Soft Tissue Infections

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Rosacea Free Forever Cure By Laura Taylor

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Erysipelas is caused exclusively by S. pyogenes and is characterized by the abrupt onset of fiery-red swelling of the face or extremities.17 Distinctive features are well-defined margins, particularly along the nasolabial fold; a scarlet or salmon-red color; rapid progression; and intense pain. Flaccid bullae filled with clear fluid may develop during the second to third day of illness, yet extension to deeper soft tissues, bacteremia, and shock occur only rarely. Surgical debridement is rarely required and treatment with penicillin is very effective. Swelling may progress despite treatment, though fever, pain, and intense redness diminish usually within 24 to 48 hours. Desquamation of the involved skin occurs 5 to 10 days into the illness and scarring of the skin does not occur. Infants and elderly adults are most commonly afflicted. Erysipelas has become less severe since the early 1900s even before antibiotic treatment became available.

Streptococcal Pyoderma (Impetigo Contagiosa)

The thick, crusted skin lesions of streptococcal pyoderma frequently have a golden-brown color resembling dried serum.17 Children between 2 and 5 years of age are most commonly infected. Epidemics occur throughout the year in tropical areas or during the summer months in more temperate climates and are usually associated with poor hygiene. Initially, colonization of the unbroken skin occurs either exogenously from patients with impetiginous lesions or endogenously by contamination of the skin with oropharyngeal organisms. Development of impetiginous lesions requires 10 to 14 days and is initiated by minor trauma such as an abrasion or insect bite, which facilitates intradermal inoculation. Patients with impetigo should receive penicillin, particularly when numerous sites of the skin are involved, though treatment does not prevent poststreptococcal glomerulonephritis. Topical treatment with an agent effective against gram-positive bacteria, such as bacitracin or mupirocin, is also effective. About 50% of cases of impetigo currently are caused by S. aureus.


GAS may invade the epidermis and subcutaneous tissues, resulting in local swelling, erythema, and pain.17 The skin becomes indurated and, in contrast to erysipelas, is a pinkish color. Patients with lymphedema secondary to lymphoma, filariasis, or surgical node dissection (mastectomy, carcinoma of the prostate, etc.) are predisposed to development of GAS cellulitis, as are those with chronic venous stasis and superficial dermatophyte infection of the toes. Saphenous vein donor site cellulitis may be due to group A, C, or G streptococci. Cellulitis associated with a primary focus (e.g., an abscess or boil) is more likely caused by S. aureus. Aspiration of the leading-edge and punch biopsy yield a causative organism in 15% and 40% of cases, respectively. Patients respond quickly to penicillin, though in some cases where staphylococcus is of concern, nafcillin or oxacillin may be a better choice, or one may need cover for methicillin-resistant S. aureus (MRSA) infection (discussed later in this chapter). If bluish or violet discoloration develops or if bullae become apparent, a deeper infection such as necrotizing fasciitis or myositis should be considered (see Necrotizing Fasciitis). Particularly when such patients demonstrate systemic toxicity, a serum creatine phosphokinase level should be obtained and, if elevated, prompt surgical inspection and debridement should be performed.


Cutaneous infection with bright red streaks ascending proximally is most commonly associated with GAS, though groups C and G have also been implicated. Prompt antibiotic treatment is mandatory because bacteremia and systemic toxicity develop rapidly once infected lymphatic fluid reaches the thoracic ducts.

Necrotizing Fasciitis

Necrotizing fasciitis, originally called streptococcal gangrene, is a deep-seated infection of the subcutaneous tissue that results in progressive destruction of fascia and fat but may spare the skin itself.17 Within the first 24 hours, swelling, heat, erythema, and tenderness develop and rapidly spread proximally and distally from the original focus. During the next 24 hours, the erythema darkens, changing from red to purple to blue, forming blisters and bullae that contain clear, yellow fluid.18 The purple areas become frankly gangrenous and extensive necrosis of the subcutaneous tissue ensues. Patients become increasingly toxic and develop shock and multiorgan failure. In the past, aggressive fasciotomy and debridement and application of Dakin's solution topically achieved mortality rates as low as 20%, even before antibiotics were available. The increased severity of necrotizing fasciitis that has occurred among recent cases of Strep TSS relative to shock, multiorgan failure, and mortality could be due to the increased virulence of GAS itself.

Myositis and Myonecrosis

Historically, streptococcal myositis has been an extremely uncommon GAS infection, and only 21 cases were documented from 1900 to 1985.19 Recently, an increased prevalence of GAS myositis has been reported in the United States, Norway, and Sweden.5,6,20 Translocation of GAS from an asymptomatic infection of the pharynx to the muscle site must occur hematogenously because penetrating trauma is not usually a major factor. Further, most patients have not reported symptomatic pharyngitis or tonsillitis. Severe pain at the site of infection may be the only presenting symptom; swelling and erythema may be the only signs of infection. Muscle compart-mental syndromes may develop rapidly In most cases a single muscle group is involved; however, because patients frequently have bacteremia, there may be other sites of myositis or abscess. Distinguishing streptococcal myositis from spontaneous gas gangrene caused by C. perfringens or C. septicum may be difficult, although the presence of crepitus or gas in the tissue would favor a diagnosis of clostridial infection. Myositis is easily distinguished from necrotizing fasciitis anatomically by means of surgical exploration or incisional biopsy, though clinical features of both conditions overlap and 30% to 40% of patients may have both. Though soft tissue radiography, computed tomography (CT), and magnetic resonance imaging (MRI) may be useful in localizing the site of infection, these generally show only edema or soft tissue swelling and do not distinguish myonecrosis or myositis from soft tissue damage due to blunt trauma. Increasing quantities of muscle enzymes in the serum may provide a useful clinical clue of deep infection. In published reports, the case-fatality rate of necrotizing fasciitis is between 20% and 50%, whereas that of GAS myositis is between 80% and 100%. Aggressive surgical debridement is of extreme importance because of the poor efficacy of penicillin described in human cases as well as in experimental strepto-coccal models of myositis (see Treatment).

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