Gram-negative folliculitis most often develops as a superinfection in people who have undergone prolonged oral antibiotic therapy. It is characterized by pustules in the area of the nose. The pathogens in the superficial form of this infection are usually Klebsiella or Enterobacter species. A deep nodular or cystic form of Gram-negative folliculitis is caused by Proteus species and also tends to appear on the face.
Hot-tub folliculitis is a special form of Gram-negative folliculitis caused by Pseudomonas. It occurs within 6 h to 3 d after exposure to poorly maintained hot tubs. The trunk, buttocks, legs, and arms are sites of predilection. Mild constitutional symptoms, including fever and malaise, may accompany the cutaneous findings. Hot-tub folliculitis, which is generally a benign, self-limited condition, can progress to a serious illness in an immunocompromised host.
A furuncle is a deeper, more aggressive infection of a hair follicle or a cutaneous gland. These lesions range in size from 5 mm to 3 cm diameter and occur most commonly on hairy areas exposed to friction, trauma, or macerations (i.e., buttocks, face, neck, axillae, groin, thighs, upper back). Patients present with a painful, often fluctuant swelling. Pruritus, local tenderness, and erythema are often associated. As pus forms in the center of the lesion, the overlying skin becomes thin, the lesion becomes elevated, pain increases, and spontaneous drainage of pus ultimately occurs.
A carbuncle is a coalescent mass of deeply infected follicles or sebaceous glands with multiple interconnecting sinus tracts and cutaneous openings that drain pus ineffectively. Carbuncles usually occur in the thick skin on the back of the neck and the upper back. The lesions steadily worsen, with increasing pain, erythema, swelling, purulent drainage, and lateral enlargement. These lesions range from 3 to 10 cm in diameter. Fever and other systemic symptoms and signs are common.
Hairy areas of the body, particularly the beard, scalp, back, legs, and arms, are common site of involvement. The patient may live in a warm, damp climate. Persons with diabetes are particularly susceptible to folliculitis. Other predisposing conditions include hot and humid weather, improper hygiene, tight clothing, occlusion caused by oil-based cosmetics or sunscreen products, and occupational exposure to irritating substances such as cooking oils, greases, or solvents.
S. aureus cause most cases of folliculitis. Micrococcus, Pityrosporum, and Demodex organisms are organisms that normally colonize skin but may become pathogens in the immunocompromised patient (26). Gram-negative folliculitis is caused by Klebsiella, Enterobacter, and Proteus species and may occur as a superinfection in acne vulgaris patients treated with long-term antibiotic therapy (27). As previously noted, hot-tub folliculitis is a special form of folliculitis caused by Pseudomonas aeruginosa.
Folliculitis is often treated with frequent use of soap and water and the application of topical antibiotic agents such as mupirocin, clindamycin, erythromycin, or baci-tracin. Occasionally, the addition of a systemic antistaphylococcal agent is required. Furuncles and carbuncles often require incision and drainage. Along with mild cleans ing and warm compresses, antibiotic therapy should be attempted if the furuncle is not yet fluctuant, if there is evidence of surrounding cellulitis lymphadenitis, or if the lesion is on the face. Semisynthetic penicillins or first-generation cephalosporins are the drugs of choice.
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