Pyogenic Liver Abscess - Causes, Symptoms, and Treatment

Introduction:

Bacterial liver abscess is otherwise known as pyogenic liver abscess. The term pyogenic refers to the formation of pus. The bacterial infection may cause pus formation in the liver. One or more bacteria are involved in most cases. Pus is the fluid consisting of white blood cells and dead cells formed when the body fights against infection. An abscess may cause swelling and inflammation of the surrounding area.

What Is a Pyogenic Liver Abscess?

A pyogenic liver abscess refers to the pus pocket formed within the liver due to bacterial infection. In the case of a pyogenic liver abscess, the drainage of pus does not occur, and it gets collected in a pocket in the liver and results in the formation of an abscess. A pyogenic liver abscess causes severe pain and swelling in the abdomen. If the abscess is not treated properly, it may result in a life-threatening condition.

What Are the Causes of Pyogenic Liver Abscess?

• Polymicrobial involvement is most commonly seen. The two most commonly encountered bacterial species include Klebsiella pneumoniae and Escherichia coli.

• Reports suggest that Klebsiella pneumoniae is involved in most cases.

• The abscess caused by Klebsiella pneumoniae is mostly associated with endophthalmitis, whereas abscesses involving Escherichia coli are mostly associated with biliary infection.

• Staphylococcus aureus abscess occurs as a result of distant infections, such as endocarditis, in which the organisms are spread hematogenously.

• An infection through bacterial anaerobes accounts for about 45 % of cases.

• The frequently isolated anaerobic pathogens include Fusobacterium species, Bacteroides species, and microaerophilic and anaerobic streptococci.

• Staphylococcus milleri is also responsible for causing monomicrobial or polymicrobial abscesses in patients with pyogenic liver abscesses.

Other causes:

• Any trauma or injury that affects the liver.

• Infection of the bile draining tubes.

• Recent endoscopy of bile tubes.

• Infection that occurs in the blood.

• In case of an abdominal infection, such as diverticulitis, perforated bowel disease, or appendicitis, a pyogenic liver abscess can occur.

What Are the Symptoms of Pyogenic Liver Abscess?

The most common symptoms of a pyogenic liver abscess include:

• Fever.

• Chills.

• Night sweats.

• Nausea.

• Vomiting.

• Loss of appetite.

• Weight loss (unintentional).

• Jaundice.

• Right shoulder pain (referred pain).

• Weakness.

• Loss of appetite.

• Dark-colored urine.

• Chest pain in the lower right region.

• Clay-colored stools.

• Pain in the right upper abdomen or throughout the abdomen.

What Are the Investigatory Approaches to Pyogenic Liver Abscess?

• Imaging Studies - Imaging studies are in the diagnosis of hepatic abscesses.

• Abdominal X-Rays - Reveals the presence of gas within the abscess cavity (10 to 20 %) and elevation of the diaphragm.

• Radioisotope Scanning - It is one of the most common methods used for a longer period.

• Ultrasonography - It is one of the most preferred methods in the initial diagnosis. An accuracy rate of 80 to 90 % is observed in the diagnosis of intrahepatic abscesses. The findings of ultrasonography reveal hypoechoic lesions and irregular margins. The presence of microbubbles or hyperechoic spots with reverberations confirms the presence of gas within the cavity. The ultrasonography findings help in differentiating the pyogenic and amebic abscesses.

• Computerized Tomography - Computerized tomography findings reveal the intrahepatic collections as small as 0.5 centimeters. This test may show well-defined round or oval cavities and lobulations with poorly marginated edges. A needle aspiration technique done along with ultrasonography and computerized tomography has a significant role in the easy diagnosis of liver lesions. The gram stain analysis of the aspirate reveals the presence of the bacteria and polymorphonuclear leukocytes in the pyogenic abscess.

• Magnetic Resonance Imaging - It is one of the most accurate and sensitive methods for the identification of liver diseases. The accuracy is more when magnetic resonance imaging is done with Gadolinium - BOPTA.

What Are the Treatment Approaches for Pyogenic Liver Abscess?

The treatment options vary individually and are decided based on the requirement and the patient’s underlying clinical condition. In the case of pyogenic liver abscess, both antibiotic therapy and proper drainage are important for better management. Proper drainage is attained through open conventional methods or laparoscopic or surgical approaches.

Antibiotic Therapy: It should include drugs that are effective against all the common microorganisms obtained in the liver abscess aspirate culture. It should be started as early as possible, depending on the culture of organisms obtained from the aspiration. Wide-spectrum antibiotics are effective in the treatment of a pyogenic liver abscess. The best combination of antibiotics used in the treatment of pyogenic liver abscess include:

• Aminoglycosides with Clindamycin or Metronidazole.

• Beta-lactam antibiotics with anaerobic coverage.

Penicillinase-resistant Penicillin or first-generation Cephalosporins are used to treat infections involving Streptococcus and Staphylococcus species. In the case of biliary disease, antibiotic combination therapy consists of Ampicillin with an aminoglycoside or Ureidopenicillin with aminoglycosides. The main criteria for antibiotic therapy include the following:

• The infected patient should be in good clinical condition.

• The size of the abscess should be smaller than two centimeters in diameter.

The duration of the antibiotic therapy depends on the clinical response and the number of abscess sites. Antibiotic therapy should be given for about four to six weeks in the case of multiple abscesses.

Drainage: Drainage of the pus is an important and effective way to treat abscesses. This can be performed either surgically or percutaneously, guided by ultrasound or computed tomography. The factors considered before choosing the drainage therapy include the following-

• The success rate.

• Presence or absence of any associated intra-abdominal pathology.

• Anesthetic risk of the patient.

• The expertise involved in managing the conditions.

Surgical Management: The surgical approach for a pyogenic liver abscess is determined based on the source of the abscess and the patient's underlying clinical condition. The primary aim in approaching surgically includes source control. The source of infection is completely eliminated by performing laparotomy and surgical drainage. The location is very significant in determining surgical management. An abscess situated in the dome of the liver is approached between the tenth and eleventh ribs transpleural.

This approach can avoid peritoneal contamination, but the limited exposure is the disadvantage. Nevertheless, it accounts for about 91.5 % of the success rate, which works well in sepsis patients to prevent a high risk of mortality and morbidity rates. Intraoperative ultrasonography helps in locating the abscess during the procedure.

Conclusion:

Pyogenic liver abscess is uncommon but possesses serious complications. A timely diagnosis and proper treatment help better management of the condition. An interprofessional team approach should be made to manage well and bring out positive patient outcomes.