The early increase in intestinal permeability and systemic endotoxin exposure in patients with severe acute pancreatitis is not associated with systemic bacterial translocation: Molecular investigation of microbial DNA in the blood

Introduction: Sepsis is the main cause of late mortality in patients with severe acute pancreatitis and is largely attributed to secondary infection of pancreatic necrosis with gram-negative enteric organisms. This is commonly preceded by a significant increase in intestinal colonization with such microbes and with early increases in intestinal permeability, thus suggesting a mechanism of local bacterial translocation. Whilst cultures of blood specimens from these patients often remain sterile, it is conceivable that bacteria might translocate systemically in small volumes with detrimental effects but elude detection by standard microbial culture techniques. Aims: To investigate the incidence and frequency with which bacterial DNA may exist in the systemic circulation of patients with acute pancreatitis and to relate that to disease severity, changes in intestinal permeability, and systemic endotoxin exposure. Methodology: Blood samples were obtained at admission and on days 3 and 7 from 26 patients with acute pancreatitis (seven with severe cases) and from 10 healthy controls for DNA extraction and standard microbial cultures. Polymerase chain reaction techniques were used to amplify a gene region (16S ribosomal RNA) found in all bacteria. Levels of serum endotoxin and antibodies to endotoxin core (EndoCAb) were measured at admission, and intestinal permeability to the macromolecule polyethylene glycol 3350 was determined within 72 hours of the onset of symptoms. Results: Blood cultures yielded Escherichia coli and enterococci for one patient with a severe attack and coagulase-negative staphylococci for another patient with a mild attack. No bacterial DNA was found in any of the samples. Endotoxemia was detected in 20 patients (five with severe cases), and levels of serum IgM EndoCAb were depleted in patients with severe attacks but remained relatively unchanged during mild attacks (p=0.033). Intestinal permeability was significantly increased in patients with severe attacks of acute pancreatitis but remained unchanged during mild attacks (p<0.05). Conclusions: Whilst severe attacks of acute pancreatitis are associated with early derangement in gut barrier function and systemic endotoxin translocation, there is no molecular evidence for associated systemic bacterial "translocation."