Microbial DNA detection by nested-PCR in clinical samples from undiagnosed infections

Bacterial infections, such as spontaneous bacterial peritonitis, are frequent in patients with liver cirrhosis and ascites also due to facilitated translocation (bacterial translocation, BT) of intestinal microbes: bacteria escape from the intestinal lumen reaching the mesenteric lymphonodes and spreading into the bloodstream and the ascitic fluid (AF). Frequently patients are asymptomatic or show infection signs in the absence of positivity to standard diagnostic microbiological tests (culture method). In this study, various ascitic fluid samples collected from patients with severe liver pathology, were analyzed using PCR and nested-PCR targeting 16S ribosomal gene (universal bacterial primers)and entB primers (specific for identification of Enterobatteriaceae). The presence of bactDNA was revealed in 6 out 29 samples. In some of these specimens the results obtained by PCR was corroborated by the evidence of presence of bacterial molecules (PG and/or endotoxin) The role of the DNA and other bacterial markers (PG, endotoxin) in the AF of patients with severe liver diseases has still to be established although its presence in biological fluids seems to be an indirect index of bacterial translocation and a possible factor favouring infections.