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

Int J Dermatol. 1999 Apr;38(4):270-4. doi: 10.1046/j.1365-4362.1999.00688.x.


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.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Complement C3 / metabolism
  • Complement C4 / metabolism
  • Female
  • Folliculitis / complications*
  • Folliculitis / drug therapy
  • Folliculitis / immunology
  • Follow-Up Studies
  • Gram-Negative Bacteria / drug effects
  • Gram-Negative Bacteria / isolation & purification*
  • Gram-Negative Bacterial Infections / complications*
  • Gram-Negative Bacterial Infections / drug therapy
  • Gram-Negative Bacterial Infections / microbiology
  • Humans
  • Immunoglobulins / blood
  • Isotretinoin / therapeutic use
  • Keratolytic Agents / therapeutic use
  • Male
  • Middle Aged
  • Skin / drug effects
  • Skin / microbiology
  • Skin / pathology
  • Treatment Outcome
  • alpha 1-Antitrypsin / metabolism


  • Complement C3
  • Complement C4
  • Immunoglobulins
  • Keratolytic Agents
  • alpha 1-Antitrypsin
  • Isotretinoin