Red Flags
- Sepsis or septic shock with intra-abdominal source — sepsis pathway with broad-spectrum IV antibiotic within 1 h, fluids, lactate, blood cultures, urgent source control[1]
- Generalised peritonitis with peritonism on examination — emergency surgery; do not delay for imaging if hemodynamically stable enough[1]
- Fecal peritonitis or anastomotic leak — emergency damage-control surgery; ITU; broader cover[1]
- Failure of source control at 48–72 h with persistent sepsis — repeat imaging and reoperation; consider ESBL or fungal coverage[1]
First-line treatment
Interventions
- Source control as cornerstoneAchieve prompt, effective source control by surgery or percutaneous drainage when indicated. Timing depends on illness and source; postoperative peritonitis requires prompt surgical source control. Selected uncomplicated appendicitis or localized abscess pathways can use antibiotics or drainage, so antibiotics alone are not universally inadequate. [2]
- Resuscitation and supportive careGive prompt intravenous crystalloids for sepsis, titrated to clinical perfusion response with frequent reassessment and avoidance of fluid overload. Vasopressors can augment resuscitation when fluids alone fail. Do not substitute a fixed-volume protocol for the guideline’s individualized clinical endpoints. [2]
- Risk-stratified antibiotic choiceChoose empiric antibiotics by severity, acquisition setting and resistance risk. For non-critically ill community-acquired infection, WSES 2017 lists co-amoxiclav, or ceftriaxone/cefotaxime PLUS metronidazole. Severe and healthcare-associated regimens require the complete setting-specific combinations in Appendices 2–4. Consider empiric Candida treatment particularly in hospital-acquired infection with recent abdominal surgery or anastomotic leak; do not infer blanket antifungal or MRSA coverage from recurrence alone. [2]
- Antibiotic durationAfter adequate source control of complicated intra-abdominal infection, use a short antibiotic course of 3–5 days. Persistent peritonitis or systemic illness beyond 5–7 days warrants investigation for uncontrolled infection or treatment failure. Critically ill patients need individualized reassessment; do not extend antibiotics automatically without checking source control. [2]
First-line drug therapy
| Drug | Class | Adult | Paediatric | Notes |
|---|---|---|---|---|
| Piperacillin-tazobactam | Beta-lactam + beta-lactamase inhibitor | For the indicated adult groups with normal renal function, WSES 2017 lists piperacillin/tazobactam 4.5 g every 6 hours. This source does not establish the stored preferred 4-hour infusion schedule. [2] | Per local protocol | Piperacillin/tazobactam is one listed option for critically ill community-acquired infection and non-critically ill healthcare-associated infection. The appendices assume normal renal function; match complete coverage to resistance and organism risk. [2] |
| Meropenem | Carbapenem | Meropenem 1 g every 8 hours is listed for adults with normal renal function, within the relevant complete combination regimen. The cited appendices do not establish the stored 2 g MIC-based escalation. [2] | 20 mg/kg every 8 h | Meropenem is a listed option for selected critically ill community-acquired patients at ESBL risk and healthcare-associated infection. Follow the complete appendix regimen: non-critically ill healthcare-associated patients at higher MDRO risk receive meropenem PLUS ampicillin; other combinations depend on setting and organism risk. [2] |
| Ceftriaxone + metronidazole | Third-generation cephalosporin + nitroimidazole | For non-critically ill adults with community-acquired infection and normal renal function: ceftriaxone 2 g every 24 hours PLUS metronidazole 500 mg every 6 hours. [2] | Ceftriaxone 50–80 mg/kg/day; metronidazole 7.5 mg/kg every 8 h | Ceftriaxone PLUS metronidazole is an option for non-critically ill community-acquired intra-abdominal infection. The cited appendix does not establish an oral cefuroxime switch regimen. [2] |
| Vancomycin or daptomycin (MRSA cover) | Glycopeptide / lipopeptide | The 2017 appendix lists vancomycin 25–30 mg/kg loading, then 15–20 mg/kg per dose every 8 hours for adults with normal renal function. This is a dated 2017 table regimen, not a substitute for individualized contemporary dosing. It does not specify a trough target; current individualized dosing and monitoring require a current source. [2] | 60 mg/kg/day every 6 h | Appendix 4 includes vancomycin as Gram-positive coverage in critically ill healthcare-associated infection. Its daptomycin/linezolid alternatives are specifically under vancomycin-resistant Enterococcus risk. Select agents according to the complete regimen, cultures and resistance risk. [2] |
| Echinocandin (caspofungin, micafungin) for fungal cover | Echinocandin antifungal | Caspofungin 70 mg IV loading then 50 mg daily; micafungin 100 mg daily | Caspofungin 70 mg/m² loading then 50 mg/m²; micafungin 2 mg/kg | Consider empiric Candida treatment in hospital-acquired intra-abdominal infection, especially recent abdominal surgery or anastomotic leak, and significant candidiasis risk with poor response to antibacterial treatment. An echinocandin is preferred for critically ill patients or previous azole exposure; stable patients without azole-resistance risk may have other options. [2] |
Piperacillin-tazobactam
Beta-lactam + beta-lactamase inhibitor
- Adult
- For the indicated adult groups with normal renal function, WSES 2017 lists piperacillin/tazobactam 4.5 g every 6 hours. This source does not establish the stored preferred 4-hour infusion schedule. [2]
- Paediatric
- Per local protocol
Piperacillin/tazobactam is one listed option for critically ill community-acquired infection and non-critically ill healthcare-associated infection. The appendices assume normal renal function; match complete coverage to resistance and organism risk. [2]
Meropenem
Carbapenem
- Adult
- Meropenem 1 g every 8 hours is listed for adults with normal renal function, within the relevant complete combination regimen. The cited appendices do not establish the stored 2 g MIC-based escalation. [2]
- Paediatric
- 20 mg/kg every 8 h
Meropenem is a listed option for selected critically ill community-acquired patients at ESBL risk and healthcare-associated infection. Follow the complete appendix regimen: non-critically ill healthcare-associated patients at higher MDRO risk receive meropenem PLUS ampicillin; other combinations depend on setting and organism risk. [2]
Ceftriaxone + metronidazole
Third-generation cephalosporin + nitroimidazole
- Adult
- For non-critically ill adults with community-acquired infection and normal renal function: ceftriaxone 2 g every 24 hours PLUS metronidazole 500 mg every 6 hours. [2]
- Paediatric
- Ceftriaxone 50–80 mg/kg/day; metronidazole 7.5 mg/kg every 8 h
Ceftriaxone PLUS metronidazole is an option for non-critically ill community-acquired intra-abdominal infection. The cited appendix does not establish an oral cefuroxime switch regimen. [2]
Vancomycin or daptomycin (MRSA cover)
Glycopeptide / lipopeptide
- Adult
- The 2017 appendix lists vancomycin 25–30 mg/kg loading, then 15–20 mg/kg per dose every 8 hours for adults with normal renal function. This is a dated 2017 table regimen, not a substitute for individualized contemporary dosing. It does not specify a trough target; current individualized dosing and monitoring require a current source. [2]
- Paediatric
- 60 mg/kg/day every 6 h
Appendix 4 includes vancomycin as Gram-positive coverage in critically ill healthcare-associated infection. Its daptomycin/linezolid alternatives are specifically under vancomycin-resistant Enterococcus risk. Select agents according to the complete regimen, cultures and resistance risk. [2]
Echinocandin (caspofungin, micafungin) for fungal cover
Echinocandin antifungal
- Adult
- Caspofungin 70 mg IV loading then 50 mg daily; micafungin 100 mg daily
- Paediatric
- Caspofungin 70 mg/m² loading then 50 mg/m²; micafungin 2 mg/kg
Consider empiric Candida treatment in hospital-acquired intra-abdominal infection, especially recent abdominal surgery or anastomotic leak, and significant candidiasis risk with poor response to antibacterial treatment. An echinocandin is preferred for critically ill patients or previous azole exposure; stable patients without azole-resistance risk may have other options. [2]
Safety-net
- Most intra-abdominal infections need surgical or radiologic drainage in addition to antibiotics — antibiotics alone are insufficient[1]
- Persistent fever, rising inflammatory markers, or hemodynamic instability after 48–72 h on appropriate antibiotic — investigate for inadequate source control or resistant organism[1]
- Take antibiotics for the full prescribed course; review at 4 days for switch to oral and discontinuation in adequately drained collections[1]
Referral criteria
- Suspected complicated intra-abdominal infection or peritonitisEmergency department / general surgery[1]
- Septic shock or organ dysfunctionITU and surgical admission[1]
- Recurrent or refractory disease, anastomotic leak, intra-abdominal abscess on imagingTertiary surgery and interventional radiology[1]
- Resistant organism (ESBL, CRE, MDR Pseudomonas) on cultureInfectious diseases / antimicrobial stewardship[1]
Clinical summary
Diagnosis, source control, and antibiotic management of complicated intra-abdominal infection in adults including community- and hospital-acquired peritonitis.
References
- 1.WSES Guidelines for Management of Intra-Abdominal Infections (2017, with 2024 update); IDSA / SIS Guideline on Complicated Intra-Abdominal Infection (2024)
- 2.The management of intra-abdominal infections from a global perspective: 2017 WSES guidelines for management of intra-abdominal infections. World Journal of Emergency Surgery (2017)