From the Guidelines
Cellulitis is a bacterial skin infection caused by Streptococcus and Staphylococcus bacteria, and treatment should include an antibiotic active against these organisms, with a recommended duration of 5 days, as stated in the 2014 update by the Infectious Diseases Society of America 1. Cellulitis is a common bacterial skin infection that affects the deeper layers of skin and the subcutaneous tissue, causing redness, swelling, warmth, and pain in the affected area. It most commonly occurs when bacteria enter through a break in the skin such as a cut, scrape, or insect bite. The most common organisms that cause cellulitis are:
- Streptococcus bacteria, particularly Streptococcus pyogenes (Group A strep)
- Staphylococcus bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) Other less common causative organisms include:
- Haemophilus influenzae
- Pseudomonas aeruginosa
- Vibrio vulnificus (especially in saltwater exposures)
- Pasteurella multocida (from animal bites)
- Various fungi in immunocompromised individuals Treatment typically involves antibiotics, with mild cases often treated with oral antibiotics like cephalexin, dicloxacillin, or clindamycin for 5 days, as a 5-day course of antimicrobial therapy is as effective as a 10-day course, if clinical improvement has occurred by 5 days 1. More severe cases may require intravenous antibiotics and hospitalization. Elevating the affected area, applying warm compresses, and taking pain relievers can help manage symptoms. Prompt treatment is essential to prevent the infection from spreading to the bloodstream or lymph nodes, which can lead to serious complications. The recommended duration of antimicrobial therapy is 5 days, but treatment should be extended if the infection has not improved within this time period, as stated in the 2014 update by the Infectious Diseases Society of America 1.
From the Research
Definition of Cellulitis
- Cellulitis is a bacterial skin and soft tissue infection that occurs when the physical skin barrier, the immune system, and/or the circulatory system are impaired 2.
- It is an infection involving the deep dermis and subcutaneous tissue, and is the most common reason for skin-related hospitalization 3.
- Cellulitis is a clinical diagnosis based on the history of present illness and physical examination, and lacks a gold standard for diagnosis 3, 4.
Causes of Cellulitis
- The majority of non-purulent, uncomplicated cases of cellulitis are caused by β-hemolytic streptococci or methicillin-sensitive Staphylococcus aureus 3.
- β-hemolytic streptococci were the dominating cause of cellulitis in all clinical subgroups, and group C or G streptococci were more frequently detected than group A streptococci 5.
- Staphylococcus aureus is the most common identified cause of cellulitis, outnumbering group A streptococcus by a ratio of nearly 2:1 6.
- Other pathogens, such as group A streptococcus and other bacteria, can also cause cellulitis 5, 6.
Clinical Presentation
- Clinical presentation with acute onset of redness, warmth, swelling, and tenderness and pain is typical 3.
- Physical examination typically demonstrates poorly demarcated unilateral erythema with warmth and tenderness 4.
- Cellulitis can be difficult to diagnose due to a number of infectious and non-infectious clinical mimickers, such as venous stasis dermatitis, contact dermatitis, eczema, lymphedema, and erythema migrans 3, 2.