Typically, this includes alpha-hemolytic streptococci, staphylococci, and bacteroides groups.Predisposing conditions for cellulitis include an insect or spider bite, blistering, an animal bite, tattoos, pruritic (itchy) skin rash, recent surgery, athletes foot, dry skin, eczema, injecting drugs (especially subcutaneous or intramuscular injection or where an attempted intravenous injection "misses" or blows the vein), pregnancy, diabetes, and obesity, which can affect circulation, as well as burns and boils, although debate exists as to whether minor foot lesions contribute. Occurrences of cellulitis may also be associated with the rare condition hidradenitis suppurativa or dissecting cellulitis.The appearance of the skin assists a doctor in determining a diagnosis. A doctor may also suggest blood tests, a wound culture, or other tests to help rule out a blood clot deep in the veins of the legs. Cellulitis in the lower leg is characterized by signs and symptoms similar to those of a deep vein thrombosis, such as warmth, pain, and swelling (inflammation). Reddened skin or rash may signal a deeper, more serious infection of the inner layers of skin. Once below the skin, the bacteria can spread rapidly, entering the lymph nodes and the bloodstream and spreading throughout the body. This can result in influenza-like symptoms with a high temperature and sweating or feeling very cold with shaking, as the affected person cannot get warm.In rare cases, the infection can spread to the deep layer of tissue called the fascial lining. Necrotizing fasciitis, also called by the media "flesh-eating bacteria", is an example of a deep-layer infection. It is a medical emergency.
When methicillin-resistant S. aureus (MRSA) is a concern, doxycycline or trimethoprim/sulfamethoxazole may, in addition, be recommended. There is concern related to the presence of pus or previous MRSA infections. Elevating the infected area may be useful, as may pain killers.Potential complications include abscess formation. Around 95% of people are better after 7 to 10 days of treatment. Those with diabetes, however, often have worse outcomes. Cellulitis occurred in about 21.2 million people in 2015. In the United States about 2 of every 1,000 people per year have a case affecting the lower leg. Cellulitis in 2015 resulted in about 16,900 deaths worldwide. In the United Kingdom, cellulitis was the reason for 1.6% of admissions to a hospital. Signs and symptoms
The typical signs and symptoms of cellulitis are an area that is red, hot, and painful. The photos shown here are of mild to moderate cases and are not representative of the earlier stages of the condition. Complications
Potential complications may include abscess formation, fasciitis, and sepsis. Causes
Cellulitis is caused by bacteria that enter and infect the tissue through breaks in the skin. Group A Streptococcus and Staphylococcus are the most common causes of the infection and may be found on the skin as normal flora in healthy individuals.About 80% of cases of Ludwigs angina, or cellulitis of the submandibular space, are caused by dental infections. Mixed infections, due to both aerobes and anaerobes, are commonly associated with this type of cellulitis.