What Is Skin Infection (Cellulitis)?
Cellulitis is a bacterial infection that can affect the skin of any part of the body. Cellulitis most commonly appears on the legs in adults and on the head in children. It can be the result of any condition that compromises the protective barrier of the skin.
The most common symptoms are a growing region of redness that is warm to touch and painful when pressed. Symptoms indicating that the disease has advanced include fever, chills, headaches, vomiting, and feeling ill.
Antibiotics are required to treat the skin infection, and, importantly, they can prevent the spread of the infection to the lymphatic system or the bloodstream.
You should visit your primary care physician within the next 24 hours to examine the infection and possibly provide antibiotics.
How common is skin infection (cellulitis)?
Symptoms that always occur with skin infection (cellulitis):
- Red rash
- Painful rash
Skin infection (cellulitis) is also known as
- Skin infection
- Erysipelas (although this is a slightly different condition)
Skin Infection (Cellulitis) Symptoms
The most common symptoms are those that impact the infected skin and the region around the skin. These symptoms include:
- Redness of the skin that grows larger with time
- Warmth of the skin
- Tenderness/pain of the skin
- Swelling of the skin
- Red line formation: A red line traveling from the original area of redness can sometimes be seen traveling up the leg or arm. This can indicate the spread of the infection through the lymphatic system.
- Ulceration of the skin: In severe cases the infection can destroy the outer layers of skin, resulting in a pit (ulcer).
- Swelling of the lymph nodes: The lymph nodes near the site of infection, such as those in the groin, armpit, and neck, can be felt as little bumps, like olive pits, that can indicate inflammation or infection of the nodes.
Cellulitis can also affect the entire body, especially if the infection enters the bloodstream. These symptoms can include:
- Tiredness/lack of energy
- Feeling sick
- Low blood pressure
- Fast heartbeat
Complications of Cellulitis
If cellulitis goes untreated, it can lead to serious infection at the region of the initial infection and around the body. Some complications of leaving cellulitis untreated include:
- Abscess: Bacteria and white blood cells (pus) can form under the skin. This pocket may cause severe pain and may need to be drained if it is large.
- Necrotizing fasciitis: Infection can spread under the skin layer and into the fascia layer and cause a severe, rapidly progressing infection that can destroy the soft tissue.
- Bacteremia: Infection of the bloodstream
- Lymphangitis/lymphadenopathy: Infection of the lymph ducts and/or lymph nodes.
- Septic arthritis: Infection of a nearby joint.
Skin Infection (Cellulitis) Causes
Cellulitis is a relatively common condition. All cases of cellulitis are due to the compromise of the skin as a protective barrier. Once the skin is broken down by trauma or disease, bacteria that are already living on top of the skin can get underneath, resulting in infection. Within a few days, the bacteria will increase in number, and the characteristic redness, warmth, and pain will appear. Protecting oneself from trauma and certain diseases listed below can be the best way to prevent the development of cellulitis.
Traumatic causes of cellulitis
The following causes of cellulitis can occur in anyone without any predisposing factors:
- Cuts to skin
- Surgical wounds
- Insect bites (spider, ant, tick, etc.)
- Animal bites (dog, cat, etc.)
- Scratching itchy skin: Especially those with scratching due to eczema
- Intravenous drug injection
- Fist fighting
Chronic disease causes of cellulitis
Another way that the skin can break down is the long-term presence of certain diseases:
- Immunosuppression: This is a weakened immune system found in people taking drugs that decrease immune activity or those with HIV/AIDS.
- Venous disease: People with varicose veins or venous insufficiency are at an increased risk.
- Arterial disease: People with a narrowing of the arteries of the leg are at increased risk.
- Ulceration of the skin
- Leg swelling
Cellulitis can be caused by a number of bacterial species, but the most common causes include:
- Staphylococcus aureus (including methicillin-resistant Staphylococcus aureus or MRSA)
- Streptococcus pyogenes
- Pasteurella multocida
- Vibrio vulnificus
Treatment Options and Prevention
The most common and important treatment for cellulitis is a rapid delivery of antibiotics. If cellulitis is suspected, your physician may draw a border around the red area with a marker. This line will help them determine whether or not the infection is spreading (expanding) or improving (getting smaller). Your physician will also draw blood to check if bacteria have entered the bloodstream before giving you antibiotics. In some cases, images will be taken to determine if the cellulitis has communicated with a joint space. Imaging techniques may include computed tomography (CT) scan, magnetic resonance imaging (MRI), or ultrasound.
Antibiotics can be delivered by mouth or intravenously (IV). The selection of antibiotics depends on the severity of the infection. If the infection is severe, you may be admitted to the hospital for IV antibiotics and monitoring of the infection. Less severe cases can receive antibiotics by mouth with close follow-up. Some examples of antibiotics used in cellulitis include:
- Cefazolin (Ancef)
- Cefalexin (Keflex)
- Trimethoprim-sulfamethoxazole (Bactrim)
- Amoxicillin-clavulanate (Augmentin)
If an abscess (a pocket of pus) is suspected, then the surgical drainage of the abscess may be required.
It is very important to elevate the extremity during treatment. Treatment failure can occur simply due to failure to elevate the limb. In addition to antibiotics, you can take certain measures to make recovery more comfortable, such as making sure to rest the affected limb and taking painkillers and anti-fever drugs. Steroids may also be used to assist in treatment.
You can expect improvement beginning at 24 hours after starting antibiotics . If the infection is not improving or is getting larger, immediate medical attention should be sought.
The best ways to prevent this disease are to avoid trauma to the skin:
- Wear protective clothing
- Moisturize skin
- Avoid situations where skin trauma is likely
- Proper hygiene
- Wound care: If there is a cut, scrape, or wound, wash with soap and water multiple times per day and consider an antibiotic ointment.
- Use insect repellent
- Avoid aggressive animals
- Avoid scratching bug bites or eczema
- Avoid tattooing or ensure clean and safe practices
- Do not inject intravenous substances
In addition, treatment of chronic conditions can decrease the risk of developing cellulitis. You should seek care for the appropriate management of the following.
- Diabetes: This includes a regular inspection of the legs and feet for the formation of any ulcers.
- Leg vein disease
- Leg artery disease
- Chronic wounds
In some people who have had cellulitis two or more times, a preventative penicillin antibiotic may be given.
When to Seek Further Consultation
Any case of cellulitis must be seen by a nurse practitioner, physician assistant, or physician since the condition requires treatment with antibiotics, which are by prescription only.
You should seek care if you notice an area of warm, tender redness that is growing larger. Further signs that such an area of redness could be cellulitis are a recent history of traumatic injury to the same area, a history of previous cellulitis, pus drainage from the red area, and the development of fever.
You can ordinarily be seen by your primary care physician or at an urgent care facility, but if these methods of care are not immediately available, an emergency room visit is necessary.
After the treatment of cellulitis, you should schedule a follow-up appointment. You should also schedule follow-up care with the physician who provides care for your diabetes, vein disease or HIV/AIDS, if applicable, since the development of cellulitis may indicate inadequate treatment of these other conditions.
Questions Your Doctor May Ask to Diagnose
To diagnose this condition, your doctor would likely ask about the following symptoms and risk factors.
- Are you sick enough to consider going to the emergency room right now?
- Have you experienced any nausea?
- How severe is your fever?
- Is your fever constant or come-and-go?
- Has your fever gotten better or worse?
The above questions are also covered by our A.I. Health Assistant.
- Cellulitis symptoms & causes. Mayo Clinic. Published April 10, 2018. Mayo Clinic Link
- Cellulitis. American Academy of Dermatology. AAD Link
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- Ellis Simonsen SM, Van Orman ER, Hatch BE, et al. Cellulitis incidence in a defined population. Epidemiology and Infection. 2006;134(2):293-9. Cambridge Link
- Bailey E, Kroshinsky D. Cellulitis: Diagnosis and management. Dermatol Ther. 2011;24(2):229-239. PubMed Link
- 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):147-159. Oxford Academic Link