Background
Microbiology
- Pyogenic
- Gram-negative bacteria
- Escherichia coli
- Klebsiella species
- Less common: Pseudomonas aeruginosa, Proteus, Enterobacter, Citrobacter, and Serratia
- Gram-positive bacteria
- Streptococcus species, especially Streptococcus anginosus group
- Enterococcus species
- Other Viridans group streptococci
- Less common Staphylococcus aureus and Streptococcus pyogenes
- Anaerobes
- Bacteroides species
- Less common: Fusobacterium, anaerobic streptococci, Clostridium species, Lactobacillus
- Fungi (rare): Candida species
- Gram-negative bacteria
- Amebic
Pathophysiology
- Pyogenic
- Biliary: most common mechanism, includes ascending cholangitis
- Hematogenous via hepatic artery: from bacteremia
- Hematogenous via portal vein: from an infection abdominal organ duch as diverticulitis, pancreatitis, or appendicitis
- Contiguous spread
- Trauma: including things like ingested toothpicks
- Cryptogenic: second most common mechanism is "unknown"
- Amebic: see Entamoeba histolytica
Risk Factors
- Likely more common in diabetes mellitus, cardiopulmonary disease, malignancy, and cirrhosis
- Neutrophil dysfunction, including chronic granulomatous disease
- Hemochromatosis, especially for abscesses involving Yersinia enterocolitica
Clinical Manifestations
- Most common signs are fever, abdominal pain, leukocytosis, and an elevated alkaline phosphatase
- Often presents with fevers alone, however
- May also have weight loss, diarrhea, RUQ tenderness, and jaundice
- The classic triad is considered to be fever, jaundice, and RUQ tenderness
Investigations
- Blood cultures are about 50% sensitive
- Imaging with ultrasound or CT is important
- Consider Entamoeba histolytica serology to rule out amoebic liver abscess, since the syndromes cannot reliably be distinguished clinically
Management
- Get source control
- Antibiotics should be broad-spectrum, such as piperacillin-tazobactam, ertapenem or meropenem, ceftriaxone plus metronidazole, or ciprofloxacin plus metronidazole
- Treat for 4-6 weeks total, ensuring radiological resolution of abscess
- Can step down to oral therapy after 2 to 3 weeks if responding appropriately
