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 shoc k. A total of 20 patients were divided into two groups with surgical (nine) and non-surgical (11) sepsis. Blood cultures were taken and the adequacy o f antibacterial therapy was assessed. Post-mortem tissue samples of differe nt 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 i n contamination index between patients who received adequate antibacterial therapy and those who did not. We conclude that septic shock is the manifes tation of bacterial dissemination into the organs, and that blood cultures are of limited value in the diagnosis of sepsis, especially when they are t aken during adequate antibacterial therapy.