What is the recommended treatment for a patient with suspected peritonitis?

Treatment of Suspected Peritonitis

Patients with suspected peritonitis require immediate broad-spectrum antibiotics within 1 hour (especially if septic shock is present) and emergency surgical intervention to drain infected foci and control peritoneal contamination. 1

Immediate Resuscitation and Initial Management

• Initiate aggressive fluid resuscitation immediately to enhance visceral perfusion and address volume depletion in all patients with peritonitis 1
• Administer broad-spectrum antibiotics as soon as possible, ideally within 1 hour for patients with septic shock, before any surgical intervention 1
• Empiric antibiotic therapy must target Gram-negative, Gram-positive, and anaerobic bacteria given the polymicrobial nature of peritonitis 1

Distinguishing Secondary from Spontaneous Bacterial Peritonitis

This distinction is critical because unnecessary laparotomy in cirrhotic patients increases mortality, while delayed surgery in secondary peritonitis is fatal 2:

Suspect secondary bacterial peritonitis when:

• PMN count >1,000/mm³ (rather than the typical >250/mm³ for spontaneous bacterial peritonitis) 2
• Multiple organisms seen on Gram stain or culture 2
• Ascitic total protein ≥1 g/dL 2
• Ascitic LDH above normal serum upper limit 2
• Ascitic glucose ≤50 mg/dL 2
• PMN count fails to drop after 48 hours of antibiotic treatment 2
• Elevated ascitic CEA (>5 ng/mL) or alkaline phosphatase (>240 U/L) suggesting intestinal perforation 2

If secondary bacterial peritonitis is suspected, perform abdominal CT scanning immediately and proceed to early surgical intervention 2

Empiric Antibiotic Selection

For Community-Acquired Peritonitis (Non-Critically Ill):

• Piperacillin/tazobactam is the recommended first-line agent for non-critically ill, immunocompetent patients with adequate source control 1
• Alternative regimens include cefotaxime 2 g every 6-8 hours IV or ceftriaxone 1 g every 12-24 hours IV 2
• Amoxicillin-clavulanic acid shows similar resolution rates to cefotaxime but has concerns for drug-induced liver injury 2

For High-Risk or Critically Ill Patients:

• For patients at high risk of ESBL-producing Enterobacterales, use ertapenem or eravacycline 1
• For septic shock, use meropenem, doripenem, imipenem/cilastatin, or eravacycline 1
• Carbapenems should be reserved for nosocomial cases, healthcare-associated infections, or recent broad-spectrum antibiotic exposure 3

Coverage Considerations:

• Avoid aminoglycosides as empirical therapy due to nephrotoxicity 2
• Antifungal therapy (fluconazole) is recommended for hospital-acquired infections and critically ill or severely immunocompromised patients 1

Surgical Management

Emergency surgical intervention should be performed as soon as possible in patients with diffuse peritonitis, even if physiologic stabilization measures need to continue during the procedure 1:

• The primary surgical goals are to drain infected foci, control ongoing peritoneal contamination, and restore anatomic and physiological function 1
• For perforated diverticulitis with diffuse peritonitis, Hartmann's procedure is recommended in critically ill patients 1
• Inadequate source control is the most common reason for treatment failure 3
• Delay in surgical control significantly increases mortality 3

Duration of Antibiotic Therapy

For patients with adequate source control, use a short course of 3-5 days of antibiotic therapy 1:

• For immunocompromised or critically ill patients with adequate source control, extend antibiotic therapy up to 7 days 1, 3
• Duration can be shortened if PMN count in peritoneal fluid decreases to <250/mm³ before day 5-7 3
• Perform follow-up paracentesis at 48 hours to evaluate response; a decrease in PMN count <25% of baseline indicates treatment failure 3

Monitoring and Re-evaluation

• Serial assessment of inflammatory markers (CRP, procalcitonin, WBC) guides duration decisions 3
• Clinical improvement should be evident within 48-72 hours of appropriate therapy and source control 3
• Lack of improvement warrants re-evaluation for resistant organisms or inadequate source control 3
• Patients with ongoing signs of infection beyond 7 days require diagnostic re-evaluation and multidisciplinary assessment 3

Special Considerations for Spontaneous Bacterial Peritonitis in Cirrhosis

If spontaneous bacterial peritonitis is suspected and PMN count is >250/mm³, start empirical antibiotics immediately regardless of culture results 2:

• Even with PMN <250/mm³, if symptoms or signs of infection are present (temperature >37.8°C, abdominal pain or tenderness), administer empirical antibiotics until culture results are available 2
• Standard treatment duration is 5-10 days, adjusted according to symptoms and antimicrobial susceptibility results 2
• Oral ofloxacin has shown similar results to IV cefotaxime in uncomplicated SBP without renal failure, hepatic encephalopathy, GI bleeding, ileus, or shock 2

Common Pitfalls to Avoid

• Do not perform unnecessary laparotomy in cirrhotic patients with spontaneous bacterial peritonitis, as this increases mortality 2
• Do not use prolonged courses of broad-spectrum antibiotics empirically in patients with persistent inflammation without searching for new infection sources, as this promotes multidrug-resistant organisms 4
• Previous broad-spectrum antibiotic exposure is the most important risk factor for multidrug-resistant organisms in postoperative peritonitis 3
• On-demand re-laparotomy is recommended for severe peritonitis rather than planned re-laparotomy, as it streamlines resources and reduces costs 1