Bacterial dissemination and the value of blood cultures in patients who die of septic shock.

The aim of this study was to determine whether blood cultures reflect real bacterial dissemination into the tissues of patients who die of septic shock. A total of 20 patients were divided into two groups with surgical (nine) and nonsurgical (11) sepsis. Blood cultures were taken and the adequacy of antibacterial therapy was assessed. Postmortem tissue samples of different organs were studied using light microscopy for the presence of bacteria. A semiquantitative measure, the contamination index, was applied. Despite negative blood cultures from 14 patients, bacteria were found in almost all of the organs examined from all of the patients. There was no difference in contamination index between patients who received adequate antibacterial therapy and those who did not. We conclude that septic shock is the manifestation of bacterial dissemination into the organs, and that blood cultures are of limited value in the diagnosis of sepsis, especially when they are taken during adequate antibacterial therapy.