You should not try draining an abscess by pressing on it because it may spread infection to a deeper tissue. An abscess is a collection of pus that has built up within the tissue of the body. A skin abscess can be as a result of a bacterial infection that occurs when a bacteria such as staphylococcus aureus enter the body through a hair follicle or through wound or injury that has punctured or broken the skin. The abscess is drained using a needle, an incision is made on the skin over the abscess, then a thin plastic tube called drainage catheter into it, then the pus is drained.