In caring for a client who is receiving linezolid IV for nosocomial pneumonia, which assessment finding is most important for the nurse to report to the healthcare provider?

A. Increased fatigue: Fatigue is a common side effect during infections and antibiotic therapy but is not an immediate danger unless associated with other severe symptoms like anemia or sepsis. B. Watery diarrhea: Watery diarrhea may indicate Clostridioides difficile (C. diff) infection, a serious and potentially life-threatening complication of antibiotic therapy, requiring immediate reporting and intervention. C. Yellow-tinged sputum: Yellow sputum can suggest ongoing infection, but since the client is already being treated with linezolid, this alone is not as urgent as signs of a severe new gastrointestinal infection. D. Nausea and headache: These are relatively common and mild side effects of linezolid and do not require immediate intervention unless they worsen significantly or are accompanied by other serious symptoms.