Cellulitis usually begins as a small area of pain and redness on the skin. This area spreads to surrounding tissues, resulting in the typical signs of inflammation -- redness, swelling, warmth, and pain. A person with cellulitis can also develop fever and/or swollen lymph nodes in the area of the infection.
Cellulitis is a bacterial infection of the skin and tissues beneath the skin. Unlikeimpetigo, which is a very superficialskin infection, cellulitis is a bacterial skin infection that also involves the skin's deeper layers: the dermis and subcutaneous tissue.
The main bacteria responsible for cellulitis areStreptococcusandStaphylococcus("staph"), the same bacteria that can causeimpetigoand other diseases.MRSA(methicillin-resistantStaph aureus) can also cause cellulitis. Sometimes, other bacteria (for example,Hemophilus influenzae,Pneumococcus, andClostridiumspecies) may cause cellulitis as well.
Cellulitis is fairly common and affects people of all races and ages. Men and women appear to be equally affected. Although cellulitis can occur in people of any age, it is most common in middle-aged and elderly people. Cellulitis is not contagious.
Cellulitis may occur anywhere on the body; the legs are a common location.
In special circumstances, such as following surgery ortraumawounds, cellulitis can develop in the abdomen or chest areas. People with morbidobesitycan also develop cellulitis in the abdominal skin. Special types of cellulitis are sometimes designated by the location of the infection. Examples include
The majority of cellulitis infections are caused by infection with eitherstrep(Streptococcus) or staph (Staphylococcus) bacteria.
The most common bacteria that cause cellulitis are beta-hemolytic streptococci (groups A, B, C, G, and F). A form of rather superficial cellulitis caused bystrepis called erysipelas and is characterized by spreading hot, bright red circumscribed area on the skin with a sharp, raised border. Erysipelas is more common in young children. The so-called "flesh-eating bacteria" are, in fact, also a strain of strep bacteria that can sometimes rapidly destroy deeper tissues underneath the skin.Fasciitisis the term used to refer to inflammation of the very deep lining tissues called fascia. The streptococcal infection known asflesh-eating bacterial infectionis an example of fasciitis. Cellulitis, when untreated, may rarely spread to the deeper tissues and cause serious fasciitis.
Staph (Staphylococcus aureus), including methicillin-resistantstrains(MRSA), is another common type of bacteria that causes cellulitis. There is a growing incidence of community-acquired infections due to methicillin-resistant S. aureus (MRSA), a particularly dangerous type ofstaph infectionthat is resistant to many antibiotics, including methicillin, and is therefore more difficult to treat.
Cellulitis can be caused by many other types of bacteria. In children under 6 years of age,H.flu(Hemophilus influenzae) bacteria can cause cellulitis, especially on the face, arms, and upper torso. Cellulitis from a dog or cat bite or scratch may be caused by thePasteurella multocidabacteria, which has a very short incubation period of only four to 24 hours.Aeromonas hydrophilia,Vibriovulnificus, and other bacteria are causes of cellulitis that develops after exposure to freshwater or seawater.Pseudomonasaeruginosais another type of bacteria that can cause cellulitis, typically after a puncturewound.
Cellulitis is not contagious because it is a soft tissue infection of the skin's deeper layers (the dermis and subcutaneous tissue), and the skin's top layer (theepidermis) provides a cover over the infection. In this regard, cellulitis is different fromimpetigo, in which there is a very superficial skin infection that can be contagious.
Primary care specialists, including internists and family medicine specialists, treat cellulitis. For patients who seek medical treatment at an urgent care center or emergency department,emergency medicinespecialists may be the treating physicians. Sometimes infectious disease specialists or surgeons may be involved in the medical treatment of cellulitis.
Cellulitis has characteristic symptoms and signs.
The signs of cellulitis include
Any skin wound or ulcer that produces these symptoms or signs may be developing cellulitis.
Other forms of noninfectious inflammation may mimic cellulitis.
Most commonly, cellulitis develops in the area of a break in the skin, such as a cut, small puncture wound, orinsect bite. In some cases when cellulitis develops without an apparent skin injury, it may be due to microscopic cracks in the skin that are inflamed or irritated. It may also appear in the skin near ulcers or surgical wounds.
In other circumstances, cellulitis occurs where there has been no skin break at all, such as with chronicleg swelling(edema). A preexisting skin infection, such as anathlete's foot(tinea pedis) or impetigo can be a risk factor for the development of cellulitis. Likewise, inflammatory medical conditions or diseases of the skin such aseczema,psoriasis, or skin damage caused byradiation therapycan lead to cellulitis.
People who havediabetesor diseases that compromise the function of the immune system (for example,HIV/AIDSor those receivingchemotherapyordrugsthat suppress the immune system) are particularly prone to developing cellulitis.
Conditions or diseases that reduce the circulation of blood in the veins or that reduce the circulation of the lymphatic fluid (such asvenous insufficiency, obesity,pregnancy, or surgeries) also increase the risk of developing cellulitis.
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首先,它对医生区分是至关重要的whether or not the inflammation is due to an infection. The history and physical exam can provide clues in this regard, as can sometimes an elevated white blood cell count. Culture for bacteria may also be of value in making a diagnosis, but in many cases of cellulitis, the concentration of bacteria may be low and cultures fail to demonstrate the causative organism. In this situation, cellulitis is commonly treated with antibiotics that are designed to eradicate the most likely bacteria to cause the particular form of cellulitis. If a pus-filledabscessis present, surgical drainage is typically required.
When it is difficult or impossible to distinguish whether or not the symptoms are due to an infection, doctors sometimes treat them with antibiotics just to be sure. If the condition does not respond, it may need to be addressed by different methods dealing with types of inflammation that are not infected. For example, if the inflammation is thought to be due to an autoimmune disorder, treatment may be with acorticosteroid.
Antibiotics, such as derivatives ofpenicillinor other types of antibiotics that are effective against the responsible bacteria, are used to treat cellulitis. If the bacteria turn out to be resistant to the chosen antibiotics, or in patients who areallergicto penicillin, other appropriate antibiotics can be substituted. Sometimes the treatment requires the administration of intravenous antibiotics in a hospital setting, since oral antibiotics may not always provide sufficient penetration of the inflamed tissues to be effective. In certain cases, intravenous antibiotics can be administered at home or at an infusion center.
The following are some examples of antibiotics that have been used to treat cellulitis:
In all cases, physicians choose a treatment based upon many factors, including the location and extent of the infection, the type of bacteria causing the infection, and the overall health status of the patient.
Under some circumstances, cellulitis can be prevented by proper hygiene, treating chronicswelling of tissues(edema), care of wounds orcuts. In other cases, microscopic breaks in the skin may not be apparent and infection may develop. In general, cellulitis in a healthy person with an intact immune system is preventable by avoiding skin surface wounds. In people with predisposing conditions (see above) and/or weakened immune systems, cellulitis may not always be preventable.
Cellulitis is a treatable condition, but antibiotic treatment is necessary to eradicate the infection and avoid complications and the spread of the infection. Most cellulitis can be effectively treated with oral antibiotics at home. Sometimes hospitalization and intravenous antibiotics are required if oral antibiotics are not effective.
Sepsisis a serious complication of cellulitis. If not properly treated, cellulitis can occasionally spread to the bloodstream and cause a serious bacterial infection of the bloodstream that spreads throughout the body (sepsis).
Cellulitis may continue to spread and not resolve until antibiotic treatment is used. Typically, the symptoms disappear three to 10 days after you have begun taking antibiotics.
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