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A skin abscess is a pocket of pus.
It is similar to a pimple, but larger and deeper under the skin. It forms when the body tries to protect itself from an infection by creating a wall around it. The pus contains bacteria, white blood cells, and dead skin. The most common bacteria are Staphylococcus aureus (known as “staph”) and methicillin-resistant Staphylococcus aureus (known as MRSA). Most people carry these bacteria on their skin yet never develop an infection. However, when the bacteria penetrate the skin (through a cut, along a hair follicle, or under the edges of a wound), they may lead to an abscess.
Signs and Symptoms
A skin abscess is round and feels firm and squishy due to the thick membrane around it and the liquid pus inside. It is usually painful, and the overlying skin is often red. Sometimes there is a pinpoint opening in the center (a punctum). This is the weakest part of the wall and pus might spontaneously drain through it.
How to Treat It
The only certain way to treat an abscess is to open the pocket and drain the pus. This is known as an “incision and drainage.” It is a simple procedure that can be done with local anesthesia. A surgical knife is used to cut a hole in the wall of the abscess and empty it of pus.
Sometimes the doctor will pack the wound or leave a wick, which means stuffing the empty pocket with a ribbon of gauze. This allows the pus to continue draining and prevents the abscess from returning. Your doctor will instruct you to gently pull out a small part of the wick every day until it all comes out. Eventually, the entire gauze will be removed and the wound will heal from inside out. If the cavity is large, you may be asked to come back to the office so the gauze can be replaced entirely. Warm, moist compresses or baths are also recommended to keep the wound open and draining.
If the area around the abscess is red and warm to touch it could be a sign of cellulitis, an infection of the superficial layer of the skin. In this case, antibiotics may be prescribed.
Recurrent abscesses could be a sign of MRSA infection. Your doctor may test for MRSA and prescribe antibiotics directed at treating these particular bacteria.
Sometimes an abscess is not ready to be drained, which means that it is not yet organized into a defined pocket. Antibiotics may be effective at treating this infection and prevent it from becoming an abscess.
Fever is a sign that the infection may be deeper than can be seen with the naked eye and may be another reason to use antibiotics.
If antibiotics are given, it is crucial to finish all of them as instructed, even if the infection looks better. This prevents bacteria from becoming resistant to antibiotics.
Left untreated, an abscess can lead to serious complications and may become life-threatening.
Linder KA, Malani PN. Cellulitis. JAMA. 2017;317(20):2142.
Mayo Clinic website. Boils and carbuncles. www.mayoclinic.org/diseases-conditions/boils-and-carbuncles/symptoms-causes/syc-20353770
Medline Plus. Abscess. medlineplus.gov/ency/article/001353.htm
Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
Source: Raff AB, Kroshinsky D. Cellulitis: a review. JAMA. 2016;316(3):325-337.
Baiu I, Melendez E. Skin Abscess. JAMA. 2018;319(13):1405. doi:10.1001/jama.2018.1355
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