title: Streptococcus agalactiae pulsed-field gel electrophoresis patterns cross capsular types.
abstract: Streptococcus agalactiae is a genetically diverse organism; when typed by pulsed-field gel electrophoresis (PFGE), multiple types appear within a single serotype. We tested whether S. agalactiae PFGE types correspond to a specific serotype within individuals, and different individuals from the same geographic area. A total of 872 S. agalactiae isolates from 152 healthy individuals were classified by PFGE and capsular serotype. Serotype V was the most homogeneous (Simpson's diversity index 0.54); and types III, II and Ib were mostly heterogeneous (Simpson's diversity index 0.90). Within an individual, isolates with the same PFGE patterns had identical capsular types, but across individuals the same PFGE types sometimes occurred in different serotypes. Capsular type alone is insufficient to define epidemiological relatedness. Although PFGE types appear to be a valid surrogate for capsular typing of isolates from the same individual, it is not a valid surrogate for serotype in isolates from different individuals.
authors.affiliation: Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI, USA.
authors.forename: P
authors.initials: P
authors.lastname: Pillai
authors.forename: U
authors.initials: U
authors.lastname: Srinivasan
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: S M
authors.initials: SM
authors.lastname: Borchardt
authors.forename: J
authors.initials: J
authors.lastname: Debusscher
authors.forename: C F
authors.initials: CF
authors.lastname: Marrs
authors.forename: B
authors.initials: B
authors.lastname: Foxman
mesh_terms: D000328:Adult; D016667:Bacterial Capsules / Q000276:immunology*; D015373:Bacterial Typing Techniques / Q000379:methods*; D016000:Cluster Analysis; D016172:DNA Fingerprinting / Q000379:methods*; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D008297:Male; D010641:Phenotype; D012703:Serotyping; D013292:Streptococcus agalactiae / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D055815:Young Adult
chemical_list: D004269:DNA, Bacterial