Bactericidal and opsonic activity of ascitic fluid from cirrhotic and noncirrhotic patients

Cirrhotic patients with ascites are highly susceptible to spontaneous bacterial peritonitis. Patients with ascites due to causes other than cirrhosis very seldom develop peritonitis. The antibacterial activity of these ascitic fluids is not known. The present study was undertaken to evaluate the bactericidal and opsonic activity in ascitic fluid from patients with and without cirrhosis and in normal (nonascitic) peritoneal fluid. Normal peritoneal fluids of 20 control subjects and ascitic fluids of 22 patients with noncirrhotic ascites all had normal bactericidal activity. The bactericidal activity of ascitic fluid was diminished in all 25 patients with cirrhosis (P less than 0.00005 by Fisher's exact test). Similar results were found when opsonic activity was evaluated. Complement and immunoglobulin concentrations in cirrhotic ascites were significantly lower than those in the other two groups. The present study demonstrates that noncirrhotic ascitic fluid has antibacterial activity similar to normal peritoneal fluid, whereas cirrhotic ascitic fluid has a marked reduction of both bactericidal and opsonic activities. These defects may explain the high incidence of peritonitis in cirrhotic patients.