Pus: Is a collection of white blood cells

Pus is a collection of white blood cells, microorganisms (like bacteria), and dead tissue. It can form at a bacterial infection. Learn more. Pus is a protein-rich fluid that forms when white blood cells fight infection. Learn about the causes, treatment, and color of pus , and when to see a doctor. Pus is a thick yellowish, whitish, or greenish fluid made up of dead white blood cells, dead tissues, and dead bacteria or fungi. Also called liquor puris or purulent exudate, it is produced as part of the body's response to an infection. Pus is a sticky thick yellowish or pale greenish fluid that is often contained in the blisters or rashes formed due to microbial infections. The treatment method(s) used for treating pus depends upon the cause of the pus and also the severity of the pus infection. Brownish pus is formed in liver abscess due to amoeba.