What is the recommended dose of ertapenem (a carbapenem antibiotic) for an adult patient with normal renal function and a Serratia marcescens infection?

Ertapenem Dosing for Serratia marcescens Infection

For an adult patient with normal renal function and Serratia marcescens infection, administer ertapenem 1 gram intravenously once daily, infused over 30 minutes. 1

Standard Dosing Regimen

Adults (≥13 years) with normal renal function:

• Dose: 1 gram IV once daily 1
• Infusion time: 30 minutes 1
• Duration: 10-14 days depending on infection site and clinical response 1, 2

Pediatric patients (3 months to 12 years):

• Dose: 15 mg/kg IV twice daily (maximum 1 g/day) 1

Evidence Supporting Ertapenem for Serratia marcescens

Ertapenem demonstrates excellent activity against Enterobacteriaceae, including Serratia species. 3 A multicenter randomized study showed ertapenem 1 g once daily was equivalent to ceftriaxone for community-acquired pneumonia caused by Enterobacteriaceae and as efficacious as cefepime for pneumonia with Enterobacteriaceae infection. 3

Clinical case evidence: A 73-year-old immunocompromised patient with multiple leg ulcers and abscesses caused by S. marcescens was successfully treated with ertapenem 1 g/day IV for 10 days, followed by oral ciprofloxacin, resulting in complete resolution. 2 This demonstrates ertapenem's clinical efficacy for serious S. marcescens infections. 2

Dosing Modifications

Renal impairment:

• CrCl >30 mL/min/1.73 m²: No adjustment needed 1
• CrCl ≤30 mL/min/1.73 m²: Reduce to 500 mg daily 1
• End-stage renal disease (CrCl ≤10 mL/min/1.73 m²): 500 mg daily 1

Hemodialysis patients:

• Give 500 mg daily 1
• If ertapenem administered within 6 hours before hemodialysis, give supplementary 150 mg dose after dialysis session 1
• If given ≥6 hours before hemodialysis, no supplementary dose needed 1

Hepatic impairment:

• No dose adjustment recommendations available 1

No adjustments needed for:

• Gender, age, or weight in adults 4

Important Clinical Considerations

Carbapenem resistance: Be aware that KPC-2-producing S. marcescens strains have emerged, with MICs for ertapenem ranging from 2 to >128 μg/mL in resistant isolates. 5 Always obtain susceptibility testing before or during treatment. 1

Ertapenem limitations: Unlike other carbapenems, ertapenem lacks activity against Pseudomonas aeruginosa, Acinetobacter species, and enterococci. 6 If polymicrobial infection is suspected with these organisms, choose meropenem or imipenem instead. 6

Pharmacokinetic concerns in special populations: Standard 1 g/day dosing may not provide adequate free drug concentrations in critically ill patients or those with BMI >20 kg/m². 6 Consider shortening dosing intervals or continuous infusion in these populations. 6

Administration Guidelines

• Do NOT mix or co-infuse with other medications 1
• Do NOT use diluents containing dextrose 1
• Reconstitute 1 g vial with 10 mL of Water for Injection, 0.9% Sodium Chloride, or Bacteriostatic Water 1
• Dilute in 50 mL of 0.9% Sodium Chloride 1
• Complete infusion within 6 hours of reconstitution 1

Treatment Duration by Infection Type

• Complicated intra-abdominal infections: 5-14 days 1
• Complicated skin/soft tissue infections: 7-14 days 1
• Community-acquired pneumonia: 10-14 days 1
• Complicated UTI/pyelonephritis: 10-14 days 1
• Acute pelvic infections: 3-10 days 1