Cellulitis

Cellulitis is "an acute, diffuse, and suppurative inflammation of loose connective tissue, particularly the deep subcutaneous tissues, and sometimes muscle, which is most commonly seen as a result of infection of a wound, ulcer, or other skin lesions." The condition has been known from antiquity; generations of medical students learned its signs as rubor, tumor, calor, dolor or "reddened, swollen, warm to the touch, and painful." The presence of broken skin in the inflamed area is a further warning, but there may be no obvious wound.

The most common organisms are:

• Staphylococcus aureus
• Streptococcus pyogenes (group A strept)

One study found that about 75% of cases are due to Streptococcus pyogenes and that beta-lactam antibiotics ineffective against MRSA are effective for cellulitis.

Differential diagnosis to rule out life-threatening conditions, such as deep venous thrombosis, compartment syndrome and gangrene, is essential; a presentation of the common signs of cellulitis needs urgent, if not emergent, evaluation.

Treatment

According to the 2005 clinical practice guidelines, which state that staphylococcus aureus is very uncommon: "Suitable agents include dicloxacillin, cephalexin, clindamycin, or erythromycin, unless streptococci or staphylococci resistant to these agents are common in the community."

Cellulitis is sometimes self-limiting, but will sometimes need antibiotic therapy and sometimes surgical debridement and drainage.

If levofloxacin is used for treatment, 5 days is as effective as 10 days. However, levoflaxacin is ineffective against methicillin-resistant Staphylococcus aureus.