Treatment of Bacterial Skin Infections

Bacterial skin infections are very common, resulting in several million visits to health care professionals annually.[1] Most of the time, the infections are mild and easily treated with oral antibiotics or drainage of pus, if present. But untreated infections and infections in certain vulnerable patients can quickly worsen and may lead to severe complications, making it important that patients know the symptoms of a bacterial skin infection and how to treat it.

Types and causes of infections

Bacterial skin infections are first classified based on the presence or absence of pus.[2] Pus-filled lesions, which are skin abscesses or boils, require prompt drainage.

There are two main types of non-pus-filled bacterial skin infections. Cellulitis involves the middle layer of the skin and deeper tissues, while erysipelas is an infection of the more superficial skin layers.[3] Cellulitis typically involves redness, swelling, warmth and pain in the affected area of skin. Patients may also experience fever, chills, fatigue and muscle aches.[4] Cellulitis can spread rapidly to other parts of the body, including the lymph nodes and bloodstream. If untreated, it can be life-threatening.[5] Erysipelas involves a red rash with raised borders on the legs, face or arms.[6]

Streptococcal (routinely referred to as “strep”) and staphylococcal (“staph”) bacteria are the most common causes of bacterial skin infections.[7],[8],[9] In recent years, a strain of staph has emerged known as methicillin-resistant staph aureus (MRSA), which is resistant to penicillin-like antibiotics. In a 2013 study, among skin and soft tissue infections having positive tests for staph, MRSA was detectable in nearly half of these infections.[10]

Common risk factors for cellulitis and erysipelas include open skin wounds or cracked or peeling skin; insect or animal bites; the use of steroids or other medications that suppress the immune system;[11] obesity; and diseased blood vessels, skin ulcers and swelling, especially in the legs.[12]

Severity and treatment recommendations

Skin abscesses and boils need to have the pus drained by a physician as soon as possible.[13] For patients with healthy immune systems and no fever or other signs of a severe infection, antibiotics are not needed following drainage.

For cellulitis and erysipelas, the severity of the infection determines the choice of treatment.[14] Mild infections consist of only a rash. Moderate infections involve a fever, increased heart or breathing rate, or elevated white blood cell counts. Patients are deemed to have a severe infection if they have any of those symptoms or signs and any of the following:

• Failure of the infection to resolve with oral antibiotics.
• An immune system that is compromised in any way.
• Certain signs that the infection involves deep layers of the skin.
• Low blood pressure or other signs of organ dysfunction, such as acute kidney damage or mental status changes.

In 2014, the Infectious Diseases Society of America (IDSA) released guidelines for the treatment of bacterial skin infections.[15] For mild cellulitis or erysipelas in otherwise healthy patients, the guidelines recommended that no tests be done and that the infection be treated with oral antibiotics. Penicillin (PENICILLIN-VK), a penicillin-like antibiotic (cephalexin [KEFLEX] or dicloxacillin [available in generic only]), or clindamycin (CLEOCIN) are recommended for a total of five days. These antibiotics, along with another class known as macrolides (for example, azithromycin [ZITHROMAX]), have been shown to be equally safe and effective in clearing up the infection or improving symptoms.[16]

For moderate to severe cellulitis or erysipelas, and in mild infections occurring in patients vulnerable to complications from the infection, the IDSA guidelines recommend that skin and blood samples be taken to determine the specific bacteria causing the infection and whether the infection has spread to the blood.[17] Patients with these infections are usually admitted to the hospital, where they are given intravenous antibiotics.

The IDSA guidelines recommend that patients with cellulitis or erysipelas and evidence of MRSA on their body, or who may be at risk for MRSA infection, should be treated with antibiotics (for example, vancomycin [VANCOCIN]) that are effective against MRSA.[18]

Unfortunately, evidence-based recommendations are not always followed in practice. A study found that about half of uncomplicated skin infections in a medical practice involved unnecessary antibiotic exposure.[19] The two most common forms of antibiotic overuse were excessive treatment, for 10 days or more, and using more than one antibiotic for the infection.

Recurrences of cellulitis or erysipelas

For patients with at least one episode of cellulitis or erysipelas, an estimated 14 percent will go on to have a recurrence of the infection within one year, and 45 percent will have a recurrence within three years, usually in the same location on the body.[20] Antibiotics were shown in one analysis to reduce recurrences of these infections by more than one-half,[21] but the analysis was limited in several ways, making the effect of such treatment uncertain.[22]

The IDSA guidelines recommend that antibiotics (oral or injectable penicillin, or oral erythromycin [ERYTHROCIN STEARATE]) be considered for patients with three to four episodes of cellulitis or erysipelas in a one-year period for as long as the patient remains at high risk for a recurrence, but this recommendation is controversial.[23],[24] In addition to the uncertainty over its effectiveness for many patients, there also are risks to long-term antibiotic use, such as the development of antibiotic resistance, drug allergy and C. difficile infection.[25]

What You Can Do

There are many different types and causes of skin rashes, so not every rash will require antibiotics or even any treatment at all. You should see a health care professional to determine whether your rash is a bacterial skin infection. If it is, and there is evidence of pus, your doctor should have it drained as soon as possible and further treatment with antibiotics is not necessary unless you have a weak immune system or signs of a severe infection.

If there is no evidence of pus, then five days of oral antibiotics is the treatment of choice. However, if your immune system is compromised in any way, such as through an HIV infection, cancer, chemotherapy, or steroids or other immune-suppressing medications, then your doctor may want to take skin and blood samples. You may need to be admitted to the hospital in order to receive supervised treatment with intravenous antibiotics. It is always important to inform your doctor of allergies to any antibiotics, such as penicillin, as allergic reactions to medications can be life-threatening.

If you take antibiotics and develop abdominal pain or diarrhea, see your doctor as these can be signs of a potentially serious infection with the C. difficile bacteria brought on by the antibiotic.

Losing weight, reducing chronic leg swelling through physical activity or leg tights, resolving any chronic allergic skin conditions such as eczema, and thoroughly cleaning any skin wounds with soap and water are just some of the ways to avoid cellulitis and erysipelas.[26]

If you have had two or more episodes of cellulitis or erysipelas, you should discuss the benefits and risks of taking long-term antibiotics to prevent further infections. The effectiveness and safety of such treatment depend on several factors. For many patients, the risks likely outweigh the benefits.

References

[1] Hersh AL, Chambers HF, Maselli JH, Gonzales R. National trends in ambulatory visits and antibiotic prescribing for skin and soft-tissue infections. Arch Intern Med. 2008;168(14):1585-1591.

[2] Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):e10-52.

[3] National Institute of Allergy and Infectious Diseases. Cellulitis and Erysipelas. https://www.niaid.nih.gov/topics/cellulitiserysipelas/Pages/default.aspx. Accessed August 15, 2016.

[4] National Institutes of Health. Cellulitis. Medline Plus. https://medlineplus.gov/ency/article/000855.htm. Accessed August 16, 2016.

[5] Mayo Clinic. Cellulitis. http://www.mayoclinic.org/diseases-conditions/cellulitis/basics/definition/con-20023471. Accessed August 16, 2016.

[6] National Institute of Allergy and Infectious Diseases. Cellulitis and erysipelas. https://www.niaid.nih.gov/topics/cellulitiserysipelas/Pages/default.aspx. Accessed August 16, 2016.

[7] Ibid.

[8] National Institutes of Health. Cellulitis. Medline Plus. https://medlineplus.gov/ency/article/000855.htm. Accessed July 19, 2016.

[9] Merck Manual. Cutaneous Abscess. http://www.merckmanuals.com/professional/dermatologic-disorders/bacterial-skin-infections/cutaneous-abscess. Accessed August 29, 2016.

[10] Ray GT, Suaya JA, Baxter R. Incidence, microbiology, and patient characteristics of skin and soft-tissue infections in a U.S. population: A retrospective population-based study. BMC Infect Dis. 2013 May 30;13:252.

[11] National Institutes of Health. Cellulitis. Medline Plus. https://medlineplus.gov/ency/article/000855.htm. Accessed August 16, 2016.

[12] Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):e10-52.

[13] Ibid.

[14] Ibid.

[15] Ibid.

[16] Ferreira A, Bolland MJ, Thomas MG. Meta-analysis of randomised trials comparing a penicillin or cephalosporin with a macrolide or lincosamide in the treatment of cellulitis or erysipelas. Infection. 2016 Apr 16.

[17] Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):e10-52.

[18] Ibid.

[19] Hurley HJ, Knepper BC, Price CS, Mehler PS, Burman WJ, Jenkins TC. Avoidable antibiotic exposure for uncomplicated skin and soft tissue infections in the ambulatory care setting. Am J Med. 2013;126(12):1099-106.

[20] Raff AB, Kroshinsky D. Cellulitis: A review. JAMA. 2016;316(3):325-337.

[21] Oh CC, Ko HC, Lee HY, et al. Antibiotic prophylaxis for preventing recurrent cellulitis: A systematic review and meta-analysis. J Infect. 2014;69(1):26-34.

[22] Raff AB, Kroshinsky D. Cellulitis: A review. JAMA. 2016;316(3):325-337.

[23] Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):e10-52.

[24] Raff AB, Kroshinsky D. Cellulitis: A review. JAMA. 2016;316(3):325-337.

[25] Ibid.

[26] Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):e10-52.