Which opportunistic infection is commonly associated with antibiotic use?

• A. Candida albicans
• B. Escherichia coli
• C. Staphylococcus aureus
• D. Aspergillus niger

Answer: (A)

Antibiotics can disrupt the protective bacterial flora that normally keep yeast growth in check. Candida albicans is a common fungus that lives in small numbers in the mouth, gut, and vagina, and when bacterial competitors are reduced by antibiotics, Candida can overgrow and cause candidiasis. This is a classic antibiotic-associated opportunistic infection, which is why Candida albicans is the best choice.

The other organisms listed are not the typical antibiotic-associated opportunistic fungus. E. coli is a bacterium that's part of the gut flora; antibiotics can alter bacterial balance but it’s not the classic yeast overgrowth problem. Staphylococcus aureus is a common bacterial pathogen that can cause infections, but again, it’s not the familiar overgrowth issue seen with antibiotics. Aspergillus niger is a mold that can cause disease mainly in severely immunocompromised individuals, not the common consequence of antibiotic use in otherwise healthy individuals.