Bacterial DNA (bactDNA) is present in blood and ascitic fluid (AF) in a third of patients with cirrhosis and ascites, but whether this phenomenon represents episodes of bacterial translocation (BT), strictly considered when culture of mesenteric lymph nodes (MLNs) are positive, remains unknown. This study assessed the relationship between bactDNA detection in biological fluids and MLNs and went on to investigate the local and systemic inflammatory status according to its presence. Cirrhosis was induced in rats by ingestion of CCL 4 . A subgroup of five animals with cirrhosis received norfloxacin (5 mg/kg/day) for 7 days. MLNs and ascitic and pleural fluids were collected at laparotomy and cultured; samples were collected for identification of bactDNA and measurement of tumor necrosis factor-alpha (TNF-␣), interleukin-6 (IL-6), and nitric oxide (NO). BactDNA was detected in MLNs in 12 of 19 animals (63.1%), corresponding in seven cases to culture-positive MLNs, and in five to culture-negative MLNs. BactDNA was detected in biological fluids in 11 of 19 animals (57.9%), and in all cases the same bacteria spp. detected in samples was present in MLNs. BactDNA was not detected in any biological sample from animals receiving norfloxacin. Tumor necrosis factor alpha (TNF-␣), IL-6, and NO were similar in culture-positive and culture-negative/bactDNA-positive samples, and significantly higher than those observed in animals with culture-negative/bactDNA-negative MLNs, animals with cirrhosis that were receiving norfloxacin, and controls. In conclusion, the presence of bactDNA in biological fluids in rats with cirrhosis constitutes a marker of BT, and it is associated with a marked inflammatory response, independent of the result of the culture. (HEPATOLOGY 2006;44:633-639.)
B acterial translocation (BT) is considered a key event in the pathogenesis of bacterial infections in patients with advanced cirrhosis, 1 and spontaneous bacterial peritonitis is probably the most relevant in-fection in this setting. 2 BT is considered to be present either in patients or in animal models of cirrhosis when the culture of mesenteric lymph nodes (MLN) shows the growth of at least one bacterial species. 3 The genetic identity of bacteria isolated in ileal content, MLNs, and infected ascitic fluid (AF) in rats with experimental cirrhosis 4 has been shown, which supports the contention of a continuum among intestinal lumen, translocation to MLN, and eventual induction of spontaneous bacterial peritonitis. However, the study of BT is logically difficult in patients with cirrhosis.
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-