title: Risk factors for serotype 19A carriage after introduction of 7-valent pneumococcal vaccination.
abstract: BACKGROUND
  After the implementation of 7-valent pneumococcal conjugate vaccine (PCV7), in several countries, serotype 19A is now the serotype most frequently involved in pneumococcal diseases and carriage. To determine factors potentially related to 19A nasopharyngeal (NP) carriage we analyzed data from an ongoing prospective French national surveillance study of pneumococcal NP carriage in young children.
  
  
  METHODS
  NP swabs were obtained from children aged 6 to 24 months, either during routine check-ups with normal findings, or when they presented with acute otitis media (AOM). The swabs were sent for analysis to the French National Reference Centre for Pneumococci. Factors influencing pneumococcal carriage and carriage of penicillin non-susceptible (PNSP), 19A and PNS-19A were investigated by multivariate logistic regression.
  
  
  RESULTS
  From 2006 to 2009, 66 practitioners enrolled 3507 children (mean age 13.6 months), of whom, 98.3% of children had been vaccinated with PCV7 and 33.4% of children attended daycare centres (DCC). Serotype 19A was found in 10.4% of the overall population, 20.5% of S. pneumoniae carriers (n = 1780) and 40.8% of PNSP carriers (n = 799). Among 19A strains, 10.7% were penicillin-susceptible, 80% intermediate and 9.3% fully resistant. Logistic regression analysis showed that the main factors associated with PNSP carriage were AOM (OR = 3.09, 95% CI [2.39;3.98]), DCC (OR = 1.70, 95% CI [1.42;2.03]), and recent antibiotic use (OR = 1.24, 95% CI [1.05;1.47]. The main factors predictive of 19A carriage were recent antibiotic use (OR = 1.81, 95% CI [1.42;2.30]), AOM (OR = 1.67, 95% CI [1.11;2.49]), DCC (OR = 1.56, 95% CI [1.21;2.2] and young age, <12 months (OR = 1.51, 95% CI [1.16;1.97]).
  
  
  CONCLUSIONS
  In a population of children aged from 6 to 24 months with a high rate of PCV7 vaccination coverage, we found that antibiotic exposure, DCC attendance and AOM were linked to 19A carriage.
authors.affiliation: Department of Microbiology, CHI Créteil, France. robert.cohen@wanadoo.fr
authors.forename: Robert
authors.initials: R
authors.lastname: Cohen
authors.forename: Corinne
authors.initials: C
authors.lastname: Levy
authors.forename: Eric
authors.initials: E
authors.lastname: Bonnet
authors.forename: Franck
authors.initials: F
authors.lastname: Thollot
authors.forename: Michel
authors.initials: M
authors.lastname: Boucherat
authors.forename: Bernard
authors.initials: B
authors.lastname: Fritzell
authors.forename: Véronique
authors.initials: V
authors.lastname: Derkx
authors.forename: Edouard
authors.initials: E
authors.lastname: Bingen
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Varon
mesh_terms: D002353:Carrier State / Q000453:epidemiology / Q000382:microbiology*; D016022:Case-Control Studies; D024881:Drug Resistance, Bacterial; D005260:Female; D005602:France / Q000453:epidemiology; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D009296:Nasal Cavity / Q000382:microbiology; D010033:Otitis Media / Q000453:epidemiology / Q000382:microbiology; D010406:Penicillins / Q000494:pharmacology; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000382:microbiology* / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000276:immunology*; D012307:Risk Factors; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000276:immunology*
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D010406:Penicillins; D022242:Pneumococcal Vaccines