Enhanced invasiveness of bovine-derived neonatal sequence type 17 group B streptococcus is independent of capsular serotype

Clin Infect Dis. 2006 Apr 1;42(7):915-24. doi: 10.1086/500324. Epub 2006 Feb 22.


Background: A defined geographical area (Oxford, United Kingdom) was investigated for the role of group B Streptococcus (GBS) as a human pathogen.

Methods: GBS carriage in pregnant women and invasive disease in neonates and adults >60 years of age was studied over a 3-year period. Multilocus sequence typing and capsular serotyping were used to study 369 isolates of GBS from carriage in pregnant women (n=190) and invasive disease in neonates (n=109) and adults >60 years of age (n=70).

Results: A total of 20.3% of pregnant women carried GBS. Invasive GBS disease occurred at a rate of 0.9 cases per 1000 live births and 11 cases per 100,000 population >60 years of age per annum. Four sequence types (STs) (ST-17, ST-19, ST-23, and ST-1) that were identified with use of multilocus sequence typing accounted for >50% of carried and invasive strains. A single sequence type (ST-17), previously shown to be phylogenetically of bovine origin, was significantly associated with increased invasiveness in neonates (P=.00002), and this was independent of capsular serotype III. In contrast, among adults >60 years of age, no STs exhibited increased invasiveness, compared with STs carried in pregnant women.

Conclusions: Enhanced invasiveness associated with ST-17 is specific to neonates and is independent of capsular serotype.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Animals
  • Bacterial Capsules / classification*
  • Carrier State / microbiology*
  • Cattle / microbiology*
  • Female
  • Humans
  • Infant, Newborn
  • Male
  • Middle Aged
  • Pregnancy
  • Serotyping
  • Streptococcal Infections / epidemiology*
  • Streptococcus agalactiae / classification*
  • Streptococcus agalactiae / isolation & purification*
  • Vagina / microbiology