ID Grand Rounds - Stanford University Woman, 58, with Fever and Abdominal Pain
By Dana Clutter MD,
Postdoctoral Fellow in Infectious Diseases , Stanford University
Dr. Clutter reports no financial relationships in this field of study.
A 58-year-old woman from Southern Australia with a history of medically-managed liver abscess eight months prior to admission and recurrent urinary tract infections presented to our hospital with two weeks of fever and right upper quadrant pain. She initially presented to an outside hospital with fever, and was treated with norfloxacin for a presumed urinary tract infection. Despite this treatment, her fevers persisted and were associated with fatigue, arthralgias and night sweats. One day prior to admission she developed severe, constant right upper quadrant pain that was worse -with any movement. She denied any nausea, vomiting, diarrhea, dysuria, flank pain, or jaundice.
Her past medical history was notable for a liver abscess eight months prior to presentation that was not aspirated, but that was treated in Australia with one month of an unknown course of antibiotics. She also had a history of nephrolithiasis associated with recurrent urinary tract infections, Plasmodium vivax malaria, and irritable bowel syndrome. On arrival she was not taking any medications, but had just completed a 2-week course of norfloxacin. Regarding potential exposure history, she was visiting her daughter in California. She had an extensive travel history, including sub-Saharan Africa and Indonesia. Her hobbies include fly-fishing, and she eats wild game and raw fish regularly.
Physical Examination
On physical examination, her temperature was 37.3 °C, blood pressure was 98/43 mmHg, heart rate was 78 beats per minute, and respiratory rate was 16 breaths per minute.
Thin and in no acute distress, she had significant right upper quadrant tenderness with voluntary guarding and hypoactive bowel sounds.
The remainder of her examination was normal.
Lab Tests, Clinical Management
Laboratory investigations revealed a leukocytosis with 17.3 white blood cells/ìL (74% neutrophils), AST 64 U/L, ALT 31 U/L, alkaline phosphatase 222 U/L, normal bilirubin, albumin 2.2 g/dL, and protein 7.1 g/dL. Her urinalysis showed no pyuria. A CT scan of her abdomen with intravenous contrast showed a hypodense lesion with a surrounding halo measuring 4.5 x 5.5 cm in the right hepatic lobe, as well as two smaller satellite lesions.
On the day of admission, the patient underwent ultrasound-guided aspiration of the dominant liver abscess. Trichrome stain of the abscess fluid revealed neutrophils, red blood cells, and trophozooites containing ingested red blood cells, morphologically consistent with Entamoeba species Her serum was positive for Entamoeba histolytica IgG and she was diagnosed with amebic liver abscess.
She received treatment for amebiasis with oral metronidazole for 10 days, followed by one week of paromomycin. By the time of discharge, her abdominal pain had improved and her fevers had resolved.
Discussion
Entamoeba histolytica is a protozoan parasite for which humans are the only known host. It is transmitted via the fecal-oral route, and exists in two forms: cysts and trophozooites. Worldwide, there are 34-50 million symptomatic cases of amebiasis per year and up to 100,000 deaths. In the US, major risk factors include travel to an endemic area, and institutionalization. Amebic liver abscess is much more common in men than in women (10:1), has a predilection for the right hepatic lobe, and often presents as a solitary abscess. Amebic liver abscesses are associated with other GI symptoms in 10-35% of cases . 1The recommended diagnostic approach in suspected amebiasis includes both microscopy and serology because the sensitivity of either test alone is suboptimal. The mainstay of therapy for invasive amebiasis consists of oral metronidazole for 7-10 days or oral tinidazole for 5 days. Because 40%-60% of patients treated with a nitroimidazole will have persistent luminal disease, a 7-day course of paromomycin following nitroimidazole treatment is needed.2
When there is uncertainty surrounding the cause of a liver abscess, diagnostic aspiration is recommended. The same is true for complicated amebic liver abscesses. These are defined as amebic liver abscesses greater than 5cm in diameter, those in the left hepatic lobe, those with bacterial superinfection, or multiple amebic liver abscesses. Although conventional teaching advises against drainage of uncomplicated amebic liver abscesses, a 2009 Cochrane review on the subject found that the studies available were small, had suboptimal methods, and had findings that were too heterogeneous for meaningful conclusions to be drawn.3
Diagnosis: Amebic liver abscess.
Acknowledgements: The following participated in the care of the patient: Trip Sweeney, Niaz Banaei, Sean Collins, Andrew Zolopa.
References
- Haque, R., et al. Amebiasis. N Engl J Med 2003;348(16):1565-1573.
- Mandell, G. L., et al. Mandell, Douglas, and Bennett’s principles and practice of infectious diseases. 2010 Philadelphia, PA, Churchill Livingstone/Elsevier.
- Chavez-Tapia, N. C., et al. Image-guided percutaneous procedure plus metronidazole versus metronidazole alone for uncomplicated amoebic liver abscess. 2009 Cochrane Database Syst Rev(1): CD004886.
