title: Pneumococcal carriage and serotype variation before and after introduction of pneumococcal conjugate vaccines in patients with acute otitis media in Switzerland.
abstract: Acute otitis media (AOM) is an important cause for antibiotic prescription within the paediatric population and Streptococcus pneumoniae is a major pathogen associated with AOM episodes. This study aimed at analysing the influence of the heptavalent and 13-valent pneumococcal conjugate vaccines (PCV7 and PCV13) on pneumococcal carriage and serotype distribution in AOM.
  
  
  
  Nasopharyngeal swabs (NPS) and middle ear fluid (MEF) were collected within a Swiss surveillance study of outpatients from all ages with AOM between 2004 and 2015, covering three vaccination eras (pre-PCV7, PCV7 and PCV13). Samples were cultured for pneumococcal identification, and the association of vaccine era with pneumococcal carriage was investigated by logistic regression analysis adjusting for sociodemographic factors.
  
  
  
  In total, 3300 NPS and 620 MEF were included in this study. The number of samples from patients with AOM dropped over vaccination eras and S. pneumoniae was less frequently isolated in the PCV13 era as compared to the other two eras. The latest (PCV13) vaccination era was independently associated with a reduced pneumococcal carriage within NPS (adjusted odds ratio 0.65, 95%-CI 0.45-0.94). Investigating serotype epidemiology, vaccine serotypes decreased significantly after the conjugate vaccine introductions with the exception of serotype 3. Within the non-PCV13 serotypes, a particular increase of serogroups 11, 15 and 23 was observed in both NPS and MEF.
  
  
  
  A substantial change in pneumococcal carriage and serotype epidemiology suggests an impact of the conjugate vaccines on pneumococcal AOM in Switzerland.
authors.affiliation: Institute for Infectious Diseases, University of Bern, Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Allemann
authors.affiliation: Institute for Infectious Diseases, University of Bern, Bern, Switzerland; Department of Microbiology, The Forsyth Institute, Cambridge, MA, USA; Department of General Internal Medicine, Inselspital, University Hospital Bern, University of Bern, Bern, Switzerland.
authors.forename: Pascal M
authors.initials: PM
authors.lastname: Frey
authors.affiliation: Institute for Infectious Diseases, University of Bern, Bern, Switzerland; Department of Microbiology, The Forsyth Institute, Cambridge, MA, USA; Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA.
authors.forename: Silvio D
authors.initials: SD
authors.lastname: Brugger
authors.affiliation: Institute for Infectious Diseases, University of Bern, Bern, Switzerland; Department of Infectious Diseases, Inselspital, University Hospital Bern, University of Bern, Bern, Switzerland. Electronic address: markus.hilty@ifik.unibe.ch.
authors.forename: Markus
authors.initials: M
authors.lastname: Hilty
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001431:Bacteriological Techniques; D002353:Carrier State / Q000453:epidemiology / Q000382:microbiology*; D002648:Child; D002675:Child, Preschool; D004432:Ear, Middle / Q000382:microbiology; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine / Q000008:administration & dosage*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009305:Nasopharynx / Q000382:microbiology; D010033:Otitis Media / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D015995:Prevalence; D012189:Retrospective Studies; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000302:isolation & purification; D013557:Switzerland / Q000453:epidemiology; D055815:Young Adult
chemical_list: C538862:13-valent pneumococcal vaccine; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines
keywords: Acute otitis media; Logistic regression; PCV13; PCV7; Pneumococcus