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Zorluk: OrtaPharmacologic Interventions

A 68-year-old man is evaluated in the intensive care unit for decreased urine output. He was admitted 8 days ago for a severe exacerbation of chronic obstructive pulmonary disease requiring endotracheal intubation and mechanical ventilation. On hospital day 5, he developed a fever, increased oxygen requirements, and new infiltrates on chest radiography. Endotracheal aspirate cultures subsequently grew Methicillin-resistant Staphylococcus aureus (MRSA), and he was started on intravenous vancomycin. Today, his urine output over the past 24 hours has been 350 mL. Temperature is 37.8°C (100.0°F), blood pressure is 110/70 mm Hg, and pulse is 92/min. Laboratory studies show a serum blood urea nitrogen of 48 mg/dL and a serum creatinine of 3.2 mg/dL (baseline was 1.1 mg/dL upon admission). The serum vancomycin trough level is 34 mcg/mL (therapeutic range: 15-20 mcg/mL). The physician decides to discontinue vancomycin due to acute kidney injury. Which of the following is the most appropriate alternative pharmacologic intervention to treat this patient's pulmonary infection?

  1. Intravenous linezolidCevap
  2. B
    Intravenous daptomycin
  3. C
    Intravenous meropenem
  4. D
    Intravenous tigecycline
  5. E
    Decrease vancomycin dose and administer intravenous fluids

Cevap

The most appropriate pharmacologic intervention is to initiate intravenous linezolid.
The correct answer is to switch therapy to intravenous linezolid. This patient developed severe, oliguric acute kidney injury secondary to vancomycin, as evidenced by a near-tripling of his serum creatinine, decreased urine output, and a supratherapeutic vancomycin trough level. The appropriate management is the immediate cessation of the nephrotoxin. Because he still requires treatment for MRSA ventilator-associated pneumonia, an alternative agent must be selected. Linezolid is an oxazolidinone antibiotic that possesses excellent activity against MRSA, achieves high concentrations in the epithelial lining fluid of the lungs, and does not carry a risk of nephrotoxicity. Furthermore, it does not require dose adjustments in the setting of renal failure.

Adım Adım Çözüm

1
Identify the patient's current active problem.
The patient has ventilator-associated pneumonia caused by MRSA, complicated by severe oliguric acute kidney injury (AKI) secondary to vancomycin toxicity.
Recognizing the cause of the AKI dictates that the offending nephrotoxic agent must be completely stopped.
2
Determine the necessary antimicrobial coverage.
The patient requires an antibiotic that is highly active against MRSA and achieves adequate therapeutic concentrations in the pulmonary parenchyma.
The underlying infection is a severe, lower respiratory tract infection (pneumonia).
3
Evaluate the pharmacologic properties of available MRSA-active agents.
Linezolid provides excellent lung penetration and is not nephrotoxic. Daptomycin covers MRSA but is inactivated in the lungs. Meropenem lacks MRSA coverage.
Matching the drug's pharmacokinetic properties to the site of infection and the patient's organ function is essential for safe and effective therapy.

Anahtar Kavram

In patients with MRSA pneumonia who develop severe acute kidney injury from vancomycin, linezolid is the preferred alternative agent because it achieves high lung concentrations and does not cause nephrotoxicity.
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