Intra-abdominal Abscess


  • If source of abscess identified, location (e.g., site of perforation - stomach, duodenum, jejunum, ileum, appendix or colon) defines likely flora.
  • Health-care associated flora more likely when infections are complications of prior intraabdominal operations or procedures.


  • Broad range of presenting complaints:
    • Patients may only present with malaise/anorexia or weight loss.
    • Others present acutely ill in septic shock with localized pain or an acute abdomen.
  • Non visceral abscesses develop after gastrointestinal perforation from local disease (diverticulitis, etc.), trauma or surgical intervention.
    • Abscess known to occur in up to 40% of cases of acute complicated diverticulitis.
    • Subsequent secondary peritonitis then becomes walled off by inflammatory adhesions, loops of intestine, mesentery or omentum, and other abdominal viscera.
    • Intraabdominal abscess also may develop after primary peritonitis (spontaneous bacterial peritonitis).
  • History: fever, pain, nausea, vomiting, anorexia, abdominal pain.
  • PE: local tenderness, possibly a palpable mass; if postoperative, assessment for abscess confounded by analgesics, ileus and incisional pain; over half presenting within 10 days of initial operation.
  • Lab:
    • Elevated WBC common
    • Derangement of liver enzymes, elevated alkaline phosphatase or hypergammaglobulinemia depending on duration and location of the abscess (e.g., liver, gallbladder, etc.)
    • Blood cultures positive ~25% depending on site and severity
    • Direct aspiration yielding positive Gram stain/culture


  • Imaging:
    • CT most helpful.
    • US and MRI used occasionally.
      • MRI not used for drainage guidance.
  • CT- or US-guided percutaneous or surgical drainage should be considered in all cases for diagnostic confirmation, microbiological evaluation, and therapy.
    • Where feasible, percutaneous drainage of well-localized fluid collections is preferable to surgical drainage for diagnostic and therapeutic purposes.
    • Complication rate of percutaenous abscess drainage is low (~2.5%), but should be taken into account when managing patients.


Primary therapy: abscess drainage

  • CT or US-guided percutaneous needle aspiration with subsequent catheter drainage is considered by many as the first line therapy; if drainage is inadequate surgery may be required.
    • Surgery used primarily after percutaneous therapy has failed, after percutaneous therapy has stabilized the condition in preparation for primary surgical therapy, or when concurrent surgical source control needed.
    • Infected pancreatic necrosis not well suited to percutaneous therapy because of cellular debris.
  • If an abscess unrelated to a surgical procedure or other obvious source is encountered, must consider the possibility of an underlying necrotic cancer.
  • Antimicrobial therapy alone (without drainage or a surgical procedure) should be reserved for highly-selected patients with a relatively small (< 3 cm diameter), well-circumscribed area of infection and minimal physiological derangement, provided close monitoring and follow-up can be arranged.

Adjunctive antibiotic treatment

  • Empiric coverage (microbiologic source of infection unknown) should include coverage of Enterobacteriaceae, enteric Streptococci, and anaerobes.
    • Empirical coverage of Enterococci should be considered in hospital-acquired and healthcare-associated infections.
    • Empiric coverage may be broadened or cautiously narrowed on the basis of the abscess and blood culture results.
    • Isolation of Candida may not require treatment if patient is improving without antifungal therapy.
  • May modify antibiotic treatment once cultures have returned.
  • Mild-moderate infection
  • Severe and/or nosocomial infections
  • Duration: after adequate drainage, at least 4-7 days of antibiotic coverage is indicated, with duration in part based on resolution of fever and leukocytosis, severity of infection, and additional indicators of clinical response.
    • Duration of therapy has not been subjected to rigorous study.
    • If the underlying surgical problem or source has been difficult to control, a longer course of antibiotics maybe appropriate.
    • Duration of antibiotic therapy for an inadequately drained abscess with residual fluid may require prolonged therapy with follow-up imaging to ensure resolution, but sufficient data are lacking to fully support this approach.

Selected Drug Comments




Increased rates of resistance makes this a poor choice nowadays for empiric therapy. Historically good coverage of Gram-positive, Gram-negative, and anaerobic pathogens - lacks Pseudomonas aeruginosa and has diminished Enterobacteriaceae susceptibilities but good Enterococcus species coverage.


Excellent broad spectrum coverage including Gram-positive coverage, Gram-negative coverage (including Pseudomonas aeruginosa and beta-lactamase producing pathogens) and anaerobic coverage.


Good broad spectrum coverage including ESBL Gram-negatives and anaerobes, but doesn’t provide coverage for Pseudomonas aeruginosa. Also no enterococcal coverage unlike imipenem.


Excellent coverage of Gram-negative and Gram-positive pathogens; use in combination with anaerobic agent (plus/minus an agent covering Enterococcus species) for empiric therapy.


Excellent broad spectrum coverage including Gram-negatives and most anaerobes, but does not provide coverage for P. aeruginosa. Due to increasing Bacteroides resistance would only use for mild infections.

Ticarcillin/clavulanic acid

Historically excellent broad spectrum coverage including gram-positive coverage, gram-negative coverage (including Pseudomonas aeruginosa and B-lactamase-producing pathogens) and anaerobic coverage. Due to rising rates of Gram negative resistance, would only use for mild-moderate infections empirically. This agent is no longer available in the U.S. marketplace.


Glycyltetracycline with very broad coverage (Gram-positive including MRSA and VRE, Gram-negatives including Acinetobacter spp. but not P. aeruginosa or Proteus sp). Good choice in patients with high-grade beta-lactam allergy. Recent pooled analysis of clinical trials revealed an increased mortality risk compared with other antibiotics used to treat a variety of infections, including IAIs.


Offers excellent anaerobic coverage, should be used in combination with an agent covering GNRs and possibly Enterococcus species.


Excellent broad spectrum (Gram-positive, Gram-negative, and anaerobe) coverage; would reserve for seriously ill patients at high risk for resistant pathogens.


Excellent broad spectrum (Gram-positive, Gram-negative, and anaerobe) coverage; would reserve for seriously ill patients at high risk for resistant pathogens.


Newest carbapenem in the U.S., approved for complicated intra-abdominal infections in 2007. Excellent broad spectrum (Gram-positive, Gram-negative, including some carbapenem-resistant Pseudomonas species, and anaerobe) coverage, would reserve for seriously ill patients at high risk for resistant pathogens.


Very good Gram-negative coverage and Gram-positive coverage; use in combination with anaerobic agent (plus/minus an agent covering Enterococcus species) for empiric therapy


  • Source control is essential. The open abdomen approach is occasionally necessary in severe infections.
  • On-demand re-laparotomy rather than a planned re-laparotomy may be associated with better results in selected cases.
  • If no clinical response within 3-5 days of antibiotic therapy and drainage, consider re-imaging to assess for undrained collections or other processes such as resistant pathogens.
  • Follow up CT scan/US and/or sinograms are often needed to demonstrate resolution of source and abscess.
  • Useful clinical parameters to follow include imaging studies, temperature, white blood cell count and possibly serum C-reactive protein.
  • In select patients with spontaneous abscess from Crohn’s disease, reinstitution or optimization of immunosuppressants therapy may be appropriate soon after percutaneous drainage.


  • Multiple factors, including severity of illness, bacteremia, multiple abscesses, and location of abscess are predictive of mortality (even with treatment, mortality may still approach 30% depending on the population).
  • Percutaneous drainage should be utilized IF possible and surgical source is controlled.
  • Rate of recovery of yeast from intraoperative specimens of a perforated viscus was >30% and was associated with death and complications. Consider anti-fungal treatment if recovery of yeast from cultures and patient not clinically improving, or repeated recovery of yeast from cultures.
  • Empiric coverage of yeast and Enterococci is adults with community-associated intra-abdominal infection is not necessary.
    • Consideration of these organisms are reasonable if clinical response is not as expected.

Pathogen Specific Therapy


First-Line Agents

Second-Line Agents



Piperacillin/tazobactam, ticarcillin/clavulanic acid, ampicillin/sulbactam, imipenem, meropenem, doripenem, tigecycline, clindamycin.


3rd generation cephalosporins, fluoroquinolones

Pipercillin/tazobactam, ticarcillin/clavulanic acid, ampicillin/sulbactam, tigecycline, aminoglycosides, carbapenems for resistant pathogens


Penicillin or ampicillin +/- gentamicin

Vancomycin +/- gentamicin, linezolid, daptomycin, tigecycline


Penicillin or ampicillin

Cefazolin, etc.

Pseudomonas aeruginosa

Piperacillin, ceftazidime, cefepime

Imipenem, meropenem, doripenem; ciprofloxacin or levofloxacin (if susceptible)

Candida albicans or other Candida species

Echinocandins (caspofungin, micafungin, anidulafungin)

Amphotericin B or lipid formulation products,
voriconazole, posaconazole

Staphylococcus aureus


Nafcillin or oxacillin, cefazolin



Vancomycin, linezolid, daptomycin, tigecycline

Coagulase-negative Staphylococci


Linezolid, daptomycin, tigecycline

Basis for recommendation

  1. Solomkin JS, Mazuski JE, Bradley JS, et al. Diagnosis and management of complicated intra-abdominal infection in adults and children: guidelines by the Surgical Infection Society and the Infectious Diseases Society of America. Clin Infect Dis. 2010;50(2):133-64.  [PMID:20034345]

    Comment: IDSA, SIS, ASM, and SIDP consensus guidelines


  1. Gregersen R, Mortensen LQ, Burcharth J, et al. Treatment of patients with acute colonic diverticulitis complicated by abscess formation: A systematic review. Int J Surg. 2016;35:201-208.  [PMID:27741423]

    Comment: Limited studies available, all observational. Failure rate in this group of 8766 patients was ~ 20%, regardless of non-operative treatment choice. Abscesses < 3 cm were sufficiently treated with antibiotics alone. Patients without operative intervention, 25% experienced a recurrent episode during long-term follow-up. When comparing percutaneous drainage (PAD) to antibiotic treatment, PAD was superior (15.9% vs. 22.2% failure rates). Patients undergoing acute surgery had increased risk of death (12.1% vs. 1.1%) compared to patients treated non-operatively. Of patients undergoing PAD, 2.5% experienced procedure-related complications and 15.5% needed adjustment or replacement of the drain. These sorts of studies are very prone to bias, so interpret results with caution.

  2. Jaffe TA, Nelson RC. Image-guided percutaneous drainage: a review. Abdom Radiol (NY). 2016;41(4):629-36.  [PMID:26826090]

    Comment: PAD is now the routine and preferred approach and may be a temporazing measure for those who need operative intervention. Compliation rates of PAD are relatively uncommon.

  3. Feagins LA, Holubar SD, Kane SV, et al. Current strategies in the management of intra-abdominal abscesses in Crohn's disease. Clin Gastroenterol Hepatol. 2011;9(10):842-50.  [PMID:21679776]

    Comment: Reviews strategies for managing intra-abdominal abscesses in Crohn’s disease; includes a management algorithm and a discussion on immunosuppression management during infection.

  4. Hammond NA, Nikolaidis P, Miller FH. Left lower-quadrant pain: guidelines from the American College of Radiology appropriateness criteria. Am Fam Physician. 2010;82(7):766-70.  [PMID:20879699]

    Comment: Guidelines for use of imaging modalities for LLQ pain utilizing ACR appropriateness criteria; includes case examples

  5. Mazuski JE, Solomkin JS. Intra-abdominal infections. Surg Clin North Am. 2009;89(2):421-37, ix.  [PMID:19281892]

    Comment: Review of management of a variety of intra-abdominal infections.
    Rating: Important

  6. Kumar RR, Kim JT, Haukoos JS, et al. Factors affecting the successful management of intra-abdominal abscesses with antibiotics and the need for percutaneous drainage. Dis Colon Rectum. 2006;49(2):183-9.  [PMID:16322960]

    Comment: Retrospective review assessing need for percutaneous drainage vs. antibiotic therapy alone.

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Last updated: September 3, 2017