What is the appropriate use and dosage of Ceftazidime (Ceftazidime)/avibactam for a patient with a complicated urinary tract infection, intra-abdominal infection, or pneumonia caused by suspected or confirmed Gram-negative bacteria, considering potential renal impairment and allergy to beta-lactam (beta-lactam) antibiotics?

Ceftazidime/Avibactam: Appropriate Use and Dosing

Ceftazidime/avibactam is indicated for complicated urinary tract infections, complicated intra-abdominal infections (combined with metronidazole), and hospital-acquired/ventilator-associated pneumonia caused by susceptible Gram-negative bacteria, with dosing of 2.5 grams IV every 8 hours over 2 hours in adults with normal renal function. 1

FDA-Approved Indications

Ceftazidime/avibactam is approved for three specific infection types in adults and pediatric patients (at least 31 weeks gestational age) 1:

• Complicated intra-abdominal infections (cIAI): Must be used in combination with metronidazole 500 mg IV every 8 hours 1. Active against E. coli, K. pneumoniae, P. mirabilis, E. cloacae, K. oxytoca, Citrobacter freundii complex, and P. aeruginosa 1.

• Complicated urinary tract infections (cUTI) including pyelonephritis: Active against E. coli, K. pneumoniae, E. cloacae, Citrobacter freundii complex, P. mirabilis, and P. aeruginosa 1.

• Hospital-acquired bacterial pneumonia/ventilator-associated bacterial pneumonia (HABP/VABP): Active against K. pneumoniae, E. cloacae, E. coli, S. marcescens, P. mirabilis, P. aeruginosa, and H. influenzae 1.

Standard Dosing Regimen

Adults (≥18 years with CrCl >50 mL/min)

Standard dose: 2.5 grams (ceftazidime 2 grams + avibactam 0.5 grams) IV every 8 hours, infused over 2 hours 1:

• cIAI: 5-14 days duration (with metronidazole) 1
• cUTI: 7-14 days duration 1
• HABP/VABP: 7-14 days duration 1

Pediatric Patients

Dosing varies by age and weight 1:

• 2 years to <18 years: 62.5 mg/kg (maximum 2.5 grams) IV every 8 hours 1
• 6 months to <2 years: 62.5 mg/kg IV every 8 hours 1
• 3 months to <6 months: 50 mg/kg IV every 8 hours 1
• >28 days to <3 months: 37.5 mg/kg IV every 8 hours 1
• ≤28 days (≥31 weeks gestational age): 25 mg/kg IV every 8 hours 1

Renal Impairment Dosing Adjustments

Monitor creatinine clearance daily in patients with renal impairment and adjust dosing accordingly 1:

• CrCl 31-50 mL/min: 1.25 grams IV every 8 hours 1
• CrCl 16-30 mL/min: 0.94 grams IV every 12 hours 1
• CrCl 6-15 mL/min: 0.94 grams IV every 24 hours 1
• CrCl ≤5 mL/min on hemodialysis: 0.94 grams IV every 48 hours (after hemodialysis on dialysis days) 1

For pediatric patients ≥2 years with eGFR ≤50 mL/min/1.73 m², dosage adjustments are required 1. There is insufficient data for dosing in pediatric patients <2 years with renal impairment 1.

Role in Multidrug-Resistant Infections

Carbapenem-Resistant Enterobacterales (CRE)

Ceftazidime/avibactam is a first-line agent for infections caused by KPC-producing and OXA-48-producing CRE 2, 3, 4:

• For severe CRE infections: Ceftazidime/avibactam or meropenem/vaborbactam are preferred if active in vitro 2
• KPC-producing CRE: Strongly recommended as first-line therapy, with superior outcomes compared to polymyxin-based regimens 3, 4
• OXA-48-producing CRE: Should be the first-line treatment option 3
• Metallo-β-lactamase-producing CRE: Ceftazidime/avibactam combined with aztreonam is preferred over other therapies 4

Treatment duration for CRE infections 5:

• Bloodstream infections: 7-14 days 5
• Complicated UTI: 5-7 days 5
• Complicated intra-abdominal infections: 5-7 days (with metronidazole) 5

ESBL-Producing Enterobacteriaceae

Ceftazidime/avibactam demonstrates strong activity against ESBL-producing organisms and should be reserved for multidrug-resistant pathogens to preserve carbapenems 6, 7, 6. These agents are valuable for treating infections caused by Gram-negative MDROs, particularly when carbapenem-sparing strategies are desired 6.

Beta-Lactam Allergy Considerations

Ceftazidime/avibactam is contraindicated in patients with known serious hypersensitivity to ceftazidime, avibactam, or other cephalosporins 1. Cross-reactivity between cephalosporins and penicillins occurs in approximately 1-10% of patients with penicillin allergy, with higher risk in those with immediate-type reactions 1.

Alternative agents for beta-lactam allergic patients 5, 6:

• Fluoroquinolones (ciprofloxacin with metronidazole for cIAI) - reserved for mild infections without risk factors for resistant pathogens 6
• Aminoglycosides (gentamicin, amikacin) - particularly for UTI caused by CRE 5
• Polymyxin-based combinations (colistin plus tigecycline or meropenem) for severe CRE infections 5

Clinical Efficacy Data

In the REPRISE trial, ceftazidime/avibactam demonstrated 91% clinical cure rates in ceftazidime-resistant Enterobacteriaceae and P. aeruginosa infections, comparable to carbapenem-based best available therapy 8. Real-world data shows 30-day mortality rates of 18.3% with ceftazidime/avibactam versus 40.8% with other active agents for KPC-producing K. pneumoniae bloodstream infections 3.

Important Caveats

• Anaerobic coverage: Ceftazidime/avibactam has limited activity against Bacteroides spp., requiring metronidazole co-administration for intra-abdominal infections 6, 1
• Resistance emergence: KPC variants (D179Y mutations) conferring ceftazidime/avibactam resistance have been reported, particularly with prior exposure 3, 5
• Not active against: Metallo-β-lactamases (unless combined with aztreonam), Acinetobacter spp., Burkholderia spp., or most anaerobic Gram-negative rods 9
• Combination therapy: Not recommended for CRE infections susceptible to ceftazidime/avibactam monotherapy 2
• Antibiotic stewardship: Should be reserved for extensively resistant bacteria and avoided for routine ESBL infections when other options exist 2