Bacterial, Parasitic, and Fungal Infections of the Liver, Including Liver Abscesses Flashcards
Amebiasis (Entamoeba histolytica)
Worldwide, especially Africa, Asia, Mexico, South America
Hematogenous spread and tissue invasion, abscess formation
Fever, RUQ pain, peritonitis, elevated right hemidiaphragm, rupture
Cysts in stool, serology (e.g., ELISA, CIE, IHA), hepatic imaging
Metronidazole 750 mg (oral or IV) 3 times daily × 7-10 days or tinidazole 2 g × 3 days, followed by iodoquinol 650 mg 3 times daily × 20 days or diloxanide furoate 500 mg 3 times daily × 10 days or aminosidine (paromomycin) 25-35 mg/kg/day in 3 divided doses × 7-10 days
Ascariasis (Ascaris lumbricoides)
Tropical climates
Ingestion of raw vegetables
Migration of larvae to the liver; invasion of the bile ducts by adult worms
Abdominal pain, fever, jaundice, biliary obstruction, granulomas
Ova or adult in stool or contrast study
Albendazole 400 mg × 1 dose; or mebendazole 100 mg twice daily × 3 days; or pyrantel pamoate 11 mg/kg up to 1 g; or ivermectin 200 μg/kg × 1 dose
Schistosomiasis (Schistosoma mansoni, S. japonicum)
Asia, Africa, South America, Caribbean
Travelers exposed to bodies of fresh water
Fibrogenic host immune response to eggs in the portal vein
Acute: eosinophilic infiltrate
Chronic:
hepatosplenomegaly, presinusoidal portal hypertension, granulomas
Ova in the stool, rectal or liver biopsy
Praziquantel 40-60 mg/kg in 2-3 divided doses × 1 day; or oxamniquine for S. mansoni (not readily available)
Acute toxemic schistosomiasis: praziquantel 40-60 mg/kg in 2-3 divided doses × 1 day + glucocorticoids
Clonorchiasis and opisthorchiasis (Clonorchis sinensis, Opisthorchis viverrini, O. felineus)
Southeast Asia, China, Japan, Korea, Eastern Europe
Ingestion of raw fresh- water fish
Migration through
the ampulla; egg deposition in the bile ducts
Biliary hyperplasia, obstruction, sclerosing cholangitis, stone formation, cholangiocarcinoma
Ova in the stool, flukes in the bile ducts at ERC or surgery
Praziquantel 75 mg/kg in 3 divided doses × 1 day
Pyogenic
Often multiple
Either lobe of liver
Subacute presentation
Mild jaundice
US or CT ± aspiration
Drainage (if technically
feasible) + IV antibiotics
Amebic
Usually single
Usually right hepatic lobe, near the diaphragm
Acute presentation
Moderate jaundice
US or CT and serology
Metronidazole, 750 mg 3 times daily for 7-10 days orally or IV; or tinidazole, 2 g orally for 3 days, followed by iodoquinol, 650 mg orally 3 times daily for 20 days; diloxanide furoate, 500 mg orally 3 times daily for 10 days; or aminosidine (paromomycin) 25- 35 mg/kg/day orally in 3 divided doses for 7-10 days
Pyogenic
Most cases now are cryptogenic or occur in older men with underlying biliary tract disease.
Predisposing conditions include malignancy, immunosuppression, diabetes mellitus, and previous biliary surgery or interventional endoscopy.
Pyogenic liver abscess
Pyogenic liver abscess may arise as a late complication of endoscopic sphincterotomy for bile duct stones or within 3 to 6 weeks of a surgical biliary-intestinal anastomosis
The most frequently isolated organisms pyogenic abscess
The most frequently isolated organisms are Escherichia coli and Klebsiella, Proteus, Pseudomonas, and Streptococcus species, particularly the Streptococcus milleri (anginosus) group.
the most commonly identified anaerobic species are Bacteroides fragilis and Fusobacterium necrophorum; anaerobic streptococci have also been identified.
Hepatic abscesses
Hepatic abscesses are usually hypodense on a CT and may display a rim of contrast enhancement in less than 20% of cases
inflammatory pseudotumor of the liver
(also called plasma cell granuloma) is a rare, benign lesion characterized by proliferating fibrous tissue infiltrated by inflammatory cells. The cause is unknown. Affected persons (typically young men) often have a history of recent infection, but a causative infectious agent is rarely isolated from the lesion.
Treatment of a hepatic abscess(pyogenic)
requires antibiotic therapy directed at the causative organism(s) and, in most cases, drainage of the abscess, usually percutaneously with imaging guidance.
An indwelling drainage catheter may be placed in the abscess until the cavity has resolved, particularly for lesions greater than 5 cm in size, although intermittent needle aspiration may be as effective as continuous catheter drainage for smaller lesions
Medical management
Initial antibiotic coverage, pending culture results, should be broad in spectrum, as with a third-generation cephalosporin, or fluoroquinolone plus metronidazole, to cover anaerobic organisms.
Amebic
During its life cycle, Entamoeba histolytica exists as trophozoite or cyst forms.
After infection, amebic cysts pass through the GI tract and become trophozoites in the colon, where they invade the mucosa and produce typical “flask-shaped” ulcers.
The organism is carried by the portal vein circulation to the liver, where an abscess may develop.
Diagnosis
The diagnosis of amebic liver abscess is based on clinical suspicion, hepatic imaging, and serologic testing. The organism is isolated from the stool in only 50% of patients.
Hepatic imaging studies cannot distinguish a pyogenic from an amebic liver abscess
An amebic abscess is commonly localized to the right hepatic lobe, close to the diaphragm, and is usually single
