title: Genotypic diversity and serotype distribution of group B streptococcus isolated from women before and after delivery.
abstract: BACKGROUND
  Most studies of the dynamics of maternal group B Streptococcus (GBS) colonization have relied on capsular serotyping to define GBS acquisition or loss. Newer molecular methods that distinguish GBS clones may expand our knowledge and influence vaccination strategies. We used multilocus sequence typing (MLST) and GBS capsular gene cluster (cps) genotyping to investigate the dynamics of perinatal GBS colonization.
  
  
  METHODS
  A total of 338 GBS isolates obtained from 212 colonized women who were enrolled in a prior prospective cohort study were serotyped and genotyped by MLST and cps typing before (visit 1) and 6 weeks after (visit 2) delivery.
  
  
  RESULTS
  Of the 212 women, 126 were colonized at both visits, whereas 66 lost and 20 acquired GBS by visit 2. MLST of the 338 strains identified 29 sequence types marking distinct bacterial clones. A change in sequence type or cps and serotype occurred in 23 (18.3%) of the 126 women who were colonized at both visits. Specific sequence types were associated with GBS loss and persistence. Older maternal age and exclusive intrapartum antibiotic use were associated with persistent colonization.
  
  
  CONCLUSIONS
  Although most GBS-positive pregnant women were stably colonized during the peripartum period, we detected changes in capsule expression and recolonization with antigenically distinct GBS clones over time by applying MLST. Combining the epidemiologic and molecular typing data revealed host factors and clones associated with persistent colonization, as well as a clone that was more readily lost. This knowledge is useful for the development of prevention and intervention strategies to reduce the likelihood of maternal GBS colonization.
authors.affiliation: Microbial Evolution Laboratory, National Food Safety and Toxicology Center, Michigan State University, East Lansing, Michigan, USA.
authors.forename: Shannon D
authors.initials: SD
authors.lastname: Manning
authors.forename: Maggi A
authors.initials: MA
authors.lastname: Lewis
authors.forename: A Cody
authors.initials: AC
authors.lastname: Springman
authors.forename: Erica
authors.initials: E
authors.lastname: Lehotzky
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Whittam
authors.forename: H Dele
authors.initials: HD
authors.lastname: Davies
mesh_terms: D000328:Adult; D016667:Bacterial Capsules / Q000235:genetics; D002170:Canada; D002353:Carrier State / Q000382:microbiology*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D012007:Rectum / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D012703:Serotyping; D013292:Streptococcus agalactiae / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D014621:Vagina / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial