Antibiotics can lead to yeast overgrowth by altering what?

• A. Destroying all microbes
• B. Infecting tissues directly
• C. Altering normal flora
• D. Stimulating immune response

Answer: (C)

Antibiotics disrupt the balance of microorganisms that normally live on and in our bodies. By killing many of the resident bacteria, they reduce the diversity and numbers of commensal microbes that normally keep yeast populations in check. This loss of colonization resistance allows yeasts, which are usually present in small amounts, to multiply and overgrow, leading to infections such as oral thrush or vaginal candidiasis.

The other ideas don’t fit as the mechanism. Antibiotics don’t wipe out every microbe, they don’t cause direct infection of tissues, and they don’t primarily work by stimulating an immune response to drive fungal growth. The key concept is that altering normal flora creates an environment where yeast can flourish.