The Prevalence of Asymptomatic Bacteriuria in Pregnant Hong Kong Women

Abstract

Objectives: To determine the prevalence, causating agents, and associated factors of asymptomatic bacteriuria in Hong Kong pregnant women.
Methods: This was a 6-month prospective cross-sectional epidemiological study carried out in a Hong Kong public hospital from 2 December 2011 to 2 June 2012. Pregnant women, who were Hong Kong residents, attending their first antenatal visit without symptoms of urinary tract infection and able to give written consents were recruited. A mid-stream urine sample was collected from each recruited subject and sent for microscopy and culture to the Department of Microbiology, Queen Elizabeth Hospital, Hong Kong.

Results: Of a total of 1537 urine samples, 87% were collected in the first trimester. On culture of all the samples, 8.3% (95% confidence interval [CI], 6.9-9.7%) were found to yield borderline growth (104-5 colony-forming unit [CFU]/ml), and 2.0% (95% CI, 1.4-2.9%) yielded significant growth (>105 CFU/ml). For borderline growth, Staphylococcus species constituted the most common isolate (42%), followed by Streptococcus species (24%). While for patients with significant growth, the most common isolates were Escherichia coli (33%), followed by Streptococcus agalactiae (21%). Neither age, parity, gestation, education level, or recent sexual activity were definitively associated with asymptomatic bacteriuria.
Conclusion: Among local pregnant women, asymptomatic bacteriuria is common during the first trimester. For patients with significant growth, the common isolates were Escherichia coli and Streptococcus agalactiae, both of which are associated with potential risks in pregnancy.