What is the treatment for peritonitis?

Treatment of Peritonitis

For community-acquired peritonitis, initiate immediate empirical therapy with a third-generation cephalosporin (cefotaxime 2g IV every 6-8 hours or ceftriaxone 1-2g IV every 12-24 hours) combined with emergency surgical source control, while for hospital-acquired or nosocomial peritonitis, use broad-spectrum coverage with meropenem plus daptomycin due to high rates of multidrug-resistant organisms. 1, 2

Immediate Resuscitation and Initial Management

• Begin aggressive fluid resuscitation immediately to address volume depletion and enhance visceral perfusion before surgical intervention 3, 4
• Administer empirical antibiotics within 1 hour for patients presenting with septic shock 3, 4
• Do not delay emergency surgery while attempting complete physiologic stabilization—resuscitative measures should continue concurrently with surgical intervention 4

Empirical Antibiotic Selection by Clinical Setting

Community-Acquired Peritonitis (Standard Risk)

• First-line therapy: Third-generation cephalosporin 1
  • Cefotaxime 2g IV every 6-8 hours, OR 1
  • Ceftriaxone 1-2g IV every 12-24 hours 1, 3
• Alternative regimens for non-critically ill patients: 3, 5
  • Piperacillin-tazobactam 3
  • Meropenem 1g IV every 8 hours for complicated intra-abdominal infections 5
  • Amoxicillin-clavulanate (though less preferred) 1

Critical caveat: The major pathogens are Escherichia coli, Klebsiella pneumoniae, Streptococcus species, and anaerobes (especially Bacteroides fragilis), requiring coverage of both aerobic and anaerobic organisms 1

Hospital-Acquired or Nosocomial Peritonitis (High-Risk Setting)

• First-line therapy: Meropenem 1g IV every 8 hours PLUS daptomycin 6 mg/kg/day 2
• This combination is significantly more effective than ceftazidime alone (86.7% vs 25% resolution rate, P<0.001) 2
• Alternative for septic shock: meropenem, doripenem, or imipenem-cilastatin 3

Key distinction: Hospital-acquired infections have dramatically higher rates of multidrug-resistant organisms (MDRO), with MDRO prevalence increasing from 41% at initial surgery to 76% by the third reoperation 1

Patients with Risk Factors for Extended-Spectrum Beta-Lactamase (ESBL) Producers

• Risk factors include: recent antibiotic exposure (particularly beta-lactams or fluoroquinolones within 90 days), known ESBL colonization, or healthcare-associated infection 1
• Recommended therapy: Ertapenem or eravacycline 3
• Avoid quinolones in these patients due to resistance rates exceeding 30% in some regions 1

Surgical Source Control

Emergency surgical intervention is mandatory and should not be delayed 4

Primary Surgical Goals

• Drain infected foci 4
• Control ongoing peritoneal contamination 4
• Restore anatomic and physiological function 4

Specific Surgical Approaches

• Perforated diverticulitis with diffuse peritonitis: Hartmann's procedure for critically ill patients 3, 4
• Perforated peptic ulcer or small bowel perforation: Simple closure with or without omental patch for small perforations; resection with primary anastomosis when appropriate 4
• Complicated appendicitis: Appendectomy with peritoneal lavage 6, 5

Intraoperative Specimen Collection

• Collect peritoneal fluid, pus, or tissue (1-2 mL minimum) in sterile, airless containers before antibiotic administration 1
• Send for Gram stain, aerobic and anaerobic culture, and antimicrobial susceptibility testing 1
• Do not use peritoneal swabs or fluid from drain tubes—these are inadequate specimens 1

Adjunctive Therapy for Spontaneous Bacterial Peritonitis (SBP)

• Administer IV albumin in addition to antibiotics: 1.5 g/kg at day 1 and 1.0 g/kg at day 3 1
• Patients with acute kidney injury and/or jaundice at diagnosis benefit most from albumin therapy 1
• Temporarily hold non-selective beta-blockers in patients who develop hypotension (MAP <65 mmHg) or acute kidney injury 1

Duration of Antibiotic Therapy

Standard Duration with Adequate Source Control

• 3-5 days for non-critically ill, immunocompetent patients with adequate source control 3, 6
• Up to 7 days for critically ill or immunocompromised patients 3, 6
• For SBP specifically: 5-7 days total 1

Monitoring Response to Therapy

• Perform repeat paracentesis or diagnostic tap at 48 hours after initiating antibiotics 1
• Treatment failure is defined as: decrease in polymorphonuclear (PMN) count <25% from baseline 1
• If treatment fails, broaden antibiotic spectrum and investigate for secondary peritonitis with abdominal imaging 1

Important principle: The STOP-IT trial demonstrated that fixed-duration therapy of approximately 4 days produces outcomes similar to longer courses (approximately 8 days) when adequate source control is achieved 6

De-escalation Strategy

• Tailor antibiotics based on culture results and antimicrobial susceptibility testing once available 1, 6
• Use a de-escalation approach to narrow spectrum and avoid promoting antimicrobial resistance 6
• Discontinue antibiotics when clinical response is achieved: fever resolution, decreasing white blood cell count, normalizing C-reactive protein 6

Antifungal Therapy Considerations

• Do not routinely administer empirical antifungal therapy 6
• Reserve antifungal therapy (fluconazole or amphotericin B) for: 1, 3, 6
  • Hospital-acquired infections
  • Critically ill patients
  • Severely immunocompromised patients
  • Positive Gram stain or culture showing yeast 1

Special Population: Pediatric Patients

• For children ≥3 months with perforated appendicitis: 1, 6
  • Meropenem 10-40 mg/kg every 8 hours (maximum 2g every 8 hours), OR 5
  • Piperacillin-tazobactam, OR 1
  • Cefotaxime/ceftriaxone/ceftazidime/cefepime PLUS metronidazole 1
• 24 hours of postoperative antibiotics is safe and effective for complicated appendicitis in children, resulting in shorter hospital stays without increased complications 6
• Maximum duration: 3-5 days with adequate source control 6

Common Pitfalls to Avoid

• Delaying surgical intervention while attempting complete physiologic stabilization increases mortality—surgery and resuscitation must occur simultaneously 4
• Prolonging antibiotics beyond 5 days when adequate source control is achieved increases antimicrobial resistance and adverse effects without improving outcomes 6
• Using quinolones empirically in areas with high resistance rates (>30% in some regions) or in patients with prior quinolone exposure 1
• Failing to collect peritoneal specimens before starting antibiotics limits ability to appropriately de-escalate therapy 6
• Routine use of antifungal agents without appropriate indications provides no mortality benefit in immunocompetent patients 6
• Assuming antibiotics compensate for inadequate source control—surgical intervention remains essential regardless of antibiotic choice 6
• Using ceftazidime alone for nosocomial peritonitis—this has only 25% efficacy compared to 86.7% with meropenem plus daptomycin 2

Postoperative Management and Reoperation

• On-demand relaparotomy (based on clinical deterioration) is preferred over scheduled relaparotomy, as it streamlines resources and reduces costs 3
• Collect intraperitoneal specimens at every reoperation due to progressive shift toward MDRO with each subsequent surgery 1
• Open abdomen may be necessary for physiologically deranged patients with ongoing sepsis, facilitating subsequent exploration and preventing abdominal compartment syndrome 3