Bacterial infections complicating liver disease.

Bacterial infection is a serious and often fatal complication of patients with liver disease and can prove fatal either directly or by precipitation of gastrointestinal bleeding, renal failure, or hepatic encephalopathy. At greatest risk are patients with alcoholic cirrhosis or decompensated chronic liver disease, or cases of acute liver disease who progress to fulminant hepatic failure or subacute hepatic necrosis. Infection appears to be unusual in patients with primary biliary cirrhosis. The site and type of infection is unrelated to the aetiology of the liver disease. Bacteraemia, pneumonia, urinary tract infection and spontaneous bacterial peritonitis are most common but infective endocarditis and meningitis, especially with pneumococci, are easily overlooked. Clinical suspicion of infection must be high as the only indication may be a general deterioration in the patients' clinical state, increasing encephalopathy or renal impairment. In the case of patients with fulminant hepatic failure, infection may precipitate the initial or recurrent encephalopathy and contributes to death in 10% of fatal cases. Spontaneous bacterial peritonitis is now recognized to occur in the absence of clinical features of peritonitis. The PMN content of the ascitic fluid may provide the only indication of infection and is the most readily available screening test. The most common types of organism responsible for all types of infection are Gram-negative enteric and streptococci, especially pneumococci, while infection with anaerobes is rare. Risk factors for infection include decompensated alcoholic liver disease, fulminant hepatic failure, gastrointestinal bleeding, invasive practical procedures and impaired host defence mechanisms against infection. Of the host defence mechanisms, impaired function of the reticuloendothelial system, complement, and PMNs represent the most common and serious defects. Defects of humoral immunity are present in ascitic fluid from patients with cirrhosis and are probably a major reason for development of spontaneous bacterial peritonitis. Diuresis improves these functions and reduces the risk of peritonitis. Treatment of infections even with the appropriate antibiotic is still associated with a high mortality but the use of adjuvant gut sterilization is promising, particularly in cases infected with Gram-negative enteric organisms. Infusions of fresh frozen plasma, blood and cryoprecipitate improve some systemic host defences and may be beneficial in the treatment and reduction of risk of infection.