Diuresis increases ascitic fluid opsonic activity in patients who survive spontaneous bacterial peritonitis.

Patients with low protein ascites and deficient ascitic fluid opsonic activity have been shown to be unusually predisposed to development of spontaneous bacterial peritonitis. Survivors of spontaneous peritonitis frequently develop recurrent infection. Diuresis has been shown to increase the ascitic fluid opsonic activity of patients who have never had spontaneous bacterial peritonitis. Patients with adequate opsonic activity are protected from ascitic fluid infection. Theoretically, the subset of patients who develop spontaneous peritonitis may have such severe liver disease that (i) their ascites is refractory to diuretic therapy or (ii) their ascitic fluid opsonic activity does not increase in response to diuresis. In this study, opsonic activity and concentrations of total protein and complement components were measured in the ascitic fluid of 11 patients who were hospitalized with spontaneous bacterial peritonitis and who responded to oral diuretics. The mean values of all of these parameters were found to increase significantly comparing the end-of-diuresis samples to the specimens that were diagnostic of ascitic fluid infection. Patients who survive spontaneous bacterial peritonitis are able to increase their ascitic fluid total protein and opsonic activity in response to diuresis. This increase in endogenous antimicrobial activity may help prevent recurrence of ascitic fluid infection.