Spontaneous Salmonella infection of high-protein noncirrhotic ascites

Spontaneous bacterial peritonitis rarely complicates high-protein (greater than 2.5 g/dl) ascites. The relatively high endogenous antimicrobial (opsonic) activity of the ascitic fluid in this setting appears to protect the patient from infection. We report two patients with high-protein, noncirrhotic ascites complicated by spontaneous peritonitis due to Salmonella species. One patient had ascites due to heart failure, whereas the other patient's ascites was due to peritoneal carcinomatosis. The ascitic fluid total protein concentrations were 3.1 and 3.3 g/dl, respectively, and the opsonic activity of the ascitic fluid specimens were 2.03 and 2.00 log kill, respectively, indicating a high degree of bacterial killing. We hypothesize that the virulence of the Salmonella species was able to overcome the high opsonic activity in the ascitic fluid, resulting in infection in these two patients. Fever, abdominal pain, or encephalopathy in a patient with high-protein ascites may suggest the presence of an unusual organism causing spontaneous bacterial peritonitis.