Change in prevalence of group B Streptococcus maternal colonisation in Hong Kong.

Objectives: To re-examine the prevalence of group B Streptococcus colonisation in our antenatal population, and identify demographic factors associated with carriage.

Design: Prospective observational study.

Setting: A tertiary obstetrics unit in Hong Kong.

Participants: A total of 1002 pregnant women were recruited at the booking clinic in a tertiary obstetrics unit in Hong Kong. High and low vaginal swabs and rectal swabs were taken for group B Streptococcus culture. Demographic data and delivery outcomes of the recruits were analysed.

Results: The prevalence of group B Streptococcus colonisation in our antenatal population was 10.4%. The majority of carriers were identified by low vaginal swabs (78%), while high vaginal swabs and rectal swabs only identified 31% and 30% of the carriers, respectively. Professional women yielded a higher carrier rate than housewives (21% vs 10%, P=0.03). There was no increase in preterm delivery rate in group B Streptococcus carriers.

Conclusions: We noted a dramatic increase in the prevalence of group B Streptococcus colonisation in the Hong Kong pregnant population at their booking visit. Professional women had a higher colonisation rate compared to other groups.