Spontaneous bacterial peritonitis (SBP) is defined as an ascitic fluid infection without an evident intra-abdominal surgically-treatable source . The presence of SBP, which almost always occurs in patients with cirrhosis and ascites, is suspected because of signs and symptoms, such as fever, abdominal pain, or altered mental status (table 1). (See "Spontaneous bacterial peritonitis in adults: Clinical manifestations".)
The diagnosis is established by a positive ascitic fluid bacterial culture and an ascitic fluid absolute polymorphonuclear leukocyte (PMN) count ≥250 cells/mm3. Patients with SBP should be started on empiric, broad-spectrum antibiotics immediately after peritoneal fluid is obtained. When culture results are available, antibiotic coverage can be tailored to cover the specific organisms identified. (See "Spontaneous bacterial peritonitis in adults: Diagnosis".)
This topic will review the treatment and prophylaxis of SBP. The performance of paracentesis, the pathogenesis, clinical manifestations, and diagnosis of SBP, and the general evaluation of adults with ascites are discussed elsewhere. (See "Diagnostic and therapeutic abdominal paracentesis" and "Pathogenesis of spontaneous bacterial peritonitis" and "Spontaneous bacterial peritonitis in adults: Clinical manifestations" and "Spontaneous bacterial peritonitis variants" and "Spontaneous bacterial peritonitis in adults: Diagnosis" and "Evaluation of adults with ascites".)
In 2013, the American Association for the Study of Liver Diseases (AASLD) updated its guideline on the management of adult patients with ascites due to cirrhosis (table 2) [2,3]. The discussion that follows is consistent with that guideline.
In patients with suspected spontaneous bacterial peritonitis (SBP), empiric therapy should be initiated as soon as possible to maximize the patient's chance of survival (algorithm 1 and table 2) [2,3]. However, antibiotics should not be given until ascitic fluid has been obtained for culture. Most cases of SBP are due to gut bacteria such as Escherichia coli and Klebsiella, though streptococcal and staphylococcal infections can also occur (table 3). As a result, broad-spectrum therapy is warranted until the results of susceptibility testing are available. We prefer cefotaxime 2 g intravenously every eight hours because it has been shown to produce excellent ascitic fluid levels. In addition to antibiotic therapy, patients with SBP who are taking a nonselective beta blocker should have the medication discontinued. (See "Spontaneous bacterial peritonitis in adults: Diagnosis", section on 'Obtaining ascitic fluid'.)