26 Soft Tissue Infections

Soft tissue infections range in severity from minor infec- obacter, Pseudomonas, Serratia, and Bacteroides, can tions of the epidermis, which are treated medically, to cause necrotizing infections, although they do so much major necrotizing infections, which can cause death if not less frequently. Nearly all necrotizing infections are treated immediately. is a superficial spreading polymicrobial in nature. Risk factors for developing a bacterial infection of the skin and subcutaneous tissue. It necrotizing infection are diabetes mellitus, , mal- manifests with erythema, warmth, tenderness, and edema. nutrition, alcoholism, peripheral vascular disease, chronic The organisms most often are responsible for cellulitis lymphocytic leukemia, steroid use, renal failure, cirrhosis, are group A and Staphylococcus aureus. and autoimmune deficiencies. Most cases of cellulitis are treated with ; Treatment for necrotizing infections includes early however, when the infection is deeply seeded, an recognition, broad-spectrum antibiotics, and aggressive forms, which requires surgical . surgical debridement. Patients should be admitted to is the infection or inflammation of a hair fol- the intensive care unit for aggressive fluid replacement licle, often caused by Staphylococcus; however, Gram- caused by the renal failure that develops due to asso- negative organisms can cause them also. These infections ciated septic shock. Debridement should remove all often resolve without intervention. If folliculitis pro- infected tissue, with additional debridements and rea- gresses to the development of a fluctuant nodule, it is ssessments in the operating room as needed. The pos- termed a furuncle. The small abscess usually sponta- sible benefit of hyperbaric oxygen treatment is debated; neously ruptures and resolves. Drainage can be acceler- however, there are no definitive data showing benefit. ated with warm soaks. If the infection is deep with is another soft tissue infec- multiple draining cutaneous sinuses, it is called a carbun- tion often encountered by general surgeons. This condi- cle. Treatment of a involves either incision and tion is caused by a defect of the terminal follicular drainage or a wide local excision of the infected tissue epithelium of the apocrine glands, which leads to block- and the associated sinus tracts. age of the gland that causes infection.This occurs in areas Necrotizing soft tissue infections spread rapidly, where apocrine glands are most numerous, including the destroy tissue, and can be associated with septic shock. axillary, inguinal, and perianal regions of the body. There Classification of these infections is based on the tissue is a genetic component to hidradenitis suppurativa. The planes affected, extent of invasion, location, and the expression of the involved gene is under hormonal influ- causative pathogen. The most common type is necrotiz- ence, so it manifests as patients reach puberty.The disease ing fasciitis, which invades along the fascia deep to the process includes formation of with repeated adipose tissue. Necrotizing myositis is less common, draining sinuses. This leads to scarring and pain. The involves the muscle, and spreads into the surrounding soft treatment for an acute abscess is application of a warm tissues. in specific locations has sep- compress, antibiotics, and drainage. Improved hygiene arate names, such as Fournier’s when there is helps prevent recurrences; however, many patients necrotizing fasciitis in the perineum. Despite the differ- develop chronic hidradenitis, which requires wide exci- ent names, the disease process is the same. The most sion of the affected area and skin grafting if the area is common causative pathogens in necrotizing fasciitis are extensive. Gram-positive organisms such as group A Streptococcus, is an infection that begins with Enterococcus, Staphylococcus aureus, and . obstruction of a hair follicle and the associated piloseba- Gram-negative organisms, such as Escherichia coli, Enter- ceous unit in the gluteal cleft. A localized folliculitis

67 68 Part VI. ICU and Trauma occurs, and it spreads and produces an abscess. The ommended so that diagnosis and comprehensive medical abscess often drains spontaneously, producing a sinus treatment can be started. Treatment consists primarily of tract located just off the midline. The sinus tract is lined systemic steroids and cyclosporine. In cases of slow with granulation tissue. Over time, the tract epithelializes. wound healing, local wound care and skin grafting may Hair and debris enter the tract and cause further foreign be needed. body reactions. Infected pilonidal occur primarily in Staphylococcal scalded skin syndrome manifests clini- young adults, with males being affected four times as cally with erythema of the skin, bullae formation, and often as females.Treatment for an acute pilonidal abscess skin loss. It is caused by an exotoxin produced by Staphy- is incision and drainage without antibiotics. Because the lococcus infections of the nasopharynx or middle ear (in recurrence rate is high, the chronic sinus tract should be children).The diagnosis is made when a skin biopsy spec- treated by local excision and closure, by wide excision imen demonstrates a cleavage plane in the granular layer with marsupialization or flap closure, or by tract curet- of the epidermis. This lesion can easily be confused clin- tage. Nonsurgical options include shaving the gluteal cleft ically with toxic epidermal necrolysis because they have and careful perianal hygiene; however, these have much very similar appearances. Toxic epidermal necrolysis is greater recurrence rates compared with surgical excision. caused by an immunologic reaction to drugs such as sul- One rare but possible complication of pilonidal disease fonamides, phenytoin, barbiturates, and tetracycline. It is is the development of squamous cell carcinoma arising not due to an infectious process. A skin biopsy specimen from the sinus tract. of toxic epidermal necrolysis shows a cleavage plane at gangrenosum is a rare inflammatory condi- the dermoepidermal junction. Another name for toxic tion of the soft tissue. Although it is not a true infection, epidermal necrolysis, when less than 10% of the patient’s it is sometimes confused with one. The lesions caused by epidermis is detached, is Stevens-Johnson syndrome. pyoderma gangrenosum are rapidly enlarging necrotic Patients with toxic epidermal necrolysis can also have skin lesions with an indeterminate border and surround- respiratory and gastrointestinal symptoms caused by the ing erythema. More than half of the patients with these sloughing of epithelium along these tracts. Both types of lesions have an underlying systemic disease, such as epidermal conditions, toxic epidermal necrolysis and inflammatory bowel disease, rheumatoid arthritis, a staphylococcal scalded skin syndrome, should be treated hematologic malignancy, or monoclonal immunoglobulin like second-degree burns with fluid resuscitation and A gammopathy. Because of the incidence of other serious local wound care with temporary coverage with a biologic medical conditions, extensive medical workups are rec- dressing for protection while the epidermis regenerates.