Ertapenem vs Tigecycline for Complicated Intra-Abdominal Infection
For adults with complicated intra-abdominal infections, ertapenem is the preferred first-line agent over tigecycline, particularly for mild-to-moderate community-acquired infections. 1
Guideline-Based Recommendations
Ertapenem as Preferred Agent
Both the 2010 IDSA/SIS guidelines explicitly list ertapenem as a recommended single-agent therapy for mild-to-moderate community-acquired complicated intra-abdominal infections (A-I evidence). 1 The 2003 IDSA guidelines similarly recommend ertapenem for this indication. 1
Concerns About Tigecycline Use
The IDSA/SIS Expert Panel specifically expresses concern about using tigecycline for mild-to-moderate complicated intra-abdominal infections due to its excessively broad spectrum. 1 The guidelines note that tigecycline's activity against MRSA and a wide variety of gram-positive and gram-negative organisms not commonly seen in appendix-derived infection makes it unnecessarily broad for routine community-acquired infections. 1
The guidelines explicitly warn against using agents appropriate for higher-severity infections in mild-to-moderate cases, as such regimens carry greater risk of toxicity and facilitate acquisition of more-resistant organisms (B-II evidence). 1
Clinical Algorithm for Selection
Use Ertapenem When:
- Community-acquired infection of mild-to-moderate severity 1
- Appendiceal or colonic source requiring anaerobic coverage 1
- Patient has normal renal function 1
- Once-daily dosing is advantageous (1g every 24 hours) 1
Reserve Tigecycline For:
- Healthcare-associated infections with suspected multidrug-resistant organisms 1
- Patients with severe β-lactam allergies where carbapenems are contraindicated 1
- High-severity infections when ertapenem's narrower spectrum is insufficient 1
Evidence Quality and Efficacy
Ertapenem Evidence
Meta-analysis of 6 randomized controlled trials involving 2,002 patients demonstrated ertapenem has equivalent efficacy to piperacillin/tazobactam and ceftriaxone plus metronidazole for complicated intra-abdominal infections (OR: 1.11,95% CI: 0.89-1.39). 2 Individual trials showed cure rates of 79-87% in modified intent-to-treat populations. 3, 4
Tigecycline Evidence
Pooled analysis of 2 phase 3 trials with 1,642 patients showed tigecycline had clinical cure rates of 86.1% versus 86.2% for imipenem-cilastatin in microbiologically evaluable patients. 5 However, tigecycline was associated with significantly higher rates of nausea (24.4% vs 19.0%, P=0.01) and vomiting (19.2% vs 14.3%, P=0.008). 5, 6
Critical Antimicrobial Stewardship Considerations
The Expert Panel specifically warns that broad use of ertapenem may hasten the appearance of carbapenem-resistant Enterobacteriaceae, Pseudomonas, and Acinetobacter species. 1 However, this concern is even greater for tigecycline given its ultra-broad spectrum including MRSA coverage. 1
For high-severity community-acquired infections or healthcare-associated infections, broader-spectrum carbapenems (imipenem-cilastatin, meropenem, doripenem) are preferred over both ertapenem and tigecycline. 1, 7
Dosing and Duration
- Ertapenem: 1g IV every 24 hours 1
- Tigecycline: 100mg initial dose, then 50mg IV every 12 hours 1
- Duration: 4-7 days for both agents when adequate source control is achieved 1
Common Pitfalls to Avoid
Do not use tigecycline as routine first-line therapy for community-acquired appendicitis or diverticulitis—this represents inappropriate antimicrobial stewardship. 1 The unnecessarily broad spectrum promotes resistance without improving outcomes in these common scenarios. 1
Do not assume ertapenem provides adequate Pseudomonas coverage—it does not. 1 For healthcare-associated infections or high-severity cases requiring anti-pseudomonal activity, use meropenem, imipenem-cilastatin, or doripenem instead. 1, 7