Amebic Liver Abscess

What is Amebic Liver Abscess?

Amoebic liver abscess is a purulent inflammation of the liver tissue as a result of the necrotizing action of the dysenteric amoeba brought by the portal blood flow from the large intestine.

Amoebic liver abscess is a complication of acute or recurrent intestinal amebiasis. Amoebic abscesses occur mainly in middle age, more often in men. Amebic abscess is usually single, large, located more often in the right lobe. The contents of the abscess are liquid, of a characteristic red-brown color (the so-called anchovy paste).

Causes of Amebic Liver Abscess

The pathogenic agent is Entamaeba histolytica. There are three forms of liver damage to enameba: cyst as a stable form, a weakly pathogenic regressive form, and a histolytic form that causes both dysentery and liver abscess.

Pathogenesis during Amebic liver abscess

Parasitic (amoebic) abscesses are caused by the penetration of the simplest microorganisms into the liver tissue. Human infection occurs enterally. Amoebas are introduced into the submucosal layer of the small intestine, from where they later migrate to the venous vessels of the portal system. With blood flow, they reach the liver, where they cause necrosis of a limited area of ​​tissue, followed by its melting and the formation of solitary or (more rarely) multiple abscesses.

The amoeba that has entered the liver causes necrosis of the restricted area of ​​the liver tissue, then the latter disintegrates with the formation of a cavity in which the presence of the parasite can be detected. Over time, the abscess can self-sterilize, then the contents of the cavity have the consistency of chocolate-colored mastic. Up to 40% of amebic abscesses are infected with E. coli, then the contents become yellow-green and have a fecal odor.

It must be emphasized that in some patients microbial flora are sown from the contents of the parasitic abscess (most often colibacillary), while amoebas are found in the contents of the abscess only in individual patients. Most often, parasites are detected in the wall of the abscess.

The frequency of liver amebic abscesses in intestinal amoebiasis varies widely – from 1 to 25%. The disease usually occurs in people aged 20–40 years; men suffer 5–7 times more often than women.

Symptoms of Amebic Liver Abscess

The clinical picture of amebic liver abscess is almost similar to pyogenic abscesses, but the temperature is usually somewhat lower than with pyogenic abscesses, until a secondary infection joins. There is usually a history of past dysentery.

The clinic of amoebic liver abscess develops against the background of dysenteric bowel disease, in some cases it is masked. Amoebic abscess may occur not immediately, but after a few months or even years after bowel damage.

Amoebic liver abscess is acute and chronic.

Although the clinical picture of liver amebiasis differs by polymorphism, the most common typical symptoms are fever, abdominal pain and hepatomegaly.

The acute form is characterized by high (sometimes hectic) temperature, accompanied by chills, severe weakness, and profuse sweating.

In chronic form, body temperature is subfebrile, the disease proceeds without chills and sweating.

Pain is the earliest symptom. Initially, there is a feeling of heaviness in the abdomen, turning into a sharp pain, which decreases with a change in posture. With the defeat of the right lobe of the liver, pain is noted in the upper right abdomen and radiates to the right shoulder, neck and back. With an abscess in the left lobe, the pain is localized in the epigastric region and the upper left half of the abdomen, radiating to the back and left shoulder blade.

Hepatomegaly in liver amebiasis is the most important diagnostic sign. Depending on the location and size of the abscess, the nature of the liver enlargement is different. An increase in the whole organ, an increase in the right or left lobe, an increase in the lower and upper direction, which causes compression of the diaphragm, is possible. In such a situation, breathing is difficult. In case of large-sized abscesses, a bulging in the right hypochondrium or in the epigastric region is noticed, the abscess of the left lobe is detected by palpation.

In addition to these most common symptoms, jaundice (54%), vomiting (43%), diarrhea (35%), weight loss (30%), etc. are noted.

Possible complications of amebic liver abscesses.
Complications of amoebic abscesses of the liver are similar to those of pyogenic. The breakthrough of an abscess into the pleural cavity leads to the development of amoebic pleural empyema, into the lung tissue – to the formation of an abscess of the lung or bronchopleural fistula. Pericardial lesion occurs in 1-2% of patients and is associated with amebic abscesses located in the left lobe of the liver. Serous effusion in the pericardial cavity may indicate a threatening abscess breakthrough. The result of purulent amebic pericarditis often becomes compressive pericarditis. There are also reports of the development of brain abscesses in a patient with amebic liver abscesses as a result of hematogenous dissemination of the pathogen.

Diagnosis of Amebic Liver Abscess

The best methods for the differential diagnosis of amebic and pyogenic liver abscesses are serological tests, namely:

  • hemagglutination reaction (DA);
  • the reaction of indirect immunofluorescence (RNIF);
  • countercurrent immunoelectrophoresis (PIEF);
  • immunoelectrophoresis (IEF);
  • gel precipitation reaction (RPG);
  • complement fixation reaction (RAC);
  • latex agglutination reaction (RLA);
  • enzyme-linked immunosorbent assay (ELISA).

Positive results of serological tests are possible only in patients with invasive amebiasis (for example, with amoebic abscesses of the liver or amoebic colitis). In asymptomatic carriers, these reactions are negative. All tests, with the exception of RSK, have high sensitivity (up to 95-99%). The highest sensitivity is characteristic of DA; a negative result eliminates the diagnosis of amoebic lesions; in patients with invasive amebiasis, the titer is almost always> 1: 512. In addition, the DSA remains positive for several years and may indicate a previous infection. RPG becomes negative 6 months after the disease; This serological reaction is most preferable for the examination of patients arriving from endemic regions and with amebiasis in history. If a patient with a liver abscess reveals high titers in RPGs, this makes it possible to diagnose amoebic abscess (even if the patient has already had amoebiasis in the past). The choice of serological tests for the diagnosis of amoebic abscesses of the liver is determined by their availability and epidemiological situation.

Treatment of Amebic Liver Abscess

Surgical treatment of amoebic liver abscess is not indicated until the intestinal phase of the disease is eliminated.

Metronidazole 30 mg / kg 3 times a day for 10 days, then 10 days give it a half dose. At the same time, rezokhin is prescribed for 2 days, 2-3 g per day, then for 3 weeks 0.5 g 1 time per day, followed by treatment with tetracycline.

However, even in such a dose, metronidazole may not be sufficiently effective. In this case, the patient is prescribed an amebocide preparation acting in the intestinal lumen, for example, iodoquinol (diiodo-hydroxyquin), 650 mg 3 times a day for 20 days, which will allow to cure the intestinal infection and prevent the recurrence of the disease.

If, despite treatment with amebicides, the clinical or radiological picture of liver asbestos persists, its puncture is indicated, and if there is insufficient drainage and signs of secondary infection appear, external drainage is shown.

Forecast. Mortality in amebic abscess is 6-17%; it is caused by the development of complications – a breakthrough into the free abdominal or pleural cavity, pericardium, etc.

Prevention of Liver Amebic Abscess

Measures for the prevention of amebiasis are aimed at identifying infected with histolytic amoeba among risk groups, their rehabilitation or treatment, as well as to break the transmission mechanism.

Risk groups for amebiasis infection include patients with gastrointestinal pathology, residents of non-canalized settlements, employees of food enterprises and food trade, greenhouses, greenhouses, sewage treatment plants, people returning from amebiasis-endemic countries, homosexuals.

Persons entering work for food and similar enterprises (child care centers, sanatoriums, water supply facilities, etc.) are subject to a scatological (for helminth eggs and intestinal protozoa) examination. At revealing of a dysenteric amoeba they are subjected to sanitation. Among the risk groups, planned protozoological studies are carried out once a year by parasitological laboratories of territorial sanitary and epidemiological stations. Patients with acute and chronic intestinal diseases are protozoologically examined by the clinical and diagnostic laboratories of the relevant medical institution.

Dispensary observation of the patients is carried out for 12 months. Medical observation and laboratory tests are carried out once a quarter, as well as with the appearance of intestinal dysfunctions. Employees of food and equivalent institutions, infested with dysenteric amoeba are kept at the dispensary until complete sanation from the amebiasis pathogen.

Measures aimed at breaking the transmission mechanism include the protection of environmental objects from contamination with invasive material through sewage of populated areas, providing the population with good-quality drinking water and food, disinfecting items exposed to contamination from the patient’s discharges in treatment-and-prophylactic and other institutions means and boiling. An important place in the prevention of amebiasis belongs sanitary and educational work.

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