Central Nervous System and the Colonic Bioreactor: Analysis of Colonic Microbiota in Patients with Stroke Unravels Unknown Mechanisms of the Host Defense after Brain Injury

Background/Aims: Stroke is accompanied by septic complications due to quickly changing polymicrobials of unclear origin. This study was aimed to find the source of stroke-associated-infections. Methods: We investigated the biostructure of the colonic microbiota in patients hospitalized in two stroke units using fluorescence in situ hybridization in order to find the source of stroke-associated-infections. Non-stroke subjects and animals were used as controls. Results: Typical for stroke was a leukocyte migration into the mucus between day 1-3, in numbers that are otherwise characteristic for active ulcerative colitis (CAI >= 6); subsequent abrupt decontamination of the main fermentative Roseburia, Bacteroides and Faecalibacterium prausnitzii groups and disappearance of leukocytes in the stool; arrest of bacterial fermentation between day 3 to 7 in extents exceeding the effects of any presently know antibiotics. Then resetting in which Enterobacteriaceae, Bifidobacteriaceae and Clostridium difficile temporarily outnumber Bacteroides, Roseburia and Faecalibacterium prausnitzii, and after that decline with normalization of these bacteria to initial values. Conclusions: The colon is a bioreactor containing many potential pathogens. The mucus barrier shields the host from bacteria. The events following stroke stress the pivotal role of the brain in maintaining this shield and indicate an existence of emergency brakes that temporary terminate the biofermentation.