A. Diagnosis

1. Variable Abdominal Pain, usually high fevers
2. Slightly elevated AST (SGOT) and ALT (SGPT), both <100)
3. Total Bilirubin Slightly elevated
4. Computerized tomographic (CT) and ultrasound show hepatic abscess.
5. Blood cultures are positive in ~50% of cases

B. Differential Diagnosis of Liver Mass

1. Pyogenic abscess
2. Amebic abscess [3,4]
3. Tumor
   1. Colon metastasis
   2. Gastric CA
   3. Lymphoma
4. Infarction
5. Cyst

C. Etiology

1. Sepsis
2. Intravenous drug abuse (IVDA)
3. Immunocompromise
4. Amebic Infection

D. Causative Organisms

1. Gram negative rods (GNR): E. coli, Klebsiella pneumoniae, anaerobic bacilli (~50%)
2. Streptococcus milleri (frequent), anaerobic streptococci (especially Group D)
3. Infrequent: Staphylococcal ssp., Candida; usually via extrahepatic routes
4. Burkholderia pseuomallei - cause of melioidosis
5. Entamoeba histolytica - amoebic abscess
6. Polymicrobial abscess

E. Melioidosis [5]

1. Caused by Burkholderia pseudomallei, a gram-negative rod
2. B. pseudomallei is a soil-based saprophyte that mainly infects adults with diabetes mellitus
3. Most common in East Asia, Northern Australia
4. Can progress to sepsis: causes 20% of community acquired sepsis in common areas
5. Melioidosis is characterized by multiple abscess: lung, liver, spleen, skeletal muscle, prostate
6. May present as parotid abscess in children (primarily from southeast Asia)
7. Ceftazidime is treatment of choice, but median of 9 days before fever breaks
8. Maintenance therapy with chloramphenicol, doxycycline, trimethoprim/sulfamethoxazole

F. Empiric therapy

1. Ampicillin /Gentamicin /Metronidazole (Ceftriaxone replaces Gentamicin)
2. Klebsiella oxytocia: ciprofloxacin, metronidazole
3. Amoebic: metronidazole 750mg tid x 10 days or tinidazole 2gms / day x 3 days
   1. Specific Therapy
4. Drainage: percutaneous, success 85%, mortality 4%
5. Open drainage: inaccessible percutaneously, coagulopathy, multiple abscess
6. Antibiotics, long term (6 weeks oral therapy or longer)
   1. Enteric aerobes: aminoglycosides
   2. Anaerobes: G- metronidazole (below diaphragm), ampicillin
   3. Streptococci: Penicillin or Ampicillin for aerobic and anaerobic streptococci
   4. Resistant anaerobic streptococci: metronidazole or Unasyn® or Timentin®
7. Amoebic Abscess [3,4]
   1. Requires up to 5-10 days of drug therapy, often 2 days sufficient
   2. Metronidazole 2.4gm divided daily x 2 days OR tinidazole 2gm qd po x 3 days
   3. Surgical drainage not required
   4. Aspiration only when diagnosis is in question

References

1. Indik JH and Masters L. 1998. Arch Intern Med. 158(12):1374 (Case Report)
2. Chu KM, Fan ST, Lai EC, et al. 1996. Arch Surg. 131(2):148
3. Stanley SL Jr. 2003. Lancet. 361(9362):1025
4. Haque R, Huston CD, Hughes M, et al. 2003. NEJM. 348(16):1565
5. White NJ. 2003. Lancet. 361(9370):1715