During the admission assessment of an HIV-positive patient whose CD4+ count has recently fallen, the nurse carefully assesses for signs and symptoms related to opportunistic infections. What is the most common life-threatening infection?
Correct Answer: D
Rationale: The correct answer is D: Pneumocystis pneumonia. This is the most common life-threatening infection in HIV-positive patients with low CD4+ counts. Pneumocystis pneumonia is caused by the opportunistic pathogen Pneumocystis jirovecii, which can lead to severe respiratory distress and mortality in immunocompromised individuals. The other choices, A: Salmonella infection, B: Mycobacterium tuberculosis, and C: Clostridium difficile, can also cause infections in HIV-positive patients, but they are not as commonly associated with life-threatening complications in this population compared to Pneumocystis pneumonia. It is crucial for the nurse to prioritize assessment for signs and symptoms of Pneumocystis pneumonia in this patient to promptly intervene and prevent further complications.