Spontaneous bacterial peritonitis (SBP) is infection of ascitic fluid without an apparent source. Manifestations may include fever, malaise, and symptoms of ascites and worsening hepatic failure. Diagnosis is by examination of ascitic fluid. Treatment is with cefotaxime or another antibiotic.
(See also Ascites.)
SBP is particularly common in ascites caused by hepatic cirrhosis. This infection can cause serious sequelae or death. The most common bacteria causing SBP are gram-negative Escherichia coli and Klebsiella pneumoniae and gram-positive Streptococcus pneumoniae; usually only a single organism is involved.
Symptoms and Signs of SBP
Patients have symptoms and signs of ascites. Discomfort is usually present; it typically is diffuse, constant, and mild to moderate in severity.
Signs of SBP may include fever, malaise, encephalopathy, worsening hepatic failure, and unexplained clinical deterioration. Peritoneal signs (eg, abdominal tenderness and rebound) are present but may be somewhat diminished by the presence of ascitic fluid.
Diagnosis of SBP
Diagnostic paracentesis
Clinical diagnosis of SBP can be difficult; diagnosis requires a high index of suspicion and liberal use of diagnostic paracentesis, including culture. Transferring ascitic fluid to blood culture media before incubation increases the sensitivity of culture to almost 70%. Polymorphonuclear leukocyte (PMN) count of > 250 cells/mcL (0.25 × 109/L) is diagnostic of SBP. The PMN count is the total number of white blood cells in the ascites by the percentage of neutrophils. Blood cultures are also indicated. Because SBP usually results from a single organism, finding mixed flora on culture suggests a perforated abdominal viscus or contaminated specimen.
Treatment of SBP
Cefotaxime or another antibiotic
Albumin for prevention of hepatorenal syndrome
If SBP is diagnosed, an antibiotic such as ceftriaxone or cefotaxime 2 g IV every 4 to 8 hours (pending Gram stain and culture results) is given for at least 5 days and until ascitic fluid shows < 250 PMNs/mcL. Antibiotics increase the chance of survival. Because SBP recurs within a year in up to 70% of patients, prophylactic antibiotics are indicated; quinolones (eg, norfloxacin 400 mg orally once/day) are most widely used.
Patients with SBP should receive 1.5 grams/kg of albumin (25%) on day 1 and 1 gm/kg on day 3 to reduce the risk of hepatorenal syndrome.
Antibiotic prophylaxis in ascitic patients with variceal hemorrhage decreases the risk of SBP.