The aim of the study is to verify the hypothesis that the microbial colonisation of the gut is changed in patients after stroke and that the gut microbiome of severely affected stroke patients differs from that of patients with only a short disruption of blood circulation in the brain (transient ischemic attack, TIA). For this, the composition of gut microbiota in stool samples will be analyzed by 454 pyrosequencing. Further, the correlation of stroke-associated changes in the microbiome with immunological parameters will be analyzed.