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. Yellow-tinged sputum is not uncommon in patients with pneumonia and while it should be monitored, it is not typically a sign of an adverse reaction to linezolid. B. Nausea and headache may occur with many medications and are not specific to linezolid; these symptoms should be reported, but they are not the most critical. C. Watery diarrhea could indicate a potentially serious condition known as Clostridium difficile- associated diarrhea, which is an important complication to report when a patient is on antibiotics like linezolid. D. Increased fatigue can be associated with the client's underlying condition of pneumonia and while it should be assessed, it is not the most critical finding to report in relation to linezolid therapy.