Detection and identification of bacterial DNA in patients with cirrhosis and culture-negative, nonneutrocytic ascites

Abstract

The current pathogenic theory of spontaneous bacterial peritonitis (SBP) in patients with cirrhosis and ascites suggests that repeated episodes of bacterial translocation (BT) from intestinal lumen to mesenteric lymph nodes followed by systemic seeding are the key steps for the final development of infectious events. However, most of the episodes of systemic bacterial circulation remain undetected. Therefore, we investigated the hypothetical presence of bacteria in blood and/or ascitic fluid (AF) from patients with cirrhosis and sterile (culture negative) AF by means of bacterial DNA (bactDNA) detection and identification. Twenty-eight consecutively admitted patients with cirrhosis and presence of AF were included in the study. BactDNA was detected using a polymerase chain reaction (PCR)-based method. The corresponding bacteria were identified by nucleotide sequencing of purified PCR products. BactDNA was detected simultaneously in blood and AF in 9 patients (32.1%). DNA sequencing allowed the identification of Escherichia coli (n ‫؍‬ 7) and Staphylococcus aureus (n ‫؍‬ 2). In all cases, the similarity between the sequence found in AF and blood indicated that the bactDNA present in both locations originated from a single clone (single translocation event). Child-Pugh score and basic hemodynamic, clinical, endoscopic, and biochemical characteristics were similar among patients with or without the presence of bactDNA. In conclusion, we have detected bactDNA in serum and AF in 32% of all patients studied, and this likely represents single clone episodes of translocation and systemic seeding. E. coli is the most frequently identified bacteria. (HEPATOLOGY 2002;36:135-141.)

Neutrophil dysfunction in alcoholic hepatitis superimposed on cirrhosis is reversible and predicts the outcome

“…It has been shown that 32% of patients with cirrhosis with culture-negative ascites have detectable bacterial DNA in the blood, which may indicate systemic bacterial seeding. 31 An important observation made through ex vivo experiments in this study was the demonstration that the neutrophil functional defect could be transmitted to normal neutrophils incubated with patients' serum. We also showed that the neutrophil dysfunction in the patients was reversible following incubation with normal serum.…”

Characterisation of bacteria in ascites—reporting the potential of culture-independent, molecular analysis

“…The inadequacy of culture-based assays to provide sufficiently rapid, accurate and comprehensive data on which to base clinical decisions has led to the development and use of culture-independent, molecular strategies in an increasing number of clinical contexts. The rationale for taking a culture-independent approach in this study was underpinned by earlier studies that have shown bacterial DNA in fluid from approximately 40% of cirrhosis patients with culture-negative, non-neutrocytic ascites [23,24]. Moreover, the presence of bacterial DNA has recently been shown to be associated with an increased risk of developing SBP [25].…”

The detection of bacterial DNA in blood of rats with CCl4-induced cirrhosis with ascites represents episodes of bacterial translocation

“…We have shown that roughly 30% of patients with advanced cirrhosis and AF show the simultaneous presence in blood and AF of fragments of bacterial DNA (bactDNA), mostly from the same type of bacteria, 5 and that these fragments may last in blood during variable periods. 6 The identity of the nucleotide sequences detected in a given patient during the study period, together with the fact that bactDNA may disappear and then re-appear in consecutive serum specimens, lead us to consider that the main mechanism promoting the presence of bactDNA in blood was repeated episodes of bacterial movement through the intestinal wall, and not a clearance defect.…”