Bacteriologic and immunologic aspects of Gram-negative folliculitis: a study of 46 patients

Background Gram-negative folliculitis is an infection with Gram-negative rods that most often occurs as a complication of prolonged broad-spectrum antibiotic therapy in patients suffering from acne and rosacea. Methods The bacteriologic and immunologic findings are reported in 46 patients, 39 men and 7 women, aged 16-79 (median, 28) years, with Gram-negative folliculitis. Hypersensitivity reactions to various microbial recall antigens as well as granulocyte functions were evaluated. Quantitative measurements of serum levels of immunoglobulin M, G, A, and E, total complement activity, complement factors C3 and C4, and alpha-1-antitrypsin were performed. Results The Gram-negative organisms most frequently cultivated from nares, facial skin, and pustules were Klebsiella spp., Escherichia coli, Enterobacter spp., and Proteus spp. In all patients, deviations of one or more immune parameters were detected, including lowered serum concentrations of immunoglobulin M and alpha-1-antitrypsin, and elevated levels of immunoglobulin E. The humoral and cellular parameters were not influenced by isotretinoin therapy of Gram-negative folliculitis. Conclusions These findings suggest that Gram-negative folliculitis is not only a complication of long-lasting antibiotic treatment of acne and rosacea, but might be an entity of its own. Immunologic factors may play a critical role in the pathogenesis of Gram-negative folliculitis.