Analysis of bacteria-derived extracellular vesicles in the urine of patients with sepsis

Background: Extracellular vesicles (EVs) are secreted by all bacteria, including those that cause sepsis, and are distributed throughout the bloodstream before getting excreted in the urine. The study aimed to analyze bacterialderived extracellular vesicles in the urine of patients with sepsis and compare them with those in healthy controls. Methods: The study included a total of 25 patients, comprising 9 cases with positive bacterial cultures in clinically significant specimens and 11 healthy controls. Urine samples, either midstream or collected via Foley catheter, were obtained before the initiation of antibiotic treatment. Extracellular vesicles were isolated from these samples using centrifugation. Metagenomic analysis was conducted on the isolated EV samples, focusing on bacterial 16S rDNA to identify the bacterial genera present. Results: In all febrile patients with culture-positive cases, genetic material from multiple bacterial genera was detected through metagenomic analysis, although the specific bacteria identified in clinical cultures were not found in most cases. The bacterial distributions observed in the normal control group were markedly different from those in the febrile patients. Conclusions: The findings suggest that bacterial components are likely entering the bloodstream from multiple sites within the body in the form of extracellular vesicles, both in septic and normal states. The distinct bacterial distributions observed in the urine of sepsis patients compared to healthy individuals require further investigation to understand the underlying mechanisms.