title: Group B streptococcus serotype prevalence in reproductive-age women at a tertiary care military medical center relative to global serotype distribution.
abstract: BACKGROUND
  Group B Streptococcus (GBS) serotype (Ia, Ib, II-IX) correlates with pathogen virulence and clinical prognosis. Epidemiological studies of seroprevalence are an important metric for determining the proportion of serotypes in a given population. The purpose of this study was to evaluate the prevalence of individual GBS serotypes at Madigan Healthcare System (Madigan), the largest military tertiary healthcare facility in the Pacific Northwestern United States, and to compare seroprevalences with international locations.
  
  
  METHODS
  To determine serotype distribution at Madigan, we obtained GBS isolates from standard-of-care anogenital swabs from 207 women of indeterminate gravidity between ages 18-40 during a five month interval. Serotype was determined using a recently described molecular method of polymerase chain reaction by capsular polysaccharide synthesis (cps) genes associated with pathogen virulence.
  
  
  RESULTS
  Serotypes Ia, III, and V were the most prevalent (28%, 27%, and 17%, respectively). A systematic review of global GBS seroprevalence, meta-analysis, and statistical comparison revealed strikingly similar serodistibution at Madigan relative to civilian-sector populations in Canada and the United States. Serotype Ia was the only serotype consistently higher in North American populations relative to other geographic regions (p < 0.005). The number of non-typeable isolates was significantly lower in the study (p < 0.005).
  
  
  CONCLUSIONS
  This study establishes PCR-based serotyping as a viable strategy for GBS epidemiological surveillance. Our results suggest that GBS seroprevalence remains stable in North America over the past two decades.
authors.affiliation: Department of Clinical Investigation, Madigan Healthcare System, 9040 Reid St,, Tacoma, WA 98431, USA.
authors.forename: Danielle L
authors.initials: DL
authors.lastname: Ippolito
authors.forename: Wesley A
authors.initials: WA
authors.lastname: James
authors.forename: Deborah
authors.initials: D
authors.lastname: Tinnemore
authors.forename: Raywin R
authors.initials: RR
authors.lastname: Huang
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Dehart
authors.forename: Julie
authors.initials: J
authors.lastname: Williams
authors.forename: Mark A
authors.initials: MA
authors.lastname: Wingerd
authors.forename: Samandra T
authors.initials: ST
authors.lastname: Demons
mesh_terms: D000293:Adolescent; D000328:Adult; D002170:Canada / Q000453:epidemiology; D005260:Female; D006772:Hospitals, Military / Q000706:statistics & numerical data*; D006801:Humans; D015205:Northwestern United States / Q000453:epidemiology; D015995:Prevalence; D012703:Serotyping; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013292:Streptococcus agalactiae / Q000145:classification* / Q000302:isolation & purification; D055815:Young Adult