Antimicrobials · Beta-lactam/Beta-lactamase Inhibitor Combinations
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Ceftazidime-avibactam is a third-generation cephalosporin paired with a non-beta-lactam beta-lactamase inhibitor.
The primary clinical indication for ceftazidime-avibactam is the treatment of complicated intra-abdominal infections and complicated urinary tract infections caused by multidrug-resistant Gram-negative organisms.
Avibactam effectively inhibits Class A (ESBL, KPC) and Class C (AmpC) beta-lactamases, but lacks activity against Class B metallo-beta-lactamases.
Ceftazidime-avibactam is a preferred agent for treating infections caused by Klebsiella pneumoniae carbapenemase (KPC)-producing organisms.
The drug is frequently utilized as a carbapenem-sparing strategy or as a salvage therapy for carbapenem-resistant Enterobacterales (CRE).
Dosing of ceftazidime-avibactam requires renal dose adjustment in patients with an estimated glomerular filtration rate (eGFR) less than 50 mL/min.
Common adverse effects of ceftazidime-avibactam include nausea, vomiting, and an increased risk of Clostridioides difficile-associated diarrhea.
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A 68-year-old male is admitted to the ICU with a recurrent urinary tract infection following a recent prolonged hospitalization. Urine culture reveals carbapenem-resistant Klebsiella pneumoniae that is susceptible to ceftazidime-avibactam but resistant to all other tested beta-lactams. The patient has a history of chronic kidney disease with a baseline creatinine of 2.1 mg/dL. He is currently hemodynamically stable but requires targeted antimicrobial therapy. The physician initiates treatment with ceftazidime-avibactam.
Which of the following is the most important consideration when prescribing this medication for this patient?
Renal dose adjustment based on eGFR
Ceftazidime-avibactam is renally cleared, and failure to adjust the dose in patients with renal impairment (eGFR < 50 mL/min) can lead to drug accumulation and potential neurotoxicity.
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Classification
Combination Cephalosporin and non-beta-lactam beta-lactamase inhibitor.
Indications
Used for complicated intra-abdominal infections and complicated urinary tract infections (including pyelonephritis).
Mechanism of Action
Ceftazidime inhibits PBP; Avibactam protects against KPC and ESBL enzymes.
Side Effects
Common: nausea, diarrhea. Clostridioides difficile-associated diarrhea.
Contraindications / Monitoring
Hypersensitivity to cephalosporins. Monitor renal function (CrCl) for dose adjustment.
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Mechanism of Action
Ceftazidime binds to penicillin-binding proteins (PBPs) to inhibit bacterial cell wall synthesis. Avibactam is a non-beta-lactam inhibitor that covalently binds to Class A, C, and some Class D beta-lactamases. This synergy restores activity against resistant organisms, specifically Klebsiella pneumoniae carbapenemase (KPC) and ESBL-producing pathogens.
Unique Properties
Unlike traditional inhibitors like tazobactam, avibactam is effective against carbapenem-resistant Enterobacteriaceae (CRE). It provides a critical rescue option for multidrug-resistant Gram-negative infections where Pseudomonas aeruginosa is suspected.
Indications
Indicated for complicated intra-abdominal infections (in combination with metronidazole) and complicated urinary tract infections including pyelonephritis. It is also utilized for hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia.
Pharmacokinetics
Both components are primarily excreted via the kidneys. Dosage adjustments are mandatory for patients with renal impairment (CrCl ≤ 50 mL/min). It is not significantly metabolized by the liver.
Side Effects & Adverse Events
Common adverse reactions include nausea, vomiting, and diarrhea. Clostridioides difficile-associated diarrhea is a significant risk with broad-spectrum antibiotic use. Anaphylaxis may occur in patients with severe penicillin or cephalosporin allergies.
Contraindications
Known severe hypersensitivity to ceftazidime-avibactam or other cephalosporins. Use caution in patients with a history of anaphylaxis to penicillins due to potential cross-reactivity.
Monitoring
Monitor serum creatinine and calculate CrCl to ensure appropriate dosing. Observe for signs of superinfection or persistent diarrhea suggestive of C. difficile infection.
Clinical Pearls
Think of this drug as the 'big gun' for CRE and ESBL infections. On boards, look for a patient with a complicated UTI or intra-abdominal infection who has failed standard carbapenem therapy or has a known carbapenem-resistant isolate.