What is the recommended management for a patient with an intraabdominal abscess, including antibiotic therapy and supportive care?

Management of Intraabdominal Abscess

Intraabdominal abscesses require combined source control (percutaneous drainage or surgery) plus broad-spectrum antibiotics covering gram-negative aerobes, anaerobes, and gram-positive cocci for 4 days in stable patients with adequate drainage, or up to 7 days in critically ill patients. 1, 2

Source Control Strategy

Size-based drainage approach:

• Small abscesses (<3-4 cm): May be treated with antibiotics alone in clinically stable patients without sepsis 1
• Large abscesses: Require percutaneous image-guided drainage plus intravenous antibiotics 1
• When percutaneous drainage is not feasible or available: Antibiotics alone can be attempted in stable patients, but careful clinical monitoring is mandatory 1
• Surgical intervention: Reserved for failed percutaneous drainage, multiple loculated abscesses, or critically ill patients with diffuse peritonitis 1

Antibiotic Selection by Patient Severity

Non-Critically Ill, Immunocompetent Patients (Community-Acquired)

First-line regimens: 2

• Piperacillin-tazobactam 3.375-4.5 g IV every 6-8 hours
• Ertapenem 1 g IV daily
• Eravacycline 1 mg/kg IV every 12 hours

Alternative combinations: 1

• Ceftriaxone 1-2 g IV daily + Metronidazole 500 mg IV every 8 hours
• Cefepime 2 g IV every 8-12 hours + Metronidazole 500 mg IV every 8 hours

Critically Ill Patients or Healthcare-Associated Infections

Carbapenem-based regimens (normal renal function): 1

• Meropenem 1 g IV every 8 hours (by extended infusion or continuous infusion preferred)
• Imipenem/cilastatin 1 g IV every 8 hours (by extended infusion)
• Doripenem 500 mg IV every 8 hours (by extended infusion)

Carbapenem-sparing alternatives: 1

• Ceftolozane/tazobactam 1.5 g IV every 8 hours + Metronidazole 500 mg IV every 6 hours
• Ceftazidime/avibactam 2.5 g IV every 8 hours + Metronidazole 500 mg IV every 6 hours

Add gram-positive coverage if healthcare-associated or risk factors present: 1

• Vancomycin 25-30 mg/kg loading dose, then 15-20 mg/kg every 8 hours
• Teicoplanin 12 mg/kg every 12 hours × 3 doses, then 12 mg/kg daily

For vancomycin-resistant enterococci (VRE) risk: 1

• Linezolid 600 mg IV every 12 hours
• Daptomycin 6 mg/kg IV daily

Patients with Suspected Multidrug-Resistant Organisms

Risk factors include: Previous antimicrobial therapy, ICU stay >1 week, healthcare acquisition, organ transplantation, corticosteroid use 1

MDR-targeted regimens: 1

• Imipenem/cilastatin-relebactam 1.25 g IV every 6 hours (by extended infusion)
• Meropenem/vaborbactam 2 g/2 g IV every 8 hours (by extended infusion)
• Ceftazidime/avibactam 2.5 g IV every 8 hours + Metronidazole 500 mg IV every 8 hours

Plus gram-positive coverage: 1

• Linezolid 600 mg IV every 12 hours
• Teicoplanin 12 mg/kg every 12 hours × 3 loading doses, then 6 mg/kg every 12 hours

Beta-Lactam Allergy

Alternative regimen: 1, 2

• Eravacycline 1 mg/kg IV every 12 hours

Antifungal Coverage

Add empiric antifungal therapy in high-risk patients: 1

Risk factors: Upper GI perforation, recurrent GI perforation, recent broad-spectrum antibiotics, immunosuppression, ICU stay >7 days 1

Preferred agents: 1

• Caspofungin 70 mg IV loading dose, then 50 mg IV daily
• Anidulafungin 200 mg IV loading dose, then 100 mg IV daily
• Micafungin 100 mg IV daily
• Liposomal amphotericin B 3-5 mg/kg IV daily (if 1,3-beta-D-glucan testing available, use as preemptive therapy)

Duration of Therapy

Standard duration: 1, 2

• 4 days after adequate source control in immunocompetent, non-critically ill patients with clinical improvement
• Up to 7 days in critically ill or immunocompromised patients based on clinical response and inflammatory markers (CRP, procalcitonin)

Reassess at day 7: If ongoing signs of peritonitis or systemic illness persist beyond 5-7 days, investigate for uncontrolled source or treatment failure rather than simply continuing antibiotics 1

Critical Pitfalls to Avoid

Do NOT use these agents due to resistance: 2

• Ampicillin-sulbactam (high E. coli resistance rates)
• Cefotetan (increasing Bacteroides fragilis resistance)
• Clindamycin monotherapy (increasing B. fragilis resistance)
• Fluoroquinolones as first-line (widespread resistance in many regions) 1

Antibiotic penetration concerns: 3

• Vancomycin and ciprofloxacin achieve inadequate concentrations in most abscesses
• Fluconazole requires higher doses in all abscesses
• Piperacillin/tazobactam, cefepime, and metronidazole provide adequate concentrations except in the largest abscesses

Supportive Care

Fluid resuscitation: 1

• Early aggressive fluid resuscitation in septic patients
• Vasopressor support if fluid resuscitation alone fails

Monitoring parameters: 1

• Vital signs continuously in severe cases
• White blood cell count, C-reactive protein, procalcitonin
• Hematocrit, blood urea nitrogen, creatinine

Nutritional support: 1

• Enteral nutrition preferred (oral, nasogastric, or nasojejunal)
• Parenteral nutrition if enteral not tolerated

De-escalation Strategy

Narrow antibiotics based on culture results when available 2

• Transition from empiric broad-spectrum to targeted therapy once organisms identified
• Discontinue antifungal therapy if cultures negative and patient improving
• Stop gram-positive coverage if not isolated and patient stable