๐ ็ธฝ็ฎ้ ๏ฝ ๐ ่ฑๆๅๆ๏ผๆฌ็ฏ๏ผ ๏ฝ ๐ ๅฎๆด็ฟป่ญฏ ๏ฝ โญ ็ฒพ่ฏ็ญ่จ
Gram-negative folliculitis
Gram-negative folliculitis
Clinical features This is an uncommon complication of long-term broad-spectrum antibiotic therapy for acne or rosacea.1โ6 Growth of Gram-negative organisms in the anterior nasal region has been observed to occur in 85% of patients. Up to 4% of such patients may present with suppurative folliculitis, either as papules and pustules emanating from the anterior nasal region or, less often, with acne conglobata-like nodules.1,3,4 The former most commonly are due to Enterobacter, Klebsiella, or Escherichia coli, whereas the latter results from Proteus infection.7
Dry shaving worsens the condition.2 The shaft penetrates directly through the adjacent follicular epithelium into the superficial dermis. Hair in individuals with black skin is elliptical in shape and, when cut, often has a sharp pointed end.1 In addition, the majority of these individuals have helical or spiral hair and as the follicles are curved in the dermis with the hair shaft leaving the skin at an oblique angle, the risk of hair reentering the skin after close shaving is very high.9
Early lesions are characterized by a neutrophilic response, and intraepidermal abscesses are sometimes seen.8 This is later replaced by a foreign body granulomatous reaction to hair shafts. In those lesions that have developed following a transepidermal route, the hair may be ensheathed by an epidermal downgrowth. Chronic lesions are scarred and keloid formation is not uncommon. Scar-associated noncaseating granulomata in a patient with sarcoidosis have been documented.10
Pathogenesis and histologic features Long-term antibiotic therapy results in bacterial colonization of the anterior nostrils.1โ4 The presence of low serum IgM and ฮฑ1-antitrypsin levels and raised serum IgE suggests that immune abnormalities may also be of importance.8
Diagnosis is often difficult as bacteria may be scanty and multiple cultures are often necessary.1,4
Access ExpertConsult.com for the complete list of references