SKIN AND SOFT TISSUE INFECTIONS
ErysipelasErysipelas is a more acute and inflamed variant of cellulitis. Although erysipelas is often described as distinct from cellulitis, the differences can be subjective. It is usually caused by group A streptococci and commonly occurs on the lower legs or the face. Erysipelas is redder, more sharply demarcated, and more superficial than typical cellulitis. Lymphatic streaking and systemic symptoms are common. Because erysipelas is more superficial, edema may be less prominent. Repeated episodes of erysipelas can lead to permanent lymphatic damage and chronic stasis.Some clinicians use penicillin as the drug of choice for erysipelas. Other organisms, especially S. aureus, may cause more than 20% of cases of erysipelas and these bacteria are often resistant to penicillin. Unless streptococcal infection has been confirmed by culture, many clinicians use a broader spectrum antibiotic to cover S. aureus as well.
Blistering Distal DactylitisBlistering distal dactylitis is a superficial infection of the anterior fat pad of the distal fingers. It is most commonly caused by group A beta-hemolytic streptococci. A painful vesicle or pustule forms in the skin adjacent to the nail bed. These pustules do not tend to protrude like those elsewhere on the body. They should be promptly incised and drained, followed by a 10-day course of antibiotics.
Perianal CellulitisPerianal cellulitis is another form of cellulitis caused by group A beta-hemolytic streptococci. It occurs most commonly in children. Patients may present with perirectal itching, rectal pain, or blood-streaked stools. Systemic symptoms are uncommon. On examination, marked circumferential erythema is noted extending as far as 3 cm from the anus. Because recurrences are common, culture should be performed before and after treatment with a 10-day course of oral antibiotics.
Pseudomonas CellulitisPseudomonas aeruginosa typically causes infections in the warm, moist areas that it colonizes: feet, nail beds (green nail), skin folds, foreskin (balanitis), ear canals, and burn sites. P. aeruginosa will not grow if normal, dry skin is inoculated.Pseudomonas infection is characterized by dusky red skin, blue-green Purulence, and a fruity odor. Pseudomonas also fluoresces green-white under a Wood’s lamp because it produces a compound called pyoverdin. Neglected lesions can become eroded and even necrotic.Localized infection can be treated with 5% acetic acid compresses for 20 minutes, four times daily until resolution. For Pseudomonas balanitis, topical mercurochrome twice daily is effective. These infections can also be treated with systemic first- or second-generation fluoroquinolones.*109/348/5*
