Pyogenic liver abscess

Discussion today surrounded an atypical presentation of a pyogenic liver abscess. Typically, this condition will present with fever, sweats, abdominal pain (usually RUQ) and occasionally symptoms of systemic infection. Todays case was a bit strange, given the only consistent features were constitutional symptoms, and atypical chest and abdominal pain were misleading. As a result, one must have a high index of suspicion for a liver abscess with fever of unknown origin (FUO). Following negative preliminary testing in the evaluation of FUO abdominal imaging should be considered, especially when there are abnormal liver enzymes. This approach led to a diagnosis in 19% of cases where first line tests were unrevealing.

Pyogenic liver abscess is the most common visceral location for focal infection. That being said, its really not that common, where some studies quote 2-3 cases per 100,000. Most studies on epidemiology of liver abscess have been performed in South East Asia, and may even be more uncommon in our population.

These infections can develop through several mechanisms:

1. Hematologic bacteremia leading to seeding
2. Biliary obstruction and reflux of bacteria into liver parenchyma
3. Direct invasion through adjacent structures (gastric perforation) or contact through bowel leakage/perforation

Most often these infections involve the right side of the liver given the blood supply tends to be larger for this lobe.

Many micro-organisms can cause liver abscess formation. Some of these include:

Strep. anginosis, staph. aureus and strep pyogenes are amongst the most common pathogens involved. Klebsiella sp., as in our patient, which is a gram negative abscess forming bacteria is also well described. There was a large case series from Taiwan which found that Klebsiella was a common cause of liver abscess (nearly 70%), most often developed in the community, and was associated with DMII and hyperglycemia.

The treatment of these patients is antibiotic therapy, with a strong focus on source control. Abscess drainage can be both therapeutic and diagnostic and is a required part of therapy unless the abscess are too small for drainage. Antibiotic therapy should be targeted towards the identified infection, and duration consist of at least 4 weeks of IV antimicrobials.

One case series of Klebsiella liver abscess patients found an overall mortality rate of nearly 10%, and a relapse rate of 4%. Sepsis was the cause of death in all of those who died. This organism can be aggressive and patients should be evaluated for additional metastatic sites of infection.