What is the recommended once-daily intravenous antibiotic for outpatient treatment of a patient with an E. coli infected pressure wound, sulfa allergy, and normal renal function?

Ertapenem is the Recommended Once-Daily IV Antibiotic for this E. coli Infected Pressure Wound

For this 44-year-old paraplegic patient with an E. coli infected pressure wound, ertapenem 1g IV once daily is the most appropriate antibiotic choice given the sensitivity results, once-daily dosing requirement, and patient's sulfa allergy. 1

Rationale for Antibiotic Selection

Patient-Specific Considerations:

• 44-year-old paraplegic with large pressure wound
• E. coli infection (confirmed by culture)
• Sensitivity to ertapenem, gentamicin, imipenem, and meropenem
• Sulfa allergy (rules out trimethoprim-sulfamethoxazole)
• Normal renal function (creatinine 36, GFR 127)
• Outpatient treatment required with once-daily administration

Antibiotic Options Analysis:

1. Ertapenem (1g IV once daily):

   • Advantages:
     • FDA-approved for once-daily dosing 1
     • Active against E. coli including ESBL-producing strains 2, 3
     • Excellent tissue penetration
     • No dose adjustment needed with normal renal function 1
   • Clinical evidence: Demonstrated 84-87% efficacy in complicated skin and soft tissue infections 4

2. Gentamicin:

   • Concerns:
     • Requires monitoring of drug levels
     • Nephrotoxicity and ototoxicity risks with prolonged use
     • Often used in combination therapy rather than monotherapy for serious infections 5

3. Imipenem/Meropenem:

   • Limitations:
     • Require multiple daily doses (not suitable for once-daily administration)
     • Should be reserved for more severe infections or when other options aren't available 5

Treatment Plan

Dosing and Administration:

• Ertapenem 1g IV once daily 1
• Can be administered by paramedics at the nursing facility
• Duration: 7-14 days based on clinical response 5

Monitoring:

• Follow CRP trends (currently 236)
• Monitor hemoglobin (currently 82)
• Assess wound healing progress
• Watch for signs of treatment failure (increasing erythema, drainage, fever)

Supporting Evidence

The WHO/ESCMID guidelines recommend carbapenems, including ertapenem, for skin and soft tissue infections, particularly when Enterobacteriaceae are involved 5. Ertapenem is specifically indicated for once-daily treatment of complicated skin and soft tissue infections 1.

Clinical studies demonstrate that ertapenem is highly effective against E. coli with response rates of 82% in complicated skin and soft tissue infections 4. A pooled analysis showed 81% efficacy specifically for skin/skin structure infections caused by Enterobacteriaceae 6.

Important Considerations

Advantages of Ertapenem in This Case:

• Once-daily dosing aligns perfectly with the paramedic visit constraints
• Broad coverage against gram-negative organisms including E. coli
• No renal dose adjustment needed with patient's normal renal function
• Preserves other carbapenems (imipenem, meropenem) for more severe infections

Potential Pitfalls:

• Monitor for development of carbapenem resistance
• Ensure proper wound care alongside antibiotic therapy
• Consider nutritional support to promote healing (note: hemoglobin is low at 82)
• If no improvement after 72 hours, reassess wound and consider surgical debridement

Adjunctive Measures

• Pressure offloading is essential
• Regular wound assessment and debridement as needed
• Nutritional support to address anemia (Hgb 82)
• Consider topical antimicrobial dressings as adjunctive therapy

Ertapenem's once-daily dosing, excellent activity against E. coli, and compatibility with the patient's clinical situation make it the optimal choice for outpatient treatment of this infected pressure wound.