Which of the following can be prevented by using a solution of 3% boric acid and alcohol?

Question

BlackTom AI · Accepted Answer

3% boric acid in alcohol is a topical antiseptic/acidifying solution used as an ear drop to prevent external ear infections (otitis externa), especially after swimming.

1) Relevant knowledge points and concepts
- Otitis externa (swimmer’s ear) is an infection/inflammation of the external auditory canal often promoted by retained water, alkaline pH, and microbial overgrowth (Pseudomonas, Staphylococcus, fungi).
- An acidifying, drying topical agent reduces microbial proliferation in the external canal. Boric acid provides mild acidity and antiseptic action; alcohol provides drying and additional antimicrobial effect.
- This preparation is intended for the external ear canal only and is contraindicated if the tympanic membrane is perforated.

2) Step-by-step reasoning
- Problem to prevent: an infection of the external auditory canal after moisture exposure.
- Intervention: instillation of a 3% boric acid + alcohol solution into the external auditory canal after swimming or water exposure.
- Mechanism: lowering pH (boric acid) and drying the canal (alcohol) create an environment unfavorable to bacteria and fungi, reducing colonization and therefore preventing otitis externa.
- Outcome: reduced incidence of swimmer’s ear when used prophylactically with an intact tympanic membrane.

3) Calculations
- Not applicable (no numeric computation required).

4) Why the correct answer is correct
- A 3% boric acid–alcohol solution is a classical prophylactic ear drop for otitis externa because it directly alters the canal environment to inhibit microbial growth and remove moisture that predisposes to infection.

5) Why the other choices are incorrect
- Otitis media: infection of the middle ear (behind an intact tympanic membrane) — not prevented by topical external ear drops; requires systemic/localized middle-ear treatments.
- Epistaxis: nasal bleeding — unrelated to ear canal topical antiseptics.
- Hyphema: blood in the anterior chamber of the eye — unrelated and not prevented by ear drops.

Conclusion: The correct answer is a. Otitis externa, which matches the provided answer.

Which of the following can be prevented by using a solution of 3% boric acid and alcohol?单项选择题

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