JOURNAL OF THE LOUISIANA STATE MEDICAL SOCIETY
REFERENCES
There are several laboratory tests available to confirm the diagnosis of amebiasis. Stool ova and parasites studies, which are commonly used in resource poor areas, only have a sensitivity of 25-60% in amoebic colitis and a sensitivity <10% in patients with ALA. 1,6 In patients not from endemic areas, anti- amoebic serum serology tests are often the preferred method of diagnosis. There are numerous commercially available antibody assays which have sensitivities of 93.3-100% and specificities of 90.9-100%. There are also commercially available stool, serum, and ALA purulence antigen testing kits which have sensitivities of 54.5-100% and specificities of 93-100%. 1 Entamoeba PCR primers are also available which, unlike most antibody and antigen assays, can distinguish Entamoeba specieis in stool and ALA purulence samples. 1,3 In non-endemic areas, patients with asymptomatic colonic amebiasis should be treated with a luminal agent that will kill amoebic cysts and trophocytes. The preferred luminal agents in the United States are paramomycin or iodoquinol, although a third agent, diloxanide furorate, can be used, but it has limited availability. 13 If a patient has symptomatic amebic colitis or disseminated amebiasis, such as an ALA, a nitroimidazole agent is given inaddition toa luminal agent.Thefirst linenitroimidazole agent is metronidazole. Alternatives to metronidazole include secnidazole, which is not available in the United States, and tinidazole. If a patient cannot tolerate or fails treatment with a nitroimidazole, chloroquine can be used instead. By the time an ALA is diagnosed, most patients will no longer have amoebic trophocytes or cysts in their colon. Failure to give ALA patients a luminal agent concomitantly with a nitromidazole can result in hepatic reinfection in up to 10% of cases. 13,15 Symptoms in patients with a liver abscess frequently improve within 72 hours of initiating metronidazole. 14 If not treated, there is a risk of spontaneous abscess rupture which, depending on the location, can drain into the peritoneum, pleural cavity, pericardium, or biliary tree. Such spontaneous ruptures can be fatal. 16 Although anti-amoebic agents are the primary treatment of ALA, percutaneous drainage is indicated if a patient does not improve within 3-7 days of initiating anti-amoebic therapy, if the abscess has a wall thicker than 10 mm, if the abscess is larger than 5 cm, or if the abscess is in the left hepatic lobe. 13,16 After initiating treatment, some ALA may resolve in as little as three months, but most will take six-nine months to fully resolve. Due to the gradual resolution of the cysts, as long as the patient remains asymptomatic, serial ultrasounds of the liver are not indicated. 16 Patients who undergo percutaneous drainage of their abscess are more likely to have resolution of the abscess sooner than those who only receive medical management. Ultimately, long-term sequelae of properly treated ALA are rare. 13
1. Fotedar R, Stark D, Beebe N, et al. Labroratory disagnostic techniques for Entamoeba species. Clin Microbiol Rev. 2007;20:511-32. 2. Wuerz T, Kane JB, Boggild AK, et al. A review of amoebic liver abscess for clinicians in a nonendemic setting. Can J Gastroenterol . 2012;26:729-33. 3. Ximenez C, Cerritos R, Rojas L, et al. Human amebiasis: breaking the paradigm? Int J Environ Res Public Helath . 2010;7:1105-20. 4. Oliveira FM, Neumann E, Gomes MA, Caliari MV. Entamoeba dispar: could it be pathogenic. Trop Parasitol . 2015;5:9-14. 5. Nanda R, Baveja U, Anand BS. Enatmoeba histolytica cyst passers: clinical features and outcome in untreated subjects. Lancet . 1984;11:301-3. 6. Petri WA, Singh U. Diagnosis and management of amebiasis. Clin Infect Dis. 1999;29:1117-25. 7. Ross AGP, Olds GR, Cripps AW, Farrar JJ, McManus DP. Enteropathogens and chronic illness in returning travelers. N Engl J Med . 2013;368:1817-25. 8. Wilson IW, Weedall GD, Hall N. Host-parasite interactions in Entamoeba histolytica and Entamoeba dispar: what have we learned from their genomes? Parasite Immunol . 2012;34:90-9. 9. Fernandez-Diez, Magana M, Magana ML. Cutaneous amebiasisis: 50 years of experience. Cutis . 2012;90:310-4. 10. Maldonado-Barrera CA, Campos-Esparza MR, Munoz-Fernandez L, et al. Clinical case of cerebral amebiasis cause by E. histolytica. Parasitol Res . 2012;110:1291-6. 11. Abdel Razek AA, Watcharakorn A, Castillo M. Parasitic deiseases of the central nervous system. Neuroimaging Clin N Am . 2011;21:815-41. 12. Shamsuzzaman SM, Hashiguchi Y. Thoracic amebiasis. Clin Chest Med. 2002;23:479-92. 13. Hughes MA, Petri WA. Amebic liver abscess. Infect Dise Clin North Am . 2000;12:565-82. 14. Blessmann J, Binh HD, Hung DM, Tannich E, Burschard G. Treatment of amoebic liver abscesss with metronidazole alone or in combination with ultrasound-guided needle aspiration: a comparative, prostpective and randomized study. Trop Med Int Health . 2003;8:1030-4. 15. Irusen EM, Jackson TF, Simjee AE. Asymptomatic intestinal colonization by pathogenic Entamoeba histolytica in amoebic lives abscess: prevalence, rersponse to therapy and pathogenic potential. Clin Infect Dis . 1992;14:889- 93. 16. Sharma MP, Ahuja V. Amebiasis. N Engl J Med . 2003;349:307-8. Dr. Liszewski was a preliminary medicine intern at LSUHSC-New Orleans, and is currently a resident in the Department of Dermatology at the University of Minnesota. Dr. Walvekar is an Assistant Professor in the Department of Medicine at LSUHSC-New Orleans. Dr. Lopez is the Richard Vial Professor and the Vice Chair of the Department of Medicine at LSUHSC-New Orleans.
108 J La State Med Soc VOL 169 JULY/AUGUST 2017
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