Bacteriology: group B streptococcus: practice question

A Microbiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Microbiology · Bacteriology: group B streptococcus

Sample item

A woman at 36 weeks of gestation has a rectovaginal swab culture positive for Streptococcus agalactiae. She goes into labour at term with no allergies. What is the best way to prevent early-onset neonatal sepsis?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Intravenous penicillin G given during labour

Group B streptococcus colonises the maternal genital tract and is acquired by the neonate during delivery. Intrapartum intravenous penicillin, with adequate dose time before delivery, is the standard prophylaxis, with cefazolin or other alternatives for allergy. Antenatal oral treatment does not eradicate colonisation, and caesarean section is not routinely indicated.

Option by option

  • A. Elective caesarean section for all colonised women

    Colonisation alone is not an indication for caesarean section.

  • B. Oral erythromycin to the neonate after birth only

    Postnatal erythromycin alone does not provide reliable prevention.

  • C. Intravenous penicillin G given during labour (correct)

    Correct. Intrapartum penicillin reduces vertical transmission and early-onset disease.

  • D. Oral amoxicillin started immediately after the report

    Oral treatment before labour does not eliminate colonisation, which recurs.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is C, Intravenous penicillin G given during labour. Group B streptococcus colonises the maternal genital tract and is acquired by the neonate during delivery.

Why is "Elective caesarean section for all colonised women" not the answer?

Colonisation alone is not an indication for caesarean section.

Why is "Oral erythromycin to the neonate after birth only" not the answer?

Postnatal erythromycin alone does not provide reliable prevention.

Why is "Oral amoxicillin started immediately after the report" not the answer?

Oral treatment before labour does not eliminate colonisation, which recurs.

What concept does this question test?

It tests Bacteriology: group B streptococcus in Microbiology. Intrapartum intravenous penicillin, with adequate dose time before delivery, is the standard prophylaxis, with cefazolin or other alternatives for allergy. Antenatal oral treatment does not eradicate colonisation, and caesarean section is not routinely indicated.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Bacteriology: group B streptococcus?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.