Cellulitis | |
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Skin cellulitis | |
Specialty | Infectious disease, dermatology |
Symptoms | Red, hot, painful area of skin, fever[1][2] |
Duration | 7–10 days[2] |
Causes | Bacteria[1] |
Risk factors | Break in the skin, obesity, leg swelling, old age[1] |
Diagnostic method | Based on symptoms[1][3] |
Differential diagnosis | Deep vein thrombosis, stasis dermatitis, erysipelas, Lyme disease, necrotizing fasciitis[1][4][5] |
Treatment | Elevation of the affected area[4] |
Medication | Antibiotics such as cephalexin[1][6] |
Frequency | 21.2 million (2015)[7] |
Deaths | 16,900 (2015)[8] |
Cellulitis is usually[9] a bacterial infection involving the inner layers of the skin.[1] It specifically affects the dermis and subcutaneous fat.[1] Signs and symptoms include an area of redness which increases in size over a few days.[1] The borders of the area of redness are generally not sharp and the skin may be swollen.[1] While the redness often turns white when pressure is applied, this is not always the case.[1] The area of infection is usually painful.[1] Lymphatic vessels may occasionally be involved,[1][4] and the person may have a fever and feel tired.[2]
The legs and face are the most common sites involved, although cellulitis can occur on any part of the body.[1] The leg is typically affected following a break in the skin.[1] Other risk factors include obesity, leg swelling, and old age.[1] For facial infections, a break in the skin beforehand is not usually the case.[1] The bacteria most commonly involved are streptococci and Staphylococcus aureus.[1] In contrast to cellulitis, erysipelas is a bacterial infection involving the more superficial layers of the skin, present with an area of redness with well-defined edges, and more often is associated with a fever.[1] The diagnosis is usually based on the presenting signs and symptoms, while a cell culture is rarely possible.[1][3] Before making a diagnosis, more serious infections such as an underlying bone infection or necrotizing fasciitis should be ruled out.[4]
Treatment is typically with antibiotics taken by mouth, such as cephalexin, amoxicillin or cloxacillin.[1][6] Those who are allergic to penicillin may be prescribed erythromycin or clindamycin instead.[6] When methicillin-resistant S. aureus (MRSA) is a concern, doxycycline or trimethoprim/sulfamethoxazole may, in addition, be recommended.[1] There is concern related to the presence of pus or previous MRSA infections.[1][2] Elevating the infected area may be useful, as may pain killers.[4][6]
Potential complications include abscess formation.[1] Around 95% of people are better after 7 to 10 days of treatment.[2] Those with diabetes, however, often have worse outcomes.[10] Cellulitis occurred in about 21.2 million people in 2015.[7] In the United States about 2 of every 1,000 people per year have a case affecting the lower leg.[1] Cellulitis in 2015 resulted in about 16,900 deaths worldwide.[8] In the United Kingdom, cellulitis was the reason for 1.6% of admissions to a hospital.[6]