Intertrigo e infecções secundárias da pele

Etiology and Predisposing Factors
Intertrigo is primarily caused by skin-on-skin friction and is characterized by initial mild erythema that may progress to a more intense inflammation with erosions, oozing, exudation, maceration, and crusting. Intertrigo is facilitated by moisture trapped in deep skinfolds where air circulation is limited. The condition is particularly common in obese patients with diabetes who are exposed to high heat and humidity, but it can occur in anyone. Other predisposing risk factors include urinary and fecal incontinence, hyperhidrosis, poor hygiene, and malnutrition. Toe interweb intertrigo may be associated with closed-toe or tight-fitting shoes and commonly affects persons participating in athletic, occupational, or recreational activities. Infants are at high risk for intertrigo because they have short necks, relative chubbiness, and flexed posture. Drooling also can facilitate intertrigo in infants. Persons with prominent skinfolds on either side of the chin are at a high risk for intertrigo.

Secondary Skin Infections
The moist, damaged skin associated with intertrigo is a fertile breeding ground for various microorganisms, and secondary cutaneous infections commonly are observed in these areas. Bacterial proliferation may be associated with keratinocytic necrosis. Staphylococcus aureus may present alone or with group A beta-hemolytic streptococcus (GABHS). Pseudomonas aeruginosa, Proteus mirabilis, or Proteus vulgaris also may occur alone or simultaneously.

A variety of fungi may exacerbate intertrigo, including yeasts, molds, and dermatophytes. Candida is the fungus most commonly associated with intertrigo. The inflammation may begin as a dermatophyte infection, which can damage the stratum corneum and encourage the proliferation of other, usually antibiotic-resistant bacteria.

Dermatophytes (e.g., Trichophytonrubrum, Trichophyton mentagrophytes, Epidermophyton floccosum) commonly complicate interdigital intertrigo. Gram-positive and gram-negative bacteria also can worsen the effects of interdigital intertrigo. Gram-negative toe web infections often are caused by P. aeruginosa combined with other gram-negative bacteria such as Moraxella, Alcaligenes, Acinetobacter, and Erwinia. However, gram-negative and gram-positive infections occasionally occur simultaneously in interdigital areas. Gram-positive infections usually are caused by S. aureus and GABHS and occasionally are caused by Staphylococcus saprophyticus or other coagulase-negative staphylococci. Dermatophytes and bacterial infections often occur together in interdigital areas. Yeasts also are commonly found at the site of interdigital intertrigo. Sometimes seborrheic dermatitis is located in the folds. Whether Malassezia-complicated intertrigo is a distinct entity or a type of seborrheic dermatitis remains unclear.

Cutaneous erythrasma may complicate intertrigo of interweb areas, intergluteal and crural folds, axillae, or inframammary regions. Erythrasma is a bacterial infection caused by Corynebacterium minutissimum. Cutaneous erythrasma presents as small, red-brown macules that may coalesce into larger patches with sharp borders. These lesions often are asymptomatic but may be pruritic in some instances.

Clinical Manifestations
Intertrigo is characterized primarily by mild erythema that initially presents as red plaques, almost in a mirror image, on each side of the skinfold. The erythema may progress to more intense inflammation with erosions, oozing, fissures, exudation, maceration, and crusting. Patients may present with itching, burning, and pain in the affected areas. More prominent inflammation could be a sign of secondary infection. Well-demarcated red, weeping intertrigo may be mechanical or may be a sign of secondary GABHS infection. Streptococcal intertrigo may be difficult to recognize in children when it presents as an intense erythema with maceration on the neck folds, axillae, or inguinal regions; it is characterized by a foul odor and an absence of satellite lesions. Candidal intertrigo usually presents as typical satellite papules or pustules. Toe web intertrigo usually is associated with a burning sensation between the toes, often with maceration. Toe web intertrigo may be simple, mild, and asymptomatic, but it also can be seen as intense erythema and desquamation, which sometimes is erosive, malodorous, and macerated. Patients also may have profuse or purulent discharge and be unable to ambulate. In severe examples, patients may have a purulent discharge with edema and intense erythema of tissues surrounding the infected area. Patients with severe toe web intertrigo who are overweight or who have diabetes are at a higher risk for cellulitis. Patients with advanced gram-negative infections may have green discoloration at the infection site. Erythematous desquamating infection may be more chronic than the acute form and may present with a painful, exudative, macerating inflammation that causes functional disability of the feet.

Diagnosis
Diagnosis of intertrigo and its secondary complications often is clear and is generally based on clinical manifestations. The characteristics of intertriginous lesions (e.g., erosions, vesicles, pustules, nodules, papules, plaques, macules) can indicate the type of disorder present.2 Skin biopsy specimens usually are not required because the histology of intertrigo shows no characteristic features. If secondary bacterial infections are suspected, culture with sensitivities should be performed. A Wood’s light examination may identify a Pseudomonas or erythrasma infection more quickly than would a culture. The Wood’s light characteristically shows a green fluorescence with Pseudomonas infection and a coral-red fluorescence with erythrasma. Potassium hydroxide cytologic examination is helpful in diagnosing secondary fungal infections. Hyphae should be apparent with dermatophytes, whereas pseudohyphae should appear if candidiasis is present.8 A mycologic culture may help identify the specific species.

Differential Diagnosis
Patients who do not respond to therapy should be reexamined for another primary or secondary dermatologic condition that may resemble intertrigo. Seborrheic dermatitis and psoriasis vulgaris inversa may have presentations similar to intertrigo. Seborrheic dermatitis may involve the axillae or inguinal regions or the scalp. Psoriasiform lesions elsewhere on the body or pitting of the nails also may distinguish psoriasis from intertrigo. Rarely, skin biopsy specimens are needed to distinguish less common skin diseases from intertrigo. Atopic dermatitis, primary irritant contact dermatitis, allergic contact dermatitis, scabies, and pemphigus vegetans sometimes are mistakenly diagnosed as intertrigo because these conditions also may involve skinfolds. Unusual intertriginous involvement also may represent a localized drug eruption. The presence of widespread macular eruptions and eroded lesions in the inguinal folds, with negative cultures, may be an early marker of primary HIV-1 infection.