A brain abscess is a collection of pus enclosed in the brain tissue, caused by a bacterial or fungal infection. A brain abscess can develop as a complication of an infection, trauma or surgery. They are rare, although people with weakened immune systems (such as people with HIV or those who have received an organ transplant) are more likely to get a brain abscess.
This type of infection usually begins in one of these ways:
It spreads from a nearby site, such as a middle ear infection, sinus infection or dental abscess.
Blood carries the infection from further away in the body to the brain.
Infectious organisms enter the brain through a penetrating injury, such as a gunshot wound, or from neurosurgical procedures or facial trauma.