Brain abscess is a fatal infectious pathology of the central nervous system for which our CHU provides a referent function and supports patients suspected and diagnosed with a cerebral abscess in the area of the regional hospital group (GHT). Through the routine activity of the Microbiology laboratory of the IHU Méditerranée Infection, more than 180 diagnosed patients have been investigated in 9 years, an average of 20 patients per year. The mortality of brain abscesses is currently measured at 15% despite well-established diagnostic and therapeutic protocols in the literature, associating surgical drainage of abscess and administration of probabilistic antibiotics. Our hypothesis is that established protocols take into account incomplete microbiological documentation of cerebral abscesses and therefore anti-infectious therapy that may not be strictly adapted to the causative microorganisms. Our hypothesis is based on our own work as well as the literature data, showing that current approaches only target bacteria but that these approaches leave aside other living worlds such as Archaea. Indeed, investigators have recently shown for the first time that methanogens, which are Archaea microorganisms, constitute part of the flora responsible for certain cerebral abscesses and that they have a direct pathogenic role in cerebral abscesses. More specifically, the diagnosis of cerebral abscess includes several clinical and microbiological situations that are not all of the same therapeutic. Investigator propose to collect 20 abscesses. A collection of abscesses is performed systematically during the diagnosis for bacteriological analysis. There will be no further examination. The main objective of this clinical research project is to establish the repertoire of microorganisms responsible for brain abscesses; and as a secondary objective to define the different clinical entities forming the cerebral abscesses.