title: Impact of heptavalent pneumococcal conjugate vaccine on nasopharyngeal carriage of penicillin-resistant Streptococcus pneumoniae among day-care center attendees in central Greece.
abstract: BACKGROUND
  In Greece, the heptavalent pneumococcal conjugate vaccine (PCV7) became available in October 2004 and it was incorporated into the national immunization schedule in January 2006.
  
  
  METHODS
  In February 2005, a yearly surveillance of the nasopharyngeal colonization with Streptococcus pneumoniae in children attending day-care centers in Central Greece began.
  
  
  RESULTS
  Between February 2005 and May 2007, nasopharyngeal cultures were obtained from 1829 children aged 13-76 months (median age, 47 months). The proportion of attendees vaccinated with > or =1 doses of PCV7 increased from 13% (2005) to 33% (2006) and to 70% (2007); 98% had been immunized on toddler catch-up schedules. Among vaccinated carriers, the proportion of PCV7 serotypes decreased from 33% (2005) to 29% (2006) and to 8.6% (2007) (chi for trend, P < 0.001), the proportion of PCV7-related serotypes increased from 13% (2005) to 26% (2006) and to 28% (2007) (P = 0.16), whereas the proportion of non-PCV7 serotypes was 48% in 2005, 31% in 2006, and 55% in 2007 (P = 0.17). The proportion of PCV7 serotypes declined also among unvaccinated carriers. The carriage of serotype 19A did not increase. Among vaccinated carriers, the rate of highly penicillin-resistant isolates decreased from year 1 to year 3, respectively, 11%, 7.7%, and 0.6% (P = 0.001), whereas the proportion of penicillin-intermediate pneumococci was 13% in 2005, 23% in 2006, and 26% in 2007 (P = 0.22).
  
  
  CONCLUSIONS
  In Central Greece, widespread PCV vaccination was followed by a significant reduction of carriage of highly penicillin-resistant pneumococci. The frequency of penicillin-intermediate isolates did not change significantly among vaccinated carriers.
authors.affiliation: Department of Pediatrics, University of Thessaly, School of Medicine, General University Hospital, Larissa, Greece.
authors.forename: Ioanna N
authors.initials: IN
authors.lastname: Grivea
authors.forename: Maria
authors.initials: M
authors.lastname: Panagiotou
authors.forename: Alexandra G
authors.initials: AG
authors.lastname: Tsantouli
authors.forename: George A
authors.initials: GA
authors.lastname: Syrogiannopoulos
mesh_terms: D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology*; D002648:Child; D002656:Child Day Care Centers; D002675:Child, Preschool; D005260:Female; D006115:Greece / Q000453:epidemiology; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007223:Infant; D008297:Male; D022401:Meningococcal Vaccines / Q000276:immunology*; D008826:Microbial Sensitivity Tests; D010403:Penicillin Resistance; D010614:Pharynx / Q000382:microbiology*; D022242:Pneumococcal Vaccines / Q000276:immunology*; D015995:Prevalence; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification*
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022401:Meningococcal Vaccines; D022242:Pneumococcal Vaccines