title: Nasopharyngeal flora in children with acute otitis media before and after implementation of 7 valent pneumococcal conjugate vaccine in France.
abstract: BACKGROUND
  Several studies have investigated the impact of 7-valent pneumococcal conjugate vaccine (PCV7) on pneumococcal (Sp) and staphylococcal (Sa) nasopharyngeal (NP) carriage. Few have investigated the impact on Haemophilus influenzae (Hi) and Moraxella catarrhalis (Mc) carriage. We aimed to compare the NP carriage rates in young children with acute otitis media (AOM) before and after PCV7 implementation in France.
  
  
  METHODS
  Prior to PCV7 implementation, we performed 4 successive randomized trials with NP samples. These studies compared several antibiotic regimens for treating AOM in young children (6 to 30 months). After PCV7 implementation, to assess the impact of the vaccination program on NP flora, young children with AOM were enrolled in a prospective surveillance study. In each study, we obtained an NP sample to analyze the carriage rates of Sp, Hi, Mc and Sa and the factors influencing the carriage. Standardized history and physical examination findings were recorded; the methods used for NP swabs (sampling and cultures) were the same in all studies.
  
  
  RESULTS
  We enrolled 4,405 children (mean age 13.9 months, median 12.8). Among the 2,598 children enrolled after PCV7 implementation, 98.3% were vaccinated with PCV7. In comparing the pre- and post-PCV7 periods, we found a slight but non-significant decrease in carriage rates of pneumococcus (AOR = 0.85 [0.69;1.05]), H. influenzae (AOR = 0.89 [0.73;1.09]) and S. aureus (AOR = 0.92 [0.70;1.19]). By contrast, the carriage rate of M. catarrhalis increased slightly but not significantly between the 2 periods (AOR = 1.08 [0.95;1.2]). Among Sp carriers, the proportion of PCV7 vaccine types decreased from 66.6% to 10.7% (P < 0.001), penicillin intermediate-resistant strains increased from 30.3% to 43.4% (P < 0.001), and penicillin-resistant strains decreased greatly from 22.8% to 3.8% (P < 0.001). The proportion of Hi ß-lactamase-producing strains decreased from 38.6% to 17.1% (P < 0.001).
  
  
  CONCLUSIONS
  The carriage rates of otopathogen species (Sp, Hi, Mc) and Sa did not significantly change in children with AOM after PCV7 implementation in France. However, we observed significant changes in carriage rates of PCV7 vaccine serotypes and penicillin non-susceptible Sp.
authors.affiliation: ACTIV, Association Clinique Thérapeutique Infantile du Val de Marne, 27 rue Inkermann, F94100 Saint Maur des Fossés, France. robert.cohen@wanadoo.fr
authors.forename: Robert
authors.initials: R
authors.lastname: Cohen
authors.forename: Edouard
authors.initials: E
authors.lastname: Bingen
authors.forename: Corinne
authors.initials: C
authors.lastname: Levy
authors.forename: Franck
authors.initials: F
authors.lastname: Thollot
authors.forename: Michel
authors.initials: M
authors.lastname: Boucherat
authors.forename: Véronique
authors.initials: V
authors.lastname: Derkx
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Varon
mesh_terms: D058448:Biota; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology*; D002675:Child, Preschool; D005260:Female; D005602:France; D006193:Haemophilus influenzae / Q000302:isolation & purification; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007223:Infant; D008297:Male; D001936:Moraxella catarrhalis / Q000302:isolation & purification; D009305:Nasopharynx / Q000382:microbiology*; D010033:Otitis Media / Q000382:microbiology*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D015995:Prevalence; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic; D013211:Staphylococcus aureus / Q000302:isolation & purification; D013296:Streptococcus pneumoniae / Q000302:isolation & purification
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines