Spontaneous bacterial peritonitis in patients with ventriculoperitoneal shunts

Spontaneous bacterial peritonitis (SBP) is an infection of the peritoneal fluid in the absence of an obvious intra-abdominal source. It is most commonly diagnosed in patients with cirrhotic ascites, although it has been described in other syndromes as well. The organisms most frequently cultured from the peritoneum are those of intestinal flora; however, there are cases which have all the features of SBP, but remain culture negative. This article discusses 7 cases of SBP in patients with ventriculoperitoneal shunts; a combination which has previously not been described. The most significant features of these cases include: a remote history of shunt revision (mean 3.4 years), and cultures consistent with normal intestinal flora. None had a history of recent abdominal surgery, gastrostomy or wire-impregnated catheters. Cerebrospinal fluid cultures are often negative, and when positive, suggest SBP with an ascending shunt infection. While SBP is clearly differentiated from pseudocyst of the abdomen, it may represent a point on the continuum of intra-abdominal processes in the shunted patient. The precise etiology of SBP is unclear. A number of suggested theories are reviewed. It is proposed that patients with shunts may be predisposed to develop SBP because spinal fluid can behave as an ascitic fluid even in the absence of a peritoneal accumulation. Recommendations for the recognition and management of SBP in the shunted patient are discussed in detail.