title: Genetic analysis of diverse disease-causing pneumococci indicates high levels of diversity within serotypes and capsule switching.
abstract: We have used multilocus sequence typing (MLST) and serotyping to build a phylogenetic framework for pneumococcal disease isolates in Scotland that provides a snapshot of the relationships between capsular type and genotype. The results show that while the MLST type correlates with the serotype, isolates within a serotype can belong to a number of individual clonal complexes or sequence types (STs). We also show that isolates of the same ST can express different capsular polysaccharides, i.e., display capsular switching, and that this phenomenon is observed both for capsular types commonly isolated from patients with invasive disease and for serogroups less commonly isolated from patients with invasive disease but which may commonly be carried asymptomatically in the human nasopharynx.
authors.affiliation: Institute of Biomedical and Life Sciences, Division of Infection & Immunity, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom. T.Mitchell@bio.gla.ac.uk
authors.forename: Johanna M C
authors.initials: JM
authors.lastname: Jefferies
authors.forename: Andrew
authors.initials: A
authors.lastname: Smith
authors.forename: Stuart C
authors.initials: SC
authors.lastname: Clarke
authors.forename: Chris
authors.initials: C
authors.lastname: Dowson
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Mitchell
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016667:Bacterial Capsules / Q000235:genetics* / Q000378:metabolism; D015373:Bacterial Typing Techniques; D002648:Child; D002675:Child, Preschool; D014644:Genetic Variation; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000382:microbiology*; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000235:genetics*