Understanding the Causes of Skin Folliculitis 毛囊炎
Skin folliculitis is a common condition characterized by inflammation of hair follicles, typically caused by bacterial, fungal, or viral infections, as well as factors like friction, poor hygiene, and certain medical conditions. Other contributing factors include ingrown hairs, hot and humid environments, tight clothing, and exposure to irritants or allergens. Inflammation may be superficial or deep in the hair follicle. Recognizing the diverse causes of folliculitis is essential for accurate diagnosis and effective treatment.
1. Bacterial Infection: Staphylococcus aureus is the most common bacterium responsible for folliculitis. When bacteria invade hair follicles, they can cause inflammation and infection, leading to folliculitis. Other bacteria, such as Pseudomonas aeruginosa, can also cause folliculitis, especially in hot tubs or pools.
2. Fungal Infection: Fungi like Malassezia species can infect hair follicles, particularly in warm and humid environments. Fungal folliculitis often presents as itchy, inflamed bumps and may require antifungal treatment for resolution.
3. Viral Infection: Viruses such as herpes simplex virus or varicella-zoster virus can lead to folliculitis in some cases. These infections typically present with grouped vesicles or blisters around affected follicles.
4. Pseudofolliculitis Barbae (Ingrown Hairs): Commonly known as razor bumps, this condition occurs when shaved hairs grow back into the skin, causing inflammation. It’s more common in individuals with curly hair and can be exacerbated by improper shaving techniques.
5. Hot and Humid Environments: Warm and humid climates can promote the growth of bacteria and fungi on the skin, increasing the risk of folliculitis. Sweat can also contribute to follicle irritation and inflammation.
6. Friction from Clothing: Tight clothing, synthetic fabrics, or rough materials can rub against the skin and cause irritation, leading to folliculitis. This is especially common in areas where clothing fits tightly against the body.
7. Excessive Oil Production: Overproduction of sebum (skin oil) can clog hair follicles, providing a breeding ground for bacteria and leading to folliculitis. Individuals with oily skin or certain hormonal imbalances may be more prone to this type of folliculitis.
8. Poor Hygiene: Inadequate hygiene practices, such as infrequent washing or not properly cleansing after sweating, can lead to the buildup of dirt, oil, and bacteria on the skin, increasing the risk of folliculitis.
9. Use of Steroids or Immunomodulatory Medications: Prolonged use of corticosteroids or other immunosuppressive medications can weaken the skin’s immune response, making it more susceptible to infections, including folliculitis.
10. Chemotherapy and Radiation Therapy: Cancer treatments such as chemotherapy and radiation therapy can compromise the immune system, increasing the risk of folliculitis and other skin infections.
11. Contact Dermatitis: Exposure to irritants or allergens in skincare products, detergents, or chemicals can cause contact dermatitis, leading to folliculitis as a secondary reaction.
12. Insect Bites and Parasitic Infections: Insect bites and parasitic infestations such as scabies or lice can introduce bacteria into hair follicles, triggering folliculitis due to scratching and skin irritation.
13. Occlusion: Tight clothing, bandages, or occlusive skincare products can trap sweat, bacteria, and debris against the skin, leading to folliculitis.
14. Underlying Medical Conditions: Conditions such as diabetes, HIV/AIDS, or autoimmune diseases can weaken the immune system, increasing the susceptibility to folliculitis.
| Superficial folliculitis | Deep folliculitis |
| Staphylococcal folliculitis | Furuncle and carbuncle |
| Pseudofolliculitis barbae (from shaving) | Sycosis (inflammation of entire depth of follicle) |
| Superficial fungal infections (dermatophytes) |
Sycosis (beard area): sycosis barbae, bacterial or fungal |
| Cutaneous candidiasis (pustules also occur outside the hair follicle) | Sycosis (scalp): bacterial |
| Acne vulgaris | Acne vulgaris, cystic |
| Acne, mechanically or chemically induced | Gram-negative acne |
| Steroid acne after withdrawal of topical steroids | Pseudomonas folliculitis |
| Keratosis pilaris | Dermatophyte fungal infections |
.
Reference
Thomas P. Habif. Clinical Dermatology:A Color Guide to Diagnosis and Therapy, 6th Edition – April 23, 2015. Elsevier. P345
