Brain abscesses. Coloured magnetic resonance imaging (MRI) scans of an axial (horizontal) section through the brain of a 38 year old patient with cerebral abscesses (dark circles surrounded by white rings). The abscesses have been highlighted by the injection of a gadolinium contrast medium. Abscesses are a collection of pus in response to infection. They are often caused by Streptococcus bacteria, but other bacteria, fungi and parasites can also cause the disease. They exert pressure on brain tissue, causing symptoms such as headaches, drowsiness, confusion and seizures. Brain abscesses are usually linked to an underlying disease or a primary lesion elsewhere in the body, as they rarely occur by themselves. Treatment is by isolating the underlying cause and by taking antibiotics.