Gram-negative folliculitis is a specific form of acne that occurs with prolonged use of antibiotics, most commonly in cases of acne vulgaris or rosacea. ICD-10 code L73.8.
Gram-negative folliculitis is seen in 4-5% of patients receiving prolonged antibiotic therapy for acne vulgaris and rosacea, and less frequently in other conditions (e.g., staphylococcal skin infections) and with prolonged use of topical antibacterial agents. However, its incidence is thought to be underestimated due to diagnostic errors and is more common in males.
This condition is characterized by replacement of the normal gram-positive skin and nasal mucosal flora by gram-negative microorganisms, primarily Enterobacteriaceae, and less commonly Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, Klebsiella, and Proteus mirabilis. Normally, Gram-negative bacteria make up less than 1% of the total bacterial population in the nasal mucosa, but in patients with Gram-negative folliculitis, Enterobacteriaceae make up approximately 4%. Gram-negative organisms require a moist environment for growth and reproduction, which is why they colonize areas of the skin with increased sebum production (seborrheic zones).
Initially, the sebaceous follicles around the nose and mouth are affected, and the disease may spread to other areas of the facial skin. Tetracyclines disrupt protein synthesis and human lymphocyte function, as well as neutrophil chemotaxis, increasing the risk of bacterial superinfection.
Several studies have identified alterations in the immune defenses of patients with acne and gram-negative folliculitis. In one study, patients had suppressed cell-mediated immunity, weak or absent delayed-type hypersensitivity responses, and decreased IgM concentrations. Low IgM levels may result in a decreased or absent response to enterobacterial O-antigens, increasing the likelihood of gram-negative infection. Alpha-1-antitrypsin deficiency is also a cofactor in the development of gram-negative folliculitis by inactivating neutrophil granulocytic protease.A typical patient with gram-negative folliculitis is a male over 18 years of age with oily seborrhea, perioral and perinasal papules and pustules, often with recurrent folliculitis on the hairy part of the head, on prolonged antibacterial therapy, and with an increase in gram-negative cultures when material from pustules and nasal mucosa is cultured. There are two types of gram-negative folliculitis:
Papulopustular type:
Characterized by abundant papular and pustular eruptions in seborrheic areas, primarily perioral and perinasal, although other sites are possible. It is seen in 80% of patients. It is commonly associated with Enterobacteriaceae, less commonly with Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, Klebsiella, and Citrobacter.
Nodular-cystic type:
Found in 20% of patients. Characterized by deep-seated nodules, abscesses, and fluctuating cysts from which organisms such as Proteus are cultured. The clinical presentation resembles conglobate acne, leading to diagnostic errors and the prescription of high-dose antibiotics, which may worsen the condition.
- Acne
- Bacterial Folliculitis
- Pseudomonal Folliculitis
- Pityrosporal Folliculitis
- Eosinophilic Folliculitis
Oral isotretinoin is considered the first-line therapy for gram-negative folliculitis. The effectiveness of isotretinoin is explained by its ability to reduce sebum secretion by 90%, which leads to drying of the skin and mucous membranes, creating an unfavorable environment for the growth and proliferation of gram-negative bacteria. Isotretinoin is prescribed at a dose of 0.5-1 mg/kg daily for 4-5 months, and higher doses above 2.0 mg/kg offer no advantages over lower doses. The optimal effective dose with the lowest relapse rate is 1 mg/kg.
Studies have shown that the efficacy of antibiotic therapy based on culture results is generally low. However, in some severe cases, concomitant administration of isotretinoin and antibiotics such as ampicillin (250 mg orally four times daily) or trimethoprim/sulfamethoxazole (80/400 mg orally four times daily) may be considered.