declined in PCV7-vaccinated 24-month-old children (14% to 8%, p=0.01), but less in PCV10-vaccinated 11-month-old children (12% to 9%, p=0.31). Carriage of H. influenzae remained stable at an elevated level (65% in 11-month-olds and 69% in 24-month-olds), while the carriage of S. aureus returned to pre-PCV7 levels in 11-month-old children (14% in 2010/2011 to 7% in 2012/2013), but not in 24-month-olds (remained at 7%). Our results might indicate a new balance between replacing non-vaccine pneumococcal serotypes and other potential pathogenic bacteria in nasopharyngeal carriage. Carriage studies are valuable tools in assessing vaccine effects on pathogens circulating in the population, for evaluation of PCV impact, and in predicting changes in respiratory and invasive disease.
authors.affiliation: Wilhelmina Children's Hospital, University Medical Center, Utrecht, The Netherlands; Spaarne Gasthuis Academy (Former Linneaus Institute), Hoofddorp, The Netherlands.
authors.forename: Astrid A T M
authors.initials: AATM
authors.lastname: Bosch
authors.affiliation: Spaarne Gasthuis Academy (Former Linneaus Institute), Hoofddorp, The Netherlands.
authors.forename: Marlies A
authors.initials: MA
authors.lastname: van Houten
authors.affiliation: Regional Laboratory of Public Health, Haarlem, The Netherlands.
authors.forename: Jacob P
authors.initials: JP
authors.lastname: Bruin
authors.affiliation: National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
authors.forename: Alienke J
authors.initials: AJ
authors.lastname: Wijmenga-Monsuur
authors.affiliation: Wilhelmina Children's Hospital, University Medical Center, Utrecht, The Netherlands.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Trzciński
authors.affiliation: Wilhelmina Children's Hospital, University Medical Center, Utrecht, The Netherlands.
authors.forename: Debby
authors.initials: D
authors.lastname: Bogaert
authors.affiliation: National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
authors.forename: Nynke Y
authors.initials: NY
authors.lastname: Rots
authors.affiliation: Wilhelmina Children's Hospital, University Medical Center, Utrecht, The Netherlands. Electronic address: L.Sanders@umcutrecht.nl.
authors.forename: Elisabeth A M
authors.initials: EAM
authors.lastname: Sanders
mesh_terms: D000328:Adult; D002353:Carrier State / Q000382:microbiology*; D002675:Child, Preschool; D005260:Female; D006193:Haemophilus influenzae / Q000302:isolation & purification; D000069443:Heptavalent Pneumococcal Conjugate Vaccine / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D017589:Immunization Programs; D007223:Infant; D008297:Male; D001936:Moraxella catarrhalis / Q000302:isolation & purification; D009305:Nasopharynx / Q000382:microbiology*; D009426:Netherlands; D018571:Sentinel Surveillance; D065288:Serogroup; D013211:Staphylococcus aureus / Q000302:isolation & purification; D013296:Streptococcus pneumoniae / Q000302:isolation & purification*
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine
keywords: Haemophilus influenzae; Moraxella catarrhalis; NL40288.094.12; NTR3614; Nasopharyngeal carriage; Pneumococcal conjugate vaccination (PCV); Staphylococcus aureus; Streptococcus pneumoniae