Spontaneous bacterial peritonitis: a prospective investigation in predominantly nonalcoholic cirrhotic patients.

Abstract

Two hundred and twenty-four consecutive inpatients with cirrhosis, mostly of nonalcoholic etiology, and ascites were prospectively investigated on admission for spontaneous bacterial peritonitis (SBP) by culture, smear, and polymorphonuclear (PMN) counts of ascitic fluid. Positive cultures were found in 54 patients. A possible intraabdominal source of infection was apparent in five of them, all with clinically overt peritonitis (secondary peritonitis). No intraabdominal source of infection was identified in the remaining 49. These patients were classified into the following groups: (a) SBP, 27 patients (positive cultures plus PMN counts ± 250 per mm3). Nine of them had no clinical features of peritonitis (silent SBP) in contrast to the other 18 (symptomatic SBP). (b) Bacteriascites (BA), 18 patients (positive culture with PMN counts less than 250 per mm3 in the absence of clinical peritonitis). Four patients were unclassified. Among 170 patients with negative culture, six had an overt peritonitis plus a positive smear and PMNs ± 250 per mm3 into ascites and were considered as probable SBP. The remaining 164 patients were classified as sterile ascites. A single strain of Gram-negative bacteria (usually of enteric origin) was recovered frequently in patients with symptomatic or silent SBP (79%) whereas Gram-positive bacteria were more frequently found in patients with BA (61%, p < 0.01). In-hospital mortality showed a statistically significant difference among patients with SBP (48%) and those with BA (22%) or sterile ascites (18%) (p < 0.05 and p < 0.0005, respectively). We conclude that SBP is frequent event in nonalcoholic cirrhosis. Bacterial contamination of ascites may remain in balance or progress to overt peritonitis according to the pathogenicity of the agent. SBP carries a high mortality in comparison to sterile ascites or BA despite early antibiotic treatment.