Enhanced invasiveness of bovine-derived neonatal sequence type 17 group B streptococcus is independent of capsular serotype.
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.
Jones
Nicola
N
Infectious Disease and Microbiology, John Radcliffe Hospital, Oxford, United Kingdom. nicola.jones@ndcls.ox.ac.uk
Oliver
Karen A
KA
Barry
Joanne
J
Harding
Rosalind M
RM
Bisharat
Naiel
N
Spratt
Brian G
BG
Peto
Tim
T
Crook
Derrick W
DW
D000328:Adult; D000368:Aged; D000818:Animals; D016667:Bacterial Capsules / Q000145:classification*; D002353:Carrier State / Q000382:microbiology*; D002417:Cattle / Q000382:microbiology*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D012703:Serotyping; D013290:Streptococcal Infections / Q000453:epidemiology*; D013292:Streptococcus agalactiae / Q000145:classification* / Q000302:isolation & purification*; D014621:Vagina / Q000382:microbiology