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Skin bacterial abscess in Adult
See also in: Cellulitis DDx,Anogenital,Hair and Scalp
Other Resources UpToDate PubMed

Skin bacterial abscess in Adult

See also in: Cellulitis DDx,Anogenital,Hair and Scalp
Contributors: Lauren Strazzula MD, Susan Burgin MD, Lowell A. Goldsmith MD, MPH
Other Resources UpToDate PubMed


An abscess is a localized inflammatory process in which the white blood cells accumulate at the site of infection in the dermis and/or subcutaneous tissue, creating a collection of pus. Commonly associated pathogens are Staphylococcus aureus, streptococci, and normal skin flora. Trauma or any break in the skin barrier predisposes to abscess formation.

Lesions evolve over days to 1-2 weeks. They are usually painful / tender, erythematous, warm, and fluctuant masses that are sometimes associated with fever. A tender subcutaneous nodule with overlying erythema but minimal fluctuance may be an early presentation. Incision and drainage is the mainstay of therapy. In an otherwise healthy, ambulatory patient, the addition of antibiotics is not indicated. Indications for the addition of antibiotics may include patients who are systemically ill, have a high burden of disease (indicated by concomitant widespread folliculitis or associated cellulitis), are immunosuppressed, or have failed incision and drainage.

Methicillin-resistant S. aureus (MRSA) first emerged as an important nosocomial pathogen in the 1960s. In more recent years, community-acquired outbreaks of MRSA (CA-MRSA) have increasingly been described among healthy individuals lacking the traditional risk factors for such infections (intravenous [IV] drug use, incarceration, participation in contact sports, etc). These strains have a propensity for causing abscesses, furunculosis, and folliculitis and have a unique antibiotic susceptibility profile from health care-associated strains of MRSA (HA-MRSA).

It has been shown that the majority of purulent skin and soft tissue infections presenting to emergency rooms across the United States are caused by CA-MRSA.


L02.91 – Cutaneous abscess, unspecified

31928004 – Abscess of skin AND/OR subcutaneous tissue

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Differential Diagnosis & Pitfalls

Aspergillosis and other opportunistic infections, including Mycobacterium avium complex and Serratia, can present as an abscess in the immunocompromised patient.

The differential diagnosis of a tender, erythematous dermal or subcutaneous nodule in the immunosuppressed host must include bacterial, fungal, and mycobacterial organisms. These cannot be differentiated clinically and must be cultured to determine the causative organism.

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Last Updated:10/08/2017
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Patient Information for Skin bacterial abscess in Adult
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Contributors: Medical staff writer


An abscess is an infection characterized by a collection of pus underneath a portion of the skin. Bacteria commonly causing abscesses are Staphylococcus aureus and Streptococcus. These bacteria enter the skin through any cracks or injury to the skin. That area of skin then becomes red, tender, warm, and swollen over days to 1-2 weeks and a fever may develop. Abscesses can sometimes form if minor superficial skin infections are not treated appropriately and in a timely fashion. Most abscesses resolve quickly once appropriately treated.

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is a strain of "staph" bacteria resistant to antibiotics in the penicillin family, which have been the cornerstone of antibiotic therapy for staph and skin infections for decades. CA-MRSA previously infected only small segments of the population, such as health care workers and persons using injection drugs. However, CA-MRSA is now a common cause of skin infections in the general population. While CA-MRSA bacteria are resistant to penicillin and penicillin-related antibiotics, most staph infections with CA-MRSA can be easily treated by health care practitioners using local skin care and commonly available non-penicillin-family antibiotics. Rarely, CA-MRSA can cause serious skin and soft tissue (deeper) infections. Staph infections typically start as small red bumps or pus-filled bumps, which can rapidly turn into deep, painful sores. If you see a red bump or pus-filled bump on the skin that is worsening or showing any signs of infection (ie, the area becomes increasingly painful, red, or swollen), see your doctor right away. Many patients believe incorrectly that these bumps are the result of a spider bite when they arrive at the doctor's office. Your doctor may need to test (culture) infected skin for MRSA before starting antibiotics. If you have a skin problem that resembles a CA-MRSA infection or a culture that is positive for MRSA, your doctor may need to provide local skin care and prescribe oral antibiotics. To prevent spread of infection to others, infected wounds, hands, and other exposed body areas should be kept clean and wounds should be covered during therapy.

Factors that predispose individuals to developing an abscess include:
  • Any skin infection, especially those that are untreated
  • Diabetes
  • Obesity
  • Intravenous drug abuse
  • Weakened immune system due to underlying illness or medication

Who’s At Risk

Abscesses can occur in anyone and occur anywhere on the body.

You might be able to sense fluid in an abscess when you press on the abscess with a finger.

Signs & Symptoms

A worsening red, tender swelling that arises over a period of 1-2 weeks. The pus underneath the skin is usually not visible. You may have a fever or a general sense of not feeling well.

Self-Care Guidelines

There are no self-care options for abscesses. While waiting to see your doctor, you can try applying a warm compress to the affected area and take ibuprofen to help with the swelling and pain.

When to Seek Medical Care

A worsening red, tender swelling should prompt you to make an appointment with your physician as soon as possible. If the area involves your face, is spreading rapidly, or is in an area that severely limits your functionality, you should seek emergency care.


Your doctor may drain the pus and fluid collection by making a small incision in the skin after it has been numbed. This will drain a majority of the bacteria, helping the body fight the small amount that remains. This fluid may then be sent to a laboratory for testing (culture), but not necessarily. The culture can tell the doctor not only what type of bacterium is causing the infection but also what antibiotics will work best to treat it. This may take as little as 2-3 days. Your doctor may choose to have you start oral antibiotics aimed at treating the most common bacteria that cause abscesses while awaiting these results. However, if the infection is small and it has been drained, your doctor may decide to not treat you with oral antibiotics.

If your symptoms are not improving or it is determined that the bacterium is not one of the common types, your doctor may prescribe different antibiotics. If your doctor prescribes antibiotics, it is important to take the entire course as prescribed, even if you are feeling better or the infection appears to be gone after just a few days. If you have been taking antibiotics and the infection itself or the way you are generally feeling have not improved in about 2-3 days, return to see your doctor.


Bolognia, Jean L., ed. Dermatology, p. 1126. New York: Mosby, 2003.

Wolff, Klaus, ed. Fitzpatrick's Dermatology in General Medicine. 7th ed, pp. 874, 1702. New York: McGraw-Hill, 2008.
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Skin bacterial abscess in Adult
See also in: Cellulitis DDx,Anogenital,Hair and Scalp
A medical illustration showing key findings of Skin bacterial abscess : Abscess, Skin warm to touch, Painful skin lesion
Clinical image of Skin bacterial abscess - imageId=154367. Click to open in gallery.  caption: 'Abscesses on the forearm, one with an ulcer and crust.'
Abscesses on the forearm, one with an ulcer and crust.
Copyright © 2023 VisualDx®. All rights reserved.