- If the source of abscess is identified, location (e.g., site of perforation - stomach, duodenum, jejunum, ileum, appendix, or colon) defines likely flora.
- Enterobacterales (Escherichia coli, Klebsiella spp., Proteus spp., and Enterobacter spp.) and other gram-negative bacilli
- Anaerobes, including Bacteroides spp., Fusobacterium spp., Clostridium spp., Actinomyces spp., Peptostreptococcus spp. , etc.
- Enterococcus spp.
- Candida spp.
- Occasionally, gram-positive bacteria, including Staphylococcus aureus and Streptococci (Streptococcus anginosus group, including S. intermedius, S. constellatus, and S. anginosus).
- Inflammatory bowel disease, particularly Crohn’s disease, increase the risk of intra-abdominal and anorectal abscess and increased rates of recurrence.
- Healthcare-associated flora (Pseudomonas spp, resistant Enterobacterales, Candida spp.) are more likely when infections are complications of prior intra-abdominal 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 is 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.
- Intra-abdominal abscess may also develop after primary peritonitis (spontaneous bacterial peritonitis).
- History: fever, pain, nausea, vomiting, anorexia.
- 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.
- 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
- CT is most helpful due to good imaging quality and speed of acquisition.
- US and MRI are used occasionally.
- MRI is not used for drainage guidance.
- CT- or US-guided percutaneous should be considered for diagnostic confirmation, microbiological evaluation, and therapy in all cases.
- Where possible, percutaneous drainage of well-localized fluid collections is preferable to surgical drainage for diagnostic and therapeutic purposes.
- The complication rate of percutaneous abscess drainage is low (~2.5%) but should be considered when managing patients.
- Surgical drainage may be necessary if the source of intestinal leakage is not controlled.
Primary therapy: abscess drainage
- CT or US-guided percutaneous needle aspiration with subsequent catheter drainage is considered by many as 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 Enterobacterales, 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 based on the abscess and blood culture results.
- Isolation of Candida may not require treatment if the patient is improving without antifungal therapy.
- May modify antibiotic treatment once cultures have returned.
- May transition to an oral regimen once clinical improvement has been achieved in selected patients.
- Mild-moderate infection
- Ticarcillin/clavulanate 3.1g IV q6h (no longer available in the U.S.)
- Ertapenem 1g IV q24h
- Moxifloxacin 400 mg IV/PO q24h
- Additional monotherapy option: tigecycline 100 mg IV x 1, then 50 mg IV q12h. Useful for patients with allergy issues or multitude-resistant organisms; see selected drug comments below.
- Severe and/or nosocomial infections
- Alternatives: combination therapy
- Consider adding IV Vancomycin for patients with healthcare-associated intra-abdominal infection or known to be colonized with MRSA.
- Additional considerations:
- Empiric vancomycin-resistant Enterococcus (VRE) coverage is not recommended unless the patient is at high risk for VRE infection (for example, liver transplant recipient or hepatobiliary infection) or is known to be colonized with VRE. In such cases, linezolid or daptomycin can be included in the empiric regimen.
- Empiric antifungal therapy should be considered in patients with a high risk of developing invasive fungal infections, such as critical illness, recent abdominal surgery (especially upper GI tract), hematological malignancy, and organ transplantation. An echinocandin (anidulafungin, caspofungin or micafungin) or voriconazole is preferred due to possible azole-resistant organisms in such situations while awaiting yeast identification and susceptibility testing.
- Duration: after adequate drainage, at least 4-7 days of antibiotic coverage is indicated, with duration in part based on the resolution of fever and leukocytosis, severity of infection, and additional indicators of clinical response.
- The 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 may be appropriate.
- Duration of antibiotic therapy for an inadequately drained abscess with residual fluid may require prolonged therapy with follow-up imaging to ensure resolution. Still, sufficient data are lacking to support this approach entirely.
Selected Drug Comments
Increased resistance rates among isolates such as E. coli make 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 Enterobacterales 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, doesn’t provide coverage for Pseudomonas aeruginosa. Also no enterococcal coverage, unlike imipenem.
Excellent coverage of gram-negative including many P. aeruginosa, and gram-positive pathogens; use in combination with an 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.
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, we would only use it for mild-moderate infections empirically. This agent is no longer available in the U.S. marketplace.
Glycyltetracycline has broad coverage (gram positives 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 various infections, including IAIs.
It offers excellent anaerobic coverage and should be used 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.
While better tolerated than its cousin in the tetracycline class, tigecycline, and available in IV and oral forms, it is FDA-approved only for CABP and ABSSSI. Its broad spectrum of activity includes Gram negative and Gram positive aerobes and anaerobic pathogens, but like other tetracyclines doesn’t cover Proteus, Providencia, Morganella or Pseudomonas.
This carbapenem in the U.S. was 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 and gram-positive coverage; use in combination with an anaerobic agent (plus/minus an agent covering Enterococcus species) for empiric therapy in community-acquired intra-abdominal infections.
- Source control is essential. The open abdomen approach is occasionally necessary for severe infections.
- On-demand re-laparotomy rather than a planned re-laparotomy may be associated with better results in selected cases.
- If there is no clinical response within 3-5 days of antibiotic therapy and drainage, consider re-imaging to assess for undrained collections, inadequate coverage of resistant pathogens, or other cause not directly related to the abscess.
- Follow-up CT scans/US and/or sinograms are often needed to demonstrate the resolution of the source and abscess.
- Functional clinical parameters for assessment 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 immunosuppressant therapy may be appropriate soon after percutaneous drainage.
- Multiple factors, including the severity of illness, bacteremia, multiple abscesses, and location of the abscess, are predictive of mortality (even with treatment, mortality may still approach 30% depending on the population).
- Percutaneous drainage should be utilized whenever possible for source control when drainage is indicated.
- The 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 the patient is not clinically improving or repeated recovery of yeast from cultures.
- Empiric coverage of yeast and enterococci in adults with community-associated intra-abdominal infection is unnecessary.
- Consideration of these organisms is reasonable if clinical response is not as expected.
Pathogen Specific Therapy
Penicillin (high dose). 6-12 months of therapy
3rd generation cephalosporins, fluoroquinolones
Basis for recommendation
- Thompson DT, Hrabe JE. Intra-abdominal and Anorectal Abscesses. Gastroenterol Clin North Am. 2021;50(2):475-488. [PMID:34024453]
Comment: Review of intra-abdominal and anorectal abscesses.
- Montravers P, Tubach F, Lescot T, et al. Short-course antibiotic therapy for critically ill patients treated for postoperative intra-abdominal infection: the DURAPOP randomised clinical trial. Intensive Care Med. 2018;44(3):300-310. [PMID:29484469]
Comment: Short course (8 days) antibiotic therapy in post-operative intra-abdominal infections with adequate source control has a similar benefit to a longer course (15 days) without affecting the outcome.
- Mazuski JE, Tessier JM, May AK, et al. The Surgical Infection Society Revised Guidelines on the Management of Intra-Abdominal Infection. Surg Infect (Larchmt). 2017;18(1):1-76. [PMID:28085573]
Comment: Current revised guidelines on the management of intra-abdominal infection
- Akingboye AA, Mahmood F, Zaman S, et al. Early versus delayed (interval) appendicectomy for the management of appendicular abscess and phlegmon: a systematic review and meta-analysis. Langenbecks Arch Surg. 2021;406(5):1341-1351. [PMID:33416987]
Comment: The limited studies of 2 RCTs and four observational trials compared emergency appendectomy vs. interval appendectomy in the subset of people with appendicitis who also have abscesses. Those who had emergency surgery had a greater risk for subsequent bowel resection and more extended operations however there was no difference in post-op infections, size of the remaining collection, LOS or mortality.
- 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 are available, and all are observational. The 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. In 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 an 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.
- 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 maybe a temporary measure for those who need operative intervention. Complication rates of PAD are relatively uncommon.
- 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.
- Sung HY, Lee IS, Kim SI, et al. Clinical features of abdominal actinomycosis: a 15-year experience of a single institute. J Korean Med Sci. 2011;26(7):932-7. [PMID:21738348]
Comment: A 15-year review of clinical features of abdominal actinomycosis and therapeutic outcome at a Korean hospital.
- 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 the use of imaging modalities for LLQ pain utilizing ACR appropriateness criteria; includes case examples.
- 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: 2010 IDSA, SIS, ASM, and SIDP consensus guidelines archived after ten years.
- 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.
- 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 the need for percutaneous drainage vs. antibiotic therapy alone.
- Brook I. Intra-abdominal, retroperitoneal, and visceral abscesses in children. Eur J Pediatr Surg. 2004;14(4):265-73. [PMID:15343468]
Comment: A review describes microbiology, diagnosis, and managing intra-abdominal abscesses in children.
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