Sexually transmitted diseases (STDs), pyogenic bacteria and certain fungal infections commonly cause yellow pus. The pus, created when malicious bacteria release enzymes that destroy and invade proteins in the body, can exude directly from infected skin and membranes or be contained inside an abscess or pustule. Types of infections that can cause yellow pus include strep throat, staph, purulent conjunctivitis and paronychia. This pus is contagious and contains an abundance of leukocytes, or white blood cells, that have mixed with malicious bacteria in an attempt to halt the infection.
Gonorrhea is the main STD likely to generate yellow pus on or inside the genitalia. The head of the penis, the urethra, and the cervix are usually the site of infection and the locations that harbor the greatest amount of pus. Often this pus is discharged during urination, which can be accompanied by sharp pain. Antibiotics are the leading treatment for gonorrhea; once the bacteria are treated, the pus dissipates.
Strep throat is a bacterial infection caused by the streptococcus bacterium of the Group A variety. It results in yellow pus at the back of the throat and on or between the tonsils. This pus is generally accompanied by swelling in the throat or lymph nodes as well as painful swallowing; fever or chills are also possible. Antibiotics are generally effective in killing the bacteria thriving inside the pus and ending the strep throat infection. In addition to strep, bacteria causing the common cold can also generate yellow pus in the throat.
Infections caused by regular and methicillin-resistant staphylococcus aureus (MRSA) create lesions and craters on the skin that brim with yellow pus as bacteria eat away at the flesh. Often lesions appear in clusters. Normally acquired through hospital exposure, staph infections can occasionally be contracted from microflora at home or in community facilities. Regular staph can be treated with methicillin, but MRSA requires stronger and ongoing antibiotic therapy.
Yellow pus is typical during an eye infection known as purulent conjunctivitis. During such an infection, the membrane covering the eyeball takes on a pink or red tinge and can ooze yellow pus that cakes or crusts at the corners of the eye. This illness generally strikes children and is typically treated with eye drops containing azithromycin.
Paronychia is a fungal infection that afflicts fingernails and toenails, causing pus to accumulate underneath the nail. The cuticles and surrounding flesh generally become red, sore and inflamed as pus spills onto the cuticle from under the nail. Surgical drainage or the application of antibiotics, such as amoxicillin, is a typical treatment for this condition.