In neutropenic patients, which organism is most commonly associated with bloodstream infection?

• A. Escherichia coli
• B. Pseudomonas aeruginosa
• C. Candida albicans
• D. Staphylococcus aureus

Answer: (C)

In neutropenia, the body's neutrophil-driven defenses against fungi are severely weakened, allowing opportunistic organisms like Candida to invade the bloodstream. Candida albicans is a common gut and mucosal colonizer that can translocate into the blood when neutrophils are scarce, especially in patients with central venous catheters or after broad-spectrum antibiotics. This makes Candida albicans the organism most commonly associated with fungemia in this setting. While bacteria such as E. coli or Pseudomonas can cause bloodstream infections in neutropenic patients and Staphylococcus aureus can also be involved, the question specifically targets fungal bloodstream infection, for which Candida albicans is the classic culprit.