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Difficulty: MediumMonitoring and Treatment Evaluation

A 65-year-old man is hospitalized for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia secondary to an infected central venous catheter. The catheter was removed, and he was started on intravenous vancomycin 4 days ago. His clinical status has significantly improved, with resolution of fever and two consecutive sets of negative blood cultures. Today, routine laboratory studies show a serum creatinine level of 2.1 mg/dL, representing a significant increase from his baseline of 1.0 mg/dL on admission. His urine output over the past 24 hours has been 600 mL. A serum vancomycin trough level obtained 30 minutes before the next scheduled dose is 29 mcg/mL (therapeutic target for severe infections: 15-20 mcg/mL). Which of the following is the most appropriate next step in the management of this patient's pharmacotherapy?

  1. Withhold the scheduled vancomycin dose, check daily serum trough levels, and resume therapy at an adjusted dose once the level reaches the therapeutic target.Answer
  2. B
    Administer the scheduled vancomycin dose at half the original amount to prevent a drop in antimicrobial coverage.
  3. C
    Continue the current vancomycin regimen and administer an intravenous normal saline bolus to improve renal perfusion.
  4. D
    Discontinue vancomycin and immediately switch to intravenous daptomycin for the remainder of the treatment course.
  5. E
    Continue vancomycin at a reduced dose and add intravenous piperacillin-tazobactam for synergistic activity.

Answer

The correct action is to withhold the scheduled vancomycin dose, monitor daily serum trough levels, and resume therapy at an adjusted dose once the level reaches the therapeutic target.
The patient has developed acute kidney injury (AKI) secondary to vancomycin toxicity, evidenced by a rise in serum creatinine and a supratherapeutic trough level of 29 mcg/mL. The most appropriate management is to withhold further doses of vancomycin, monitor serum levels daily, and resume therapy at a lower dose or extended interval once the level falls back into the therapeutic range (15-20 mcg/mL). This prevents further nephrotoxicity while ensuring the patient eventually receives adequate antimicrobial coverage for their MRSA bacteremia.

Step-by-Step Solution

1
Identify the primary clinical problem.
The patient has developed acute kidney injury (AKI) in the setting of a supratherapeutic vancomycin trough level (29 mcg/mL).
Recognizing the correlation between the rising creatinine and the high drug level is essential to identify the etiology of the renal failure.
2
Determine the optimal immediate intervention.
The most pressing need is to prevent further nephrotoxicity by stopping the offending agent.
Vancomycin causes dose-dependent intrinsic renal damage; adding more drug, even at a reduced dose, will worsen the AKI.
3
Formulate an ongoing monitoring and treatment plan.
Serial vancomycin levels must be drawn until the trough falls into the target range (15-20 mcg/mL), at which point therapy can be safely resumed at a lower dose or extended interval.
The patient still requires treatment for MRSA bacteremia, and vancomycin remains an effective first-line option once the toxicity is managed.

Key Concept

Management of vancomycin-induced nephrotoxicity requires holding the medication, monitoring serial trough levels, and adjusting the dosing regimen once the drug level falls back into the therapeutic range.
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Topics

Monitoring and Treatment Evaluation

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