%0 Journal Article %T Diagnosis of Spontaneous Bacterial Peritonitis and an In Situ Hybridization Approach to Detect an ˇ°Unidentifiedˇ± Pathogen %A Hirayuki Enomoto %A Shin-ichi Inoue %A Akio Matsuhisa %A Shuhei Nishiguchi %J International Journal of Hepatology %D 2014 %I Hindawi Publishing Corporation %R 10.1155/2014/634617 %X Spontaneous bacterial peritonitis (SBP) is a frequent and severe complication in cirrhotic patients with ascites. Although identifying the pathogen(s) plays a major role in the management of infectious diseases, ascitic fluid cultures often show negative results in patients with clinical signs and symptoms of SBP, and ascitic fluid cell analyses are the gold standard method for diagnosing SBP. SBP is generally diagnosed based on an increased number of polymorphonuclear neutrophils in the ascitic fluid ( 250/mm3), and the identification of the causal pathogen may not be given consideration. We newly developed an in situ hybridization (ISH) method to provide early and direct evidence of bacterial infection in ascites in patients with SBP. This paper will review the diagnosis of SBP, including our novel approach with ISH method to detect bacterial DNA in SBP ascitic fluid. 1. Introduction Spontaneous bacterial peritonitis (SBP) is a frequent and severe complication in patients with cirrhosis and ascites. SBP is a bacterial infection that occurs in the absence of an evident intra-abdominal and surgically treatable source of infection, such as the perforation or inflammation of intra-abdominal organs [1¨C4]. Although the precise mechanism(s) underlying the development of SBP have not been fully clarified, bacterial translocation (BT) is believed to be the most important causative factor. Mild BT to the mesenteric lymph nodes is a documented physiological event; however, only a few intestinal bacteria, including Escherichia coli, Klebsiella pneumoniae, and other Enterobacteriaceae, are able to efficiently translocate from the lumen of the gut to the mesenteric lymph nodes [5, 6]. Since the bacterial species with a capacity for BT are also major pathogens of SBP, unphysiological disease-related BT is thought to be significantly associated with the development of SBP. In addition, several conditions frequently noted in cirrhotic patients, including alterations in gut flora, increased intestinal permeability, and a compromised immune system, have been reported to be involved in disease-related BT and the subsequent onset of SBP [6]. The prevalence of SBP in cirrhotic hospitalized patients with ascites ranges from 10% to 30% [1, 2, 7]. Although the mortality rate was initially reported to exceed 90%, the prognosis has improved with early diagnosis and treatment [8]. The diagnosis of SBP is established based on positive ascitic fluid bacterial cultures and the detection of an elevated absolute fluid polymorphonuclear neutrophil (PMN) count in the ascites (>250/mm3) %U http://www.hindawi.com/journals/ijh/2014/634617/