Risk factors for group B streptococcal colonization: potential for different transmission systems by capsular type.
OBJECTIVE
Group B Streptococcus (GBS) is a common inhabitant of the bowel and vaginal flora, with known transmission routes including sexual contact and vertical transmission from mother to infant. Food-borne transmission is also possible, as GBS is a known fish and bovine pathogen. We conducted a prospective cohort study in order to identify risk factors for acquisition.


METHODS
We identified risk factors for GBS acquisition among college women (n = 129) and men (n = 128) followed at 3-week intervals for 3 months.


RESULTS
A doubling in sex acts significantly increased incidence of GBS capsular type V by 80% (95% confidence interval [CI]: 1.19, 2.58), and other non-Ia or -Ib types combined by 40% (95% CI: 1.00, 2.06; incidence of capsular type Ia (odds ratio [OR] = 1.2; 95% CI: 0.71, 1.88; p = 0.57) and Ib (OR = 1.5, 95% CI: 0.75, 2.86; p = 0.27) were elevated, although not significantly. After adjustment for sexual activity and sexual history, gender, and eating venue, fish consumption increased risk of acquiring capsular types Ia and Ib combined 7.3 fold (95% CI: 2.34, 19.50), but not of acquiring other capsular types. Beef and milk were not associated with GBS incidence.


CONCLUSIONS
Different GBS capsular types may have different transmission routes.
Foxman
B
B
Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI, USA. bfoxman@umich.edu
Gillespie
B W
BW
Manning
S D
SD
Marrs
C F
CF
D000293:Adolescent; D000328:Adult; D016667:Bacterial Capsules; D004032:Diet; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006235:Hand Disinfection; D006801:Humans; D015994:Incidence; D008297:Male; D008824:Michigan / Q000453:epidemiology; D011135:Polysaccharides, Bacterial / Q000302:isolation & purification; D011446:Prospective Studies; D012307:Risk Factors; D012725:Sexual Behavior; D013290:Streptococcal Infections / Q000453:epidemiology / Q000635:transmission*; D013292:Streptococcus agalactiae / Q000145:classification / Q000302:isolation & purification* / Q000472:pathogenicity; D013334:Students
D011135:Polysaccharides, Bacterial; C068312:capsular polysaccharide, streptoccal group B type V
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