Bacterial Dissemination and the Value of Blood Cultures in Patients Who Die of Septic Shock

Abstract

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.

Dissemination of Bacteria in Multiple Organs Associated with Apoptosis and Macrophage Activity in Different Stages of Experimental Sepsis

“…In the sites of obstruction or a very slow blood flow, deficiency of phagocytosis and uncontrolled growth of microbes may be present (17,18,19,20,21). Our findings of bacterial clusters in capillaries support this suggestion (11,12). The second wave of the multiplication of microbes proved our supposition that it must take hours of stasis in microcirculation to enable bacteria to multiply in this amount in tissues.…”

“…The vascular changes of different frequency such as hyperaemia, intestinal and perivascular oedema and stasis found in most of the organs by 24 th hour were accentuated in the lungs, liver and kidneys. More severe changes of a different expression -haemorrhages, thrombi, necrosis -prevailed in late sepsis (12,14). Vascular changes seem to be possible reasons which led to the obstruction of blood flow already during the first hours and, owing to that, to the destruction and necrosis of tissues.…”

“…The present experimental work has been evolved from our earlier clinical work concerning the septic shock with disseminated microfoci in multiple organs in humans done in the Intensive Care Unit of the Department of Anesthesiology and Intensive Care, University of Tartu. A number of questions were induced by the analysis of the patients who died of the septic shock despite adequate antibacterial therapy, and supportive measurements were assessed in protection against translocation (11,12). The aim of the study was to set up an experimental model of Gram-negative sepsis in rats, to detect the translocation of bacteria into different organs, to evaluate macrophage activity and a programmed cell death in the rats' liver during different stages of sepsis and to determine the correlation between these parameters.…”

Pseudomonas aeruginosa Potentiates the Lethal Effect of Intestinal Ischemia-Reperfusion Injury: The Role of In Vivo Virulence Activation

“…Depending on the virulence strategy and degree of subversion needed to survive, many accidental pathogens may completely elude clinical detection when they initiate and sustain the process of enteric driven inflammation (i.e. gut-derived sepsis) 3 .…”

“…), P. aeruginosa continues to be widely regarded as one of the most common microbes associated with lethal gut-derived sepsis. In one of the most cited publications describing the microbiology of the gut during surgical critical illness, P. aeruginosa was among the top 3 pathogens present in patients with sepsis syndrome and the only pathogen independently associated with a statistically significant increase in mortality 3 . This was recently confirmed in critically ill trauma patients ill where those whose feces cultured positive for P. aeruginosa had a high probability of developing SIRS 5 .…”