Hamid, Saeed

Jamil, Bushra

English

eCommons@AKU

eCommons@AKUDepartment of Medicine Department of MedicineJanuary 2002Abscesses in the liver: amoebic or pyogenic?Bushra JamilAga Khan University, bushra.jamil@aku.eduSaeed HamidAga Khan University, saeed.hamid@aku.eduFollow this and additional works at: https://ecommons.aku.edu/pakistan_fhs_mc_med_medPart of the Internal Medicine CommonsRecommended CitationJamil, B., Hamid, S. (2002). Abscesses in the liver: amoebic or pyogenic?. Journal of Pakistan Medical Association.Available at: https://ecommons.aku.edu/pakistan_fhs_mc_med_med/475Abscesses in the Liver: Amoebic or Pyogenic?B. Jamil,S. S. Hamid ( Departments of Medicine and Microbiology, The Aga Khan University Hospital, Karachi. ) Liver abscess is a common condition in our part of the world. This is not surprising if one looks at theepidemiology of amoebiasis. The prevalence of infection with E. histolytica and E. dispar is as high as50% in the underdeveloped areas, where asymptomatic intestinal infection occurs in 90 to 99% ofinfected individuals and confers a 10% risk per year of symptomatic invasive amoebiasis1. However,apart from Entamoeba histolytica, liver abscess may also be caused by other pathogens, includingenteric gram-negative bacteria and pyogenic gram-positive cocci. Occasionally, salmonella, brucella,mycobacteria and even fungi have been known to produce abscesses in the liver. Pyogenic liverabscess, however, is an uncommon entity. Not unexpectedly, it is more common than amoebic liverabscess in the developed world: a direct reflection of prevalence of E. histolytica in these areas2,3.How does a liver abscess evolve? The liver is prone to microbial invasion by virtue of its anatomicallocation and function. Most of the blood from the large gut drains into the right lobe of the liverthrough the portal system. Organisms passing through the hepatic sinusoids are trapped, phagocytosedand killed by the hepatic mononuclear-macrophage system. An abscess develops when thesephagocytic cells fail to eradicate the microbes, either because of some intrinsic defect in their functionor because of the virulence of the infecting organisms. Micoorganisms that evade phagocytosis andintracellular killing, subsequently inflict cellular injury, directly and/or through release of lytic enzymesand toxins.Conditions like appendicitis, diverticulitis or inflammatory bowel disease, where the infectious processis in the bed of the portal venous circulation, lead to pyogenic liver abscesses through suppurativethrombophlebitis. Apart from portal circulation, the liver may be infected from the biliary tract,secondary to a calculus, stricture or malignancy. Biliary disease is now the most common source ofpyogenic abscess4. Liver abscess can also arise from infection of the gall bladder, through the bloodstream from infected foci anywhere in the body, and following direct trauma. About one-fourth of thecases are cryptogenic, i.e., no source can be identified and are probably caused by infection of infractedportions of the liver. Pyogenic liyer abscesses may develop in patients with sickle cell anemia5 and asan infectious complication of liver transplantation6.Liver abscesses caused by E. histolytica complicate 3-9% of cases of amoebic colitis2. Although thereis no sex predominance in bacterial liver abscesses, more than 90% of amoebic liver abscesses occur inmen; patients with amoebic liver abscesses are generally younger than those with bacterial abscesses1.Pyogenic liver abscess is frequently polymicrobial and enteric gram-negative bacilli are generallycultured from the aspirated pus. The specific types of microorganisms that cause liver abscess probablyvary with the underlying disease. The high frequency of “sterile” abscesses, reported in some series tobe about 50% is probably a result of inadequate anaerobic cultivation. As a result of modern anaerobicbacteriologic techniques, anaerobic bacteria are now recognized as a major cause of liver abscesses.When modern anaerobic culture techniques are used, about 50% of all pyogenic liver abscesses havebeen found to be caused by anaerobes7 with positive blood cultures in 54% of these cases.Staphylococcus aureus and group A streptococcus account for 20% or less of cases. Candida mayinvade the liver as part of a systemic infection in patients with acute leukemia and producemicroabscesses.In the past, it was believed that 10-20% of amoebic liver abscesses were secondarily infected withbacteria, usually of enteric origin. However, in more recent series, superinfection was found to haveoccurred in only upto 4% of cases8.Both amoebic and pyogenic abscesses can be single or multiple. Multiple pyogenic abscesses are moreapt to be caused by biliary tract disease whereas abscesses arising via the portal vein are usuallysolitary; the right lobe is more commonly involved than the left.Clinical differentiation of amoebic from a pyogenic liver abscess is based on the clinical presentationand recognition of epidemiologic risk factors, a lack of predisposing conditions for pyogenic liverabscess, and early use of noninvasive imaging studies. History of dysentery may not be available.Concomitant diarrhea occurs in 30 to 40% of patients; amoebae are found in stool by microscopicexamination even less frequently1. Although older studies emphasize that an amoebic liver abscesspresents as a single large lesion in the right lobe of the liver, studies using modern imaging technologydemonstrate a high frequency of multiple lesions9. Abscess may be aspirated if there is a high suspicionof pyogenic infection, in which case aspiration is both diagnostic and therapeutic.The differentiation of amoebic from a pyogenic liver abscess is greatly assisted by amoebic serology,since laboratory tests like liver function tests and stool microscopy are non-discriminatory, facilities forculture are lacking and the positivity rate of bacterial culture (aspirate, blood) is only around 50%. Forthis reason, the anti-amoebic antibodies, in significant titres, constitute the defmitive diagnostic test ofamoebic liver abscess. The antibodies are positive in up to 99% of patients with invasive amoebiasis1.Sensitivity of serology is generally quoted to be approx. 90% for amoebic liver abscess10. In a localstudy on 100 liver abscesses, the indirect haemagglutination test (IHA) was found to be 100% sensitiveand 94% specific for amoebic liver abscess11. The cut off point of antibody titre between normalpopulation and patients with invasive amoebiasis has been found to be 1:128 in an endemicpopulation”. Antibodies persist for a long time after resolution of infection, the titre and duration ofpersistence may not be influenced by early institution of specific chemotherapy12. Furthermore, IHAtest has been shown to remain positive for 20 years after infection13.Therefore, serologic tests for amoebiasis should be interpreted with caution. A physician practising inan endemic area must bear in mind the frequent occurrence of asymptomatic infection with pathogenicE. histolytica, which leads to the high prevalence (10-35% of population) of serum anti:amoebicantibodies10. Another possible pitfall in interpretation would be in patients with an acute presentationof less than 7 days, when serologic studies may be negative.Based on relevant clinical data, most cases of amoebic liver abscess can be diagnosed and treatedwithout aspiration. In some cases, antimicrobials directed against enteric gram negative organisms maybe added to metronidazole therapy, pending the results of serologic studies. Therapeutic trials ofspecific anti-amoebic therapy can be helpful diagnostically; most patients respond within 3 days withdecreased pain and fever, The liver abscess cavity usually resolves gradually over months but persistentcystic lesions are not unusual. Serial ultrasonography has shown that at 6 months after successfultreatment, only one-third to two-thirds of amoebic liver abscesses resolve completely10. Persistence ofcystic lesions, presence of E. histolytica cysts in stool in carriers and high titres of anti-amoebicantibodies in endemic population are some of the confounding factors, which should be kept in mind inthe work-up of a patient suspected to have liver abscess.References 1.Mandell GL, Bennett JE, Dolin R. Principles and Practice of Infectious Diseases. 5th ed. Edinburg:Churchill Livingstone, 2000, PP. 840-42.2.Barbour GL, Juniper K Jr. A clinical comparison of amoebic and pyogenic abscesses of the liver insixty-six patients. Am. J. Med., 1972;53:323-34.3.Ribaudo JM, Ochsner A. Intrahepatic abscesses: Amebic and pyogenic. Am. J. Surg., 1973; 125:570-74.4.Miedema BW, Dineen P. The diagnosis and treatment of pyogenic liver abscesses. Ann Surg., 1984;200:328-35.5.Shulman ST, Beem MO. A unique presentation of sickle cell disease: pyogenic hepatic abscess.Pediatrics, 1971; 47:1019-22.6.Kusne S, Dummer JS, Singh N, et al. Infections after liver transplantation: An analysis of 101consecutive cases. Medicine, Baltimore, 1988;67:132-43.7.Perera MR, Kirk A, Noone P. Presentation, diagnosis and management of liver abscess.Lancet,1980;2:629-32.8.Barnes PF, DeLock KM. Reynolds TN, et al. A comparison of amoebic and pyogenic abscess of theliver. Medicine (Baltimore). 1 987;66:472-83.9.Rails PW, Henley DS, Colletti PM, et al. Amoebic liver abscess: MRI imaging. Radiology,1987;165:801-4.10.Petri WA Jr., Singh U. Diagnosis and management of amoebiasis. Clin. Inf. Dis., 1 999;29: 1117-25.11.Khan MH, Qamar R, Shaikh Z. Serodiagnosis of amoebic liver abscess by IHA method. J. Pak.Med. Assoc., 1989;39:262-64.12.Knobloch J, Mannweiler E. Development and persistence of antibodies to Entamoeba bistolytica inpatients with amoebic liver abscess. Analysis of 216 cases. Am. J. Trop. Med. Hyg., 1983;4:727-32.13.Patterson M, Healy GR, Shabot JM. Serologic testing for amoebiasis. Gastroenterology, 1980;78:136-41.

Abscesses in the liver: amoebic or pyogenic?

https://ecommons.aku.edu/cgi/viewcontent.cgi?article=1477&amp;context=pakistan_fhs_mc_med_med

Abscesses in the liver: amoebic or pyogenic?

Abstract

Similar works

Full text

Available Versions

eCommons@AKU