- Gram-positive cocci: Streptococcus spp (especially S. intermedius group), enterococci, and Staphylococcus aureus.
- Anaerobes: Bacteroides species, Fusobacterium sp, Actinomyces sp, Clostridium sp, etc.
- Enterobacteriaceae (E. coli, Klebsiella spp., etc) and other Gram negative bacilli.
- Yersinia enterocolitica: rare cause of liver abscess, consider underlying hemochromatosis.
- Candida species
- Entamoeba histolytica: amebic liver abscesses may complicate up to 10% of the cases of amebic colitis.
- Echinococcus granulosus: most common cause of hydatid cysts.
- Pyogenic hepatic abscesses generally occur in middle-aged adults (40’s and 50’s).
- Signs and symptoms: include fever +/- RUQ pain, tenderness w/ hepatomegaly.
- Some may only have fever (60%) associated with chills and malaise.
- Presentation may be subacute or chronic including weight loss, anorexia.
- Occasionally, patients may be acutely ill with mental status changes.
- Rarely, patients may present with sepsis and peritoneal signs from intraperitoneal rupture of the abscess.
- Approximately 50% of patients have a solitary hepatic abscess.
- Majority of abscesses involve in the right hepatic lobe (~75%), less commonly left (20%) or caudate (5%) lobes.
- Diaphragmatic irritation from abscess may refer pain to the right shoulder +/or cough or pleural rub.
- Classified by presumed origin:
- Up to 50% develop from biliary tract (cholangitis).
- Remainder are from hepatic artery (bacteremia), portal vein (abdominal source, e.g. diverticulitis), contiguous focus (local abscess or cholecystitis) or penetrating trauma.
- Many are of cryptogenic origin.
- Entamoeba histolytica: abscess occurs via the portal system during colitis.
- Typically manifests as a right lobe solitary lesion.
- Rare in the Untied States, occurring almost exclusively in immigrants and travelers.
- Men, especially MSM, at higher risk for invasive disease.
- Echinococcal, or hydatid cysts: most commonly caused by Echinococcus granulosus and usually acquired from canines (sheep dogs).
- Rarely seen in the United States.
- Usually asymptomatic until symptoms develop due to size of enlarging cyst or leakage/rupture.
- Underlying disease typically is the primary determinant of outcome.
- For pyogenic liver abscess(es), positive blood cultures are found in up to 50%, with alkaline phosphatase and WBC counts frequently elevated. Hyperbilirubinemia with or without jaundice occurs in < 50% of patients.
- Although dx may be suggested on plain films (e.g., gas within the abscess), CT, US, and MRI are the imaging modalities of choice in suspected liver abscess or FUO.
- CT or US-guided percutaneous drainage or surgical drainage should be considered in all cases of hepatic abscess for diagnostic confirmation and culture.
- Positive amebic or echinococcal serology helps differentiate parasitic liver abscess from pyogenic, especially in nonendemic areas. Serology cannot distinguish between active and prior infection.
- Uncomplicated small abscesses due to Entamoeba histolytica in endemic areas may not require aspiration; consider empirical rx.
Drainage and General Management
- Abscess drainage is the optimal therapy for pyogenic liver abscesses.
- Aspirate should be sent for gram stain and aerobic/anaerobic culture; evaluation for fungal and mycobacterial pathogens. E. histolytica should be considered based on epidemiologic factors.
- CT or US-guided percutaneous needle aspiration +/- catheter drainage initial method of choice:
- Success in up to 90% of cases.
- If drainage inadequate, surgical drainage may be required.
- Percutaneous aspiration without catheter placement: recently found to have similar success rates as catheter placement.
- Repeat aspiration required in approximately 50%.
- Catheter placement should be considered in larger abscesses (>5 cm diameter).
- Complications of percutaneous drainage: include perforation of adjacent abdominal organs, pneumothorax, hemorrhage and leakage of abscess contents in peritoneum.
- General recommendations are for at least one week of drainage with CT follow-up.
- Surgical drainage: may consider as primary treatment in certain settings.
- Complex abscess
- Multiple abscesses
- Percutaneously unreachable abscess
- Larger abscesses (> 5 cm)
- If associated surgical problem also present
- Drainage may be done laparoscopically
- Hepatotomy: generally successful approach, but improvements in percutaneous techniques make it secondary management in most cases.
- Medical management: consider in patients at high risk for drainage procedures or with small/multiple abscesses not amenable to drainage.
- Empiric coverage should include Enterobacteriaceae, enterococci, anaerobes, and in certain situations staphylococci and streptococci.
- In a stable patient antibiotics may be deferred until post-aspiration/drainage to increase culture yield.
- Consider empiric antifungal treatment in immunosuppressed patients at risk for chronic disseminated candidiasis (CDC, a.k.a. hepatosplenic candidiasis, also see C. albicans module).
- Culture results may help narrow coverage, but for pyogenic abscess do not discontinue anaerobic coverage given difficulty culturing these organisms.
- Empiric regimens: may narrow based on culture results.
- Ampicillin 2.0g IV q6h plus gentamicin 1.7mg/kg IV q8h plus metronidazole 0.5g IV q8h
- Cefotaxime 2.0g IV q8h or ceftriaxone 2.0g IV q24h plus metronidazole 0.5g IV q8h
- Piperacillin/tazobactam 3.375g IV q 6h
- Consider adding metronidazole if amebic liver abscess a possibility.
- Carbapenems: appropriate for monotherapy, especially if the patient is at high risk for resistant GNRs or has a documented multidrug-resistant organism.
- Fluroquinolones: often used as an oral regimen for prolonged therapy after completion of initial parenteral therapy course.
- Ciprofloxacin, levofloxacin or moxifloxacin plus metronidazole
- Duration: if adequate drainage achieved with resolution of fever and leukocytosis.
- Often 14-42 days total.
- Longer courses (up to several months) may be required in the patient who is inadequately drained or treated without drainage.
- Follow-up imaging studies: consider in patients with suboptimal clinical response.
- Use CT or ultrasound.
- Note: imaging findings may lag behind other clinical markers of response.
Amebic hepatic abscess
- See Entameoba histolytica module for additional details.
- Metronidazole 750mg PO three times a day x 7-10 days as a tissue agent, followed by a luminal agent to eliminate residual colonic colonization, usually paromomycin 500mg three times a day PO x 7d.
- Tissue agent: tinidazole 800mg three times a day or 2g +daily x 3-5d.
- Luminal agents:
- Iodoquinol 650mg three times a day x 20d
- Diloxanide furoate 500mg three times a day x 10d
- Percutaneous aspiration has no clear role in therapy, but consider for diagnosis if uncertain (serology inconclusive or not available) or no response to appropriate antibacterial therapy.
- Predictors of need for aspiration: include age> 55 years, abscesses > 5 cms, involvement of both lobes of liver and failure of medical therapy after 7 days.
Hydatid (Echinococcal) cyst
- Most commonly E. granulosus, see module for additional details.
- Serology usually helpful in most cases.
- In patients with rupture of the cyst in the biliary tree, transient but markedly elevated levels of alkaline phosphatase and bilirubin may occur. Hyperamylasemia and eosinophilia occur in up to 60%.
- Surgical resection standard intervention:
- Uncomplicated cysts: PAIR (Percutaneous puncture with CT or US guidance, followed by Aspiration, Injection of a protoscolicidal agent such as hypertonic saline or ethanol, and finally Re-aspiration 15 minutes later) is becoming more accepted treatment of choice at some centers due to high success rates with low morbidity.
- Open or percutaneous (PAIR) procedures should be combined with albendazole treatment.
Selected Drug Comments
Good coverage of Gram-positive, Gram-negative, and anaerobic pathogens - lacks Pseudomonas aeruginosa coverage but good Enterococcus species coverage. Rising rates of resistance in E. coli mean that this is no longer a favored empiric choice, but may be quite acceptable once culture results have returned.
Excellent coverage of gram negative w/ some Gram positive pathogens; use in combination with anaerobic agent for empiric therapy.
Excellent broad spectrum (Gram-positive, Gram-negative, and anaerobe) coverage; would reserve for seriously ill patients. Has better coverage for E. faecalis than meropenem or doripenem; none of the carbapenems cover E. faecium.
Excellent broad spectrum (gram-positive, gram-negative, and anaerobe) coverage; would reserve for seriously ill patients. Will cover E. faecalis; none of the carbapenems cover E. faecium.
Newer carbapenem approved recently for complicated IAIs. Excellent gram-positive (except E. faecium), Gram-negative and anaerobic coverage.
Excellent broad-spectrum coverage includes anaerobic activity, many would still use with metronidazole with liver abscess condition.
Excellent broad spectrum coverage including Gram-positive and Gram-negative coverage (including Pseudomonas aeruginosa and β-lactamase producing pathogens) and anaerobic coverage.
Broad spectrum coverage including Gram-positive coverage, Gram-negative coverage (including Pseudomonas aeruginosa [but less active than piperacillin/tazobactam] and B-lactamase producing pathogens) and anaerobic coverage.
Remains premier anti-anaerobic drug, and preferred for pyogenic abscesses in combination therapy, also treats amebic liver infection.
Broad spectrum agent related to minocycline, with excellent gram-positive (including MRSA and VRE), Gram-negative (except Pseudomonas aeruginosa and Proteus mirabilis) and anaerobic activity, approved for complicated intraabdominal infections.
- Untreated, the mortality rate associated with pyogenic hepatic abscess approaches 100%.
- With treatment, in some series, mortality is below 15%; the latter mortality is dependent upon underlying disease.
- Recurrence is more frequent after simple percutaneous aspiration without placement of a temporary drain, or in patients in whom drains are removed too early.
- Hepatic abscesses are frequently polymicrobial.
- Single/multiple lesions occur in approximately a 1:1 ratio, with the majority in the right lobe (especially when solitary); cryptogenic abscesses are generally solitary.
- Abscesses are frequently associated with chronic medical conditions (e.g., diabetes), hematologic disease (e.g., leukemia), and chronic granulomatous disease (Staphylococcus aureus).
- Chronic disseminated candidiasis (CDC, a.k.a. hepatosplenic candidiasis) occurs in immunosuppressed patients, e.g. bone marrow transplant recipients.
Pathogen Specific Therapy
1st Line Agent
2nd Line Agent
1st, 2nd, or 3rd generation cephalosporins
Entamoeba histolytica (amebic liver abscess)
Surgical resection or PAIR procedure
Basis for recommendation
- Author opinion
Comment: Recommendations in this module are based on literature given lack of robust RCT data and guideline statements.
- Lambertucci JR et al: Pyogenic abscesses and parasitic diseases. Rev Inst Med Trop Sao Paulo 43:67, 2001 Mar-Apr [PMID:11340478]
Comment: Association of underlying parasitic disease and superinfection with bacteria.
- Benedetti NJ, Desser TS, Jeffrey RB: Imaging of hepatic infections. Ultrasound Q 24:267, 2008 [PMID:19060716]
Comment: Review of imaging of hepatic abscesses and other hepatic infections.
- Yu SC et al: Treatment of pyogenic liver abscess: prospective randomized comparison of catheter drainage and needle aspiration. Hepatology 39:932, 2004 [PMID:15057896]
Comment: Compares catheter drainage versus needle aspiration.
- Kurland JE, Brann OS: Pyogenic and amebic liver abscesses. Curr Gastroenterol Rep 6:273, 2004 [PMID:15245694]
Comment: Review of the most common infectious causes of abscess disease in the liver.
- Nasseri-Moghaddam S et al: Percutaneous needle aspiration, injection, and re-aspiration with or without benzimidazole coverage for uncomplicated hepatic hydatid cysts. Cochrane Database Syst Rev [PMID:21249654]
Comment: No RCTs identified to support or refute role of PAIR procedure with or without benzimidazole for hydatid cysts.
- Khan R et al: Predictive factors for early aspiration in liver abscess. World J Gastroenterol 14:2089, 2008 [PMID:18395912]
Comment: Predictive factors for early aspiration in liver abscess
- Reid-Lombardo KM, Khan S, Sclabas G: Hepatic cysts and liver abscess. Surg Clin North Am 90:679, 2010 [PMID:20637941]
Comment: Contains a review of pyogenic (including a breakdown of pyogenic causes and microbiology) and parasitic (including hydatid cyst and amoebic) liver abscesses.
- Siu LK et al: Klebsiella pneumoniae liver abscess: a new invasive syndrome. Lancet Infect Dis 12:881, 2012 [PMID:23099082]
Provides an overview of clinical features and management of hepatic abscesses caused by Klebsiella.
- Solomkin JS et al: Guidelines for the selection of anti-infective agents for complicated intra-abdominal infections. Clin Infect Dis 37:997, 2003 [PMID:14523762]
Comment: Consensus, evidence-based general guidelines from IDSA, SIS, ASM, and SIDP.
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