title: Nasopharyngeal carriage, serotype distribution and antimicrobial resistance of Streptococcus pneumoniae among children from Brazil before the introduction of the 10-valent conjugate vaccine.
abstract: BACKGROUND
  Streptococcus pneumoniae remains a major cause of childhood morbidity and mortality worldwide. Nasopharyngeal colonization plays an important role in the development and transmission of pneumococcal diseases, and infants and young children are considered to be the main reservoir of this pathogen. The aim of this study was to evaluate the rates and characteristics associated with nasopharyngeal carriage, the distribution of serotypes and the antimicrobial resistance profiles of Streptococcus pneumoniae among children in a large metropolitan area in Brazil before the introduction of the 10-valent pneumococcal conjugate vaccine.
  
  
  METHODS
  Between March and June 2010, nasopharyngeal swabs were collected from 242 children aged <6 years attending one day care center and the emergency room of a pediatric hospital. Pneumococcal isolates were identified by conventional methods and serotypes were determined by a sequential multiplex PCR assay and/or the Quellung reaction. The antimicrobial susceptibilities of the pneumococci were assessed by the disk diffusion method. MICs for erythromycin and penicillin were also performed. Erythromycin resistance genes were investigated by PCR.
  
  
  RESULTS
  The overall colonization rate was 49.2% and it was considerably higher among children in the day care center. Pneumococcal carriage was more common among day care attenders and cohabitants with young siblings. The most prevalent serotypes were 6B, 19F, 6A, 14, 15C and 23F, which accounted for 61.2% of the isolates. All isolates were susceptible to clindamycin, levofloxacin, rifampicin and vancomycin. The highest rate of non-susceptibility was observed for sulphamethoxazole-trimethoprim (51.2%). Penicillin non-susceptible pneumococci (PNSP) accounted for 27.3% of the isolates (MICs of 0.12-4 μg/ml). Penicillin non-susceptibility was strongly associated with serotypes 14 and 23F. Hospital attendance and the presence of respiratory or general symptoms were frequently associated with PNSP carriage. The two erythromycin-resistant isolates (MICs of 2 and 4 μg/ml) belonged to serotype 6A, presented the M phenotype and harbored the mef(A/E) gene.
  
  
  CONCLUSIONS
  Correlations between serotypes, settings and penicillin non-susceptibility were observed. Serotypes coverage projected for the 10-valent pneumococcal conjugate vaccine was low (45.5%), but pointed out the potential reduction of PNSP nasopharyngeal colonization by nearly 20%.
authors.affiliation: Instituto Biomédico, Universidade Federal Fluminense, Niterói, RJ, Brazil. fpgneves@vm.uff.br
authors.forename: Felipe Piedade Gonçalves
authors.initials: FP
authors.lastname: Neves
authors.forename: Tatiana Castro Abreu
authors.initials: TC
authors.lastname: Pinto
authors.forename: Mariane Alves
authors.initials: MA
authors.lastname: Corrêa
authors.forename: Roberta
authors.initials: R
authors.lastname: dos Anjos Barreto
authors.forename: Laís
authors.initials: L
authors.lastname: de Souza Gouveia Moreira
authors.forename: Havana Gomes
authors.initials: HG
authors.lastname: Rodrigues
authors.forename: Claudete Araújo
authors.initials: CA
authors.lastname: Cardoso
authors.forename: Rosana Rocha
authors.initials: RR
authors.lastname: Barros
authors.forename: Lúcia Martins
authors.initials: LM
authors.lastname: Teixeira
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001938:Brazil; D002353:Carrier State / Q000382:microbiology*; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests; D009305:Nasopharynx / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*
chemical_list: C538863:10-valent pneumococcal vaccine; D000900:Anti-Bacterial Agents; D022242:Pneumococcal Vaccines