What is the recommended treatment for intraabdominal infections?

Treatment of Intraabdominal Infections

For intraabdominal infections, immediate source control through surgical intervention or drainage combined with appropriate antimicrobial therapy is the cornerstone of treatment, with antibiotic selection based on whether the infection is community-acquired (narrower spectrum) or hospital-acquired (broader spectrum), and duration limited to 4-7 days when adequate source control is achieved. 1

Source Control: The Primary Intervention

Surgical source control must be performed as soon as possible and is the most critical determinant of survival. 1, 2 Ineffective control of the septic source is associated with significantly elevated mortality rates. 1

• Timing is critical: Delayed source control increases mortality risk, necessity for reoperation, and prolongs hospitalization. 2
• Methods vary by infection type: This includes cholecystectomy for acute cholecystitis, ERCP for cholangitis, percutaneous drainage for abscesses, or laparotomy for perforated viscus. 1
• On-demand re-laparotomy is recommended over planned re-laparotomy for severe peritonitis to streamline resources and reduce costs. 1

Antimicrobial Therapy: Community-Acquired Infections

Mild-to-Moderate Severity

For mild-to-moderate community-acquired infections, use single-agent therapy with ticarcillin-clavulanate, ertapenem, moxifloxacin, or tigecycline, OR combination therapy with metronidazole PLUS ceftriaxone, cefotaxime, levofloxacin, or ciprofloxacin. 1

• Avoid ampicillin-sulbactam due to high E. coli resistance rates. 1
• Avoid cefotetan and clindamycin due to increasing Bacteroides fragilis resistance. 1
• Avoid aminoglycosides for routine use due to toxicity when equally effective alternatives exist. 1
• Do NOT cover enterococci empirically in community-acquired infections. 1
• Do NOT cover Candida empirically in community-acquired infections. 1

High Severity or Septic Shock

For critically ill patients or septic shock, initiate meropenem 1g IV every 6 hours by extended infusion, doripenem 500mg IV every 8 hours by extended infusion, or imipenem/cilastatin 500mg IV every 6 hours by extended infusion immediately upon diagnosis. 1, 2

• Alternative: Piperacillin/tazobactam 4g/0.5g IV every 6 hours or 16g/2g by continuous infusion. 1, 3
• For beta-lactam allergies: Use eravacycline 1mg/kg IV every 12 hours or tigecycline 100mg IV loading dose then 50mg IV every 12 hours. 1, 2

Antimicrobial Therapy: Hospital-Acquired Infections

For hospital-acquired infections, empiric therapy must be driven by local microbiologic resistance patterns and should include broader-spectrum agents. 1

• Recommended regimens: Meropenem, imipenem-cilastatin, doripenem, piperacillin-tazobactam, or ceftazidime, often in combination with metronidazole. 1
• Add vancomycin for empiric MRSA coverage in patients known to be colonized, with prior treatment failure, or significant antibiotic exposure. 1
• Add anti-enterococcal coverage (ampicillin, piperacillin-tazobactam, or vancomycin) for postoperative infections, patients with prior cephalosporin exposure, immunocompromised patients, or those with valvular heart disease. 1
• Consider antifungal therapy (echinocandin preferred over fluconazole in critically ill) for patients with recent abdominal surgery, anastomotic leak, or when Candida is isolated. 1

Duration of Antibiotic Therapy

Limit antibiotics to 4 days in immunocompetent, non-critically ill patients with adequate source control. 1, 2

• Extend to 7 days for immunocompromised or critically ill patients based on clinical response and inflammatory markers (WBC, CRP, procalcitonin). 1, 2
• Patients with ongoing infection beyond 7 days warrant diagnostic investigation rather than continued empiric antibiotics. 1
• For uncomplicated infections (uncomplicated appendicitis, uncomplicated cholecystitis) where source control is definitive, postoperative antibiotics are NOT necessary. 1
• For traumatic bowel injuries repaired within 12 hours, limit antibiotics to 24 hours only. 1

Special Situations

Biliary Infections

For community-acquired cholecystitis (mild-moderate), use cefazolin, cefuroxime, or ceftriaxone. 1

• For severe cholecystitis or cholangitis: Use imipenem-cilastatin, meropenem, piperacillin-tazobactam, or a fluoroquinolone plus metronidazole. 1
• Anaerobic coverage is NOT needed unless a biliary-enteric anastomosis is present. 1
• ERCP is the treatment of choice for biliary decompression in moderate/severe cholangitis. 1

Diverticulitis

For uncomplicated diverticulitis, conservative treatment WITHOUT antibiotics is appropriate in immunocompetent patients with CT confirmation. 1

• Use antibiotics for ≤7 days in immunocompromised or elderly patients with uncomplicated diverticulitis. 1
• For small diverticular abscesses (<4cm), antibiotics alone for 7 days may suffice. 1
• For large abscesses, percutaneous drainage plus antibiotics for 4 days is recommended. 1

Critical Pitfalls to Avoid

• Never delay antimicrobial therapy in critically ill patients—start immediately while arranging source control. 1, 2
• Do not use quinolones if local E. coli resistance exceeds 10% or if the patient received quinolones within 3 months. 1
• Do not continue antibiotics beyond 7 days when adequate source control has been achieved—this promotes resistance without improving outcomes. 1, 2
• Do not use overly broad empiric coverage (anti-MRSA, anti-VRE, anti-Pseudomonal) in community-acquired infections—this increases toxicity and resistance. 1
• Always obtain intraoperative cultures in hospital-acquired infections, critically ill patients, or those at risk for resistant pathogens to guide de-escalation. 1