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Group B streptococcus bacteriuria — USMLE Step 3 MCQ

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ModerateOB/GYN (prenatal care, contraception, screening)Group B streptococcus bacteriuriaUSMLE Step 3

A 28-year-old pregnant woman at 18 weeks has urine culture growing group B Streptococcus at 100,000 CFU/mL. She has dysuria. She is treated successfully. She asks whether anything else is needed during delivery. Which of the following is the most appropriate at this time?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: B — Plan intrapartum antibiotic prophylaxis

GBS bacteriuria during pregnancy indicates heavy colonization and requires intrapartum antibiotic prophylaxis regardless of later screening.

Reference: CDC/ACOG group B streptococcus prevention guidance: https://www.cdc.gov/group-b-strep/