title: Emergence of a serotype 1 Streptococcus pneumoniae lineage colonising healthy children in Portugal in the seven-valent conjugate vaccination era.
abstract: Serotype 1 pneumococci are rarely isolated from carriers, but are an important cause of pneumococcal invasive disease in many regions of the world. This report describes the emergence and expansion of a single serotype 1 lineage (characterised by multilocus sequence type 306) among healthy carriers attending day-care centres in Portugal. The prevalence of serotype 1 strains among all pneumococci increased from 0% in 2001 and 2002, to 0.4% in 2003, and 3.1% in 2006. These observations paralleled the introduction and increased use of the seven-valent pneumococcal conjugate vaccine in the study group, suggesting a direct relationship between these events.
authors.affiliation: Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
authors.forename: S
authors.initials: S
authors.lastname: Nunes
authors.forename: R
authors.initials: R
authors.lastname: Sá-Leão
authors.forename: L C
authors.initials: LC
authors.lastname: Pereira
authors.forename: H
authors.initials: H
authors.lastname: de Lencastre
mesh_terms: D015373:Bacterial Typing Techniques; D002353:Carrier State / Q000382:microbiology*; D002648:Child; D002675:Child, Preschool; D005838:Genotype; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007223:Infant; D022401:Meningococcal Vaccines / Q000276:immunology*; D011008:Pneumococcal Infections / Q000382:microbiology*; D022242:Pneumococcal Vaccines / Q000276:immunology*; D011174:Portugal; D017422:Sequence Analysis, DNA; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022401:Meningococcal Vaccines; D022242:Pneumococcal Vaccines