What is pus?

Pus - the pus we see oozing out from a septic cut is made up of the dead bodies of white blood cells which have fought against the infection. These white cells, or corpuscles, live in the blood and float around the body ready to fight infection. There are at least five kinds of white cells. The ones which fight the kind of infections that happens when a spot or a cut goes bad are called Leucocytes. A speck of blood, the size of a pinhead, normally contains about 5,000 leucocytes. But it may have 30,000 in a really bad septic wound. This is because the leucocytes gather at a point of infection and multiply. Antibodies in the blood help to fight bacteria. When these have killed the bacteria, the white cells move into destroy them. If a doctor suspects that the blood may not contain enough antibodies to counteract the infection, he prescribes extra antibiotics, like penicillin, which do the same job. Often the infection is defeated even without help from injections and pills, but not before many of the white cells have been killed, and discarded as pus.