Infectious Folliculitis

Etiology and Risk Factors

Infectious folliculitis occurs due to inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the superficial or deep portion of the hair follicle Hair follicle A tube-like invagination of the epidermis from which the hair shaft develops and into which sebaceous glands open. The hair follicle is lined by a cellular inner and outer root sheath of epidermal origin and is invested with a fibrous sheath derived from the dermis. Follicles of very long hairs extend into the subcutaneous layer of tissue under the skin. Cowden Syndrome caused by an infectious agent (see table below).

Clinical Presentation and Diagnosis

Clinical presentation

• Lesions appear on hair-bearing skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions anywhere on the body
• 2 types of folliculitis: superficial and deep
• Superficial:
  • Pruritus Pruritus An intense itching sensation that produces the urge to rub or scratch the skin to obtain relief. Atopic Dermatitis (Eczema)
  • Follicular pustules
  • Erythematous, tender papules
  • Scarring Scarring Inflammation from prior or recurrent folliculitis eruptions
  • Pseudofolliculitis barbae presents as firm, tender, hyperpigmented papules and pustules, most commonly on the neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess and face in men and groin Groin The external junctural region between the lower part of the abdomen and the thigh. Male Genitourinary Examination area in women.
• Deep:
  • Furuncle (“boil”): a purulent nodule Nodule Chalazion arising from folliculitis that affects deeper layers of skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions, including subcutaneous tissue Subcutaneous tissue Loose connective tissue lying under the dermis, which binds skin loosely to subjacent tissues. It may contain a pad of adipocytes, which vary in number according to the area of the body and vary in size according to the nutritional state. Soft Tissue Abscess
  • Carbuncle: the coalescence of several furuncles into a single mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast
  • Furuncles and carbuncles may lead to a skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease. 
    • Accumulation of pus and necrotic tissue in the dermis Dermis A layer of vascularized connective tissue underneath the epidermis. The surface of the dermis contains innervated papillae. Embedded in or beneath the dermis are sweat glands; hair follicles; and sebaceous glands. Skin: Structure and Functions and deeper skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions layers
    • Management requires incision and drainage Incision And Drainage Chalazion.

Diagnosis

• Clinical, with no diagnostic tests Diagnostic tests Diagnostic tests are important aspects in making a diagnosis. Some of the most important epidemiological values of diagnostic tests include sensitivity and specificity, false positives and false negatives, positive and negative predictive values, likelihood ratios, and pre-test and post-test probabilities. Epidemiological Values of Diagnostic Tests required
• However, if the diagnosis is unclear:
  • Gram stain Gram stain Klebsiella and culture of the pus to identify bacterial pathogen
  • KOH preparation KOH preparation Primary Skin Lesions can confirm fungal folliculitis Fungal folliculitis Dermatophytes/Tinea Infections.
  • Viral culture Viral culture West Nile Virus or polymerase chain reaction Polymerase chain reaction Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR) ( PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR)) should be used to confirm herpes folliculitis, if suspected.

Management

Management consists mostly of supportive measures:

• Good skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions hygiene
• Warm compresses Warm Compresses Chalazion
• Antibacterial Antibacterial Penicillins soap

Antibiotic therapy is guided by the suspected or known causative organism:

• Gram-positive Gram-Positive Penicillins bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology
  • Mild cases: often resolve spontaneously; consider topical mupirocin or topical clindamycin Clindamycin An antibacterial agent that is a semisynthetic analog of lincomycin. Lincosamides
  • Severe cases: oral antibiotics (cephalexin, dicloxacillin Dicloxacillin One of the penicillins which is resistant to penicillinase. Penicillins)
  • If MRSA MRSA A strain of Staphylococcus aureus that is non-susceptible to the action of methicillin. The mechanism of resistance usually involves modification of normal or the presence of acquired penicillin binding proteins. Staphylococcus positive, 7–10-day course (occasionally > 2 weeks) of oral trimethoprim Trimethoprim The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. Sulfonamides and Trimethoprim/ sulfamethoxazole Sulfamethoxazole A bacteriostatic antibacterial agent that interferes with folic acid synthesis in susceptible bacteria. Its broad spectrum of activity has been limited by the development of resistance. Sulfonamides and Trimethoprim, clindamycin Clindamycin An antibacterial agent that is a semisynthetic analog of lincomycin. Lincosamides, or doxycycline
• Gram-negative bacteria gram-negative bacteria Bacteria which lose crystal violet stain but are stained pink when treated by gram’s method. Bacteriology
  • Mild cases: often resolve spontaneously
  • Severe cases/ immunocompromised patient Immunocompromised patient A human or animal whose immunologic mechanism is deficient because of an immunodeficiency disorder or other disease or as the result of the administration of immunosuppressive drugs or radiation. Herpes Zoster (Shingles): oral antibiotics (oral ciprofloxacin Ciprofloxacin A broad-spectrum antimicrobial carboxyfluoroquinoline. Fluoroquinolones or  trimethoprim Trimethoprim The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. Sulfonamides and Trimethoprim/ sulfamethoxazole Sulfamethoxazole A bacteriostatic antibacterial agent that interferes with folic acid synthesis in susceptible bacteria. Its broad spectrum of activity has been limited by the development of resistance. Sulfonamides and Trimethoprim)
• Fungal: requires systemic therapy with oral antifungal Antifungal Azoles agents ( itraconazole Itraconazole A triazole antifungal agent that inhibits cytochrome p-450-dependent enzymes required for ergosterol synthesis. Azoles or fluconazole Fluconazole Triazole antifungal agent that is used to treat oropharyngeal candidiasis and cryptococcal meningitis in aids. Azoles) 
• Viral: Herpes infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease may require oral acyclovir Acyclovir A guanosine analog that acts as an antimetabolite. Viruses are especially susceptible. Used especially against herpes. Herpes Zoster (Shingles), famciclovir Famciclovir An aminopurine derivative and prodrug of penciclovir which is a competitive inhibitor of herpes simplex 2 DNA polymerase. It is used to treat herpes simplex virus infection. Antivirals for Herpes Virus, or valacyclovir Valacyclovir A prodrug of acyclovir that is used in the treatment of herpes zoster and herpes simplex virus infection of the skin and mucous membranes, including genital herpes. Herpes Zoster (Shingles).

Differential Diagnosis

The following conditions can be confused with infectious folliculitis.

Predominantly on face and scalp

• Acne vulgaris Acne vulgaris Acne vulgaris, also known as acne, is a common disorder of the pilosebaceous units in adolescents and young adults. The condition occurs due to follicular hyperkeratinization, excess sebum production, follicular colonization by Cutibacterium acnes, and inflammation. Acne Vulgaris: chronic inflammatory disorder of the pilosebaceous unit that is is self-limiting Self-Limiting Meningitis in Children. Comedones Comedones Acne Vulgaris and a lack of pruritus Pruritus An intense itching sensation that produces the urge to rub or scratch the skin to obtain relief. Atopic Dermatitis (Eczema) favor acne vulgaris Acne vulgaris Acne vulgaris, also known as acne, is a common disorder of the pilosebaceous units in adolescents and young adults. The condition occurs due to follicular hyperkeratinization, excess sebum production, follicular colonization by Cutibacterium acnes, and inflammation. Acne Vulgaris over infectious folliculitis.
• Rosacea Rosacea Rosacea is a chronic inflammatory disease of the skin that is associated with capillary hyperreactivity. This condition is predominantly seen in middle-aged women, and is more common in fair-skinned patients. Rosacea (papulopustular type): inflammatory skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions disorder exacerbated by sunlight or alcohol; exhibits pustules, papules, and dilated vessels in an erythematous background
• Acne keloidalis Acne keloidalis A type of acneiform disorder in which secondary pyogenic infection in and around pilosebaceous structures ends in keloidal scarring. It manifests as persistent folliculitis of the back of the neck associated with occlusion of the follicular orifices. It is most often encountered in black or Asian men. Hypertrophic and Keloid Scars nuchae: a chronic, scarring Scarring Inflammation folliculitis that primarily affects males of African descent, with papules, pustules, and keloidal nodules on the posterior scalp
• Pseudofolliculitis barbae (“shaving rash Rash Rocky Mountain Spotted Fever”): inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation caused by hair penetrating interfollicular skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions after shaving (“ingrown hairs”), especially in individuals of African descent; can also occur anywhere hair is shaved or plucked, including axilla Axilla The axilla is a pyramid-shaped space located between the upper thorax and the arm. The axilla has a base, an apex, and 4 walls (anterior, medial, lateral, posterior). The base of the pyramid is made up of the axillary skin. The apex is the axillary inlet, located between the 1st rib, superior border of the scapula, and clavicle. Axilla and Brachial Plexus: Anatomy, pubic area, and legs 
• Perioral (periorificial) dermatitis Dermatitis Any inflammation of the skin. Atopic Dermatitis (Eczema): small erythematous papules around the mouth, nose Nose The nose is the human body’s primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Nose Anatomy (External & Internal), or periorbital Periorbital Orbital and Preseptal Cellulitis areas, most commonly in young women
• Miliaria (“sweat rash Rash Rocky Mountain Spotted Fever”): occurs due to occlusion of eccrine sweat ducts, with extravasation of sweat into dermis Dermis A layer of vascularized connective tissue underneath the epidermis. The surface of the dermis contains innervated papillae. Embedded in or beneath the dermis are sweat glands; hair follicles; and sebaceous glands. Skin: Structure and Functions causing inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation; typically seen in body skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions folds or areas occluded by clothes or other

Predominantly on trunk or extremities

• HIV-associated eosinophilic folliculitis: seen in patients with advanced HIV disease, presenting as intense pruritus and recurrent patches of lesions that lead to scarring and hyperpigmentation; uncertain etiology but possibly related to dysregulated immune response to an infectious agent
• Drug-induced folliculitis: occasionally seen after systemic administration of glucocorticoids, phenytoin, lithium, isoniazid, or cyclosporine
• Keratosis pilaris: presents with asymptomatic, keratotic follicular papules in children and young adults
• Prurigo: refers to intensely pruritic papules or nodules (“prurigo nodularis“), often with no known cause. Chronic scratching or rubbing can cause permanent changes to the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions, including hyperkeratosis Hyperkeratosis Ichthyosis Vulgaris and hyperpigmentation Hyperpigmentation Excessive pigmentation of the skin, usually as a result of increased epidermal or dermal melanin pigmentation, hypermelanosis. Hyperpigmentation can be localized or generalized. The condition may arise from exposure to light, chemicals or other substances, or from a primary metabolic imbalance. Malassezia Fungi, and scarring Scarring Inflammation. Associated skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions disorders and health conditions include atopic eczema Eczema Atopic dermatitis, also known as eczema, is a chronic, relapsing, pruritic, inflammatory skin disease that occurs more frequently in children, although adults can also be affected. The condition is often associated with elevated serum levels of IgE and a personal or family history of atopy. Skin dryness, erythema, oozing, crusting, and lichenification are present. Atopic Dermatitis (Eczema), bullous pemphigoid Bullous pemphigoid Bullous pemphigoid and pemphigus vulgaris are two different blistering autoimmune diseases. In bullous pemphigoid, autoantibodies attack the hemidesmosomes, which connect epidermal keratinocytes to the basement membrane. This attack results in large, tense subepidermal blisters. Bullous Pemphigoid and Pemphigus Vulgaris, allergic reaction to insect bites, iron Iron A metallic element with atomic symbol fe, atomic number 26, and atomic weight 55. 85. It is an essential constituent of hemoglobins; cytochromes; and iron-binding proteins. It plays a role in cellular redox reactions and in the transport of oxygen. Trace Elements deficiency, thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy disease, HIV HIV Anti-HIV Drugs infection, pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care, chronic renal failure Renal failure Conditions in which the kidneys perform below the normal level in the ability to remove wastes, concentrate urine, and maintain electrolyte balance; blood pressure; and calcium metabolism. Renal insufficiency can be classified by the degree of kidney damage (as measured by the level of proteinuria) and reduction in glomerular filtration rate. Crush Syndrome, diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus, and lymphoma Lymphoma A general term for various neoplastic diseases of the lymphoid tissue. Imaging of the Mediastinum.
• Occupational folliculitis: occurs after chronic exposure to oils (“oil folliculitis”), coal tar Coal Tar A by-product of the destructive distillation of coal used as a topical antieczematic. It is an antipruritic and keratoplastic agent used also in the treatment of psoriasis and other skin conditions. Occupational exposure to soots, tars, and certain mineral oils is known to be carcinogenic according to the fourth annual report on carcinogens. Psoriasis, irritants, toxins, or chemicals (e.g., polychlorinated biphenyls [PCBs], dioxins, herbicides). Coal tar Coal Tar A by-product of the destructive distillation of coal used as a topical antieczematic. It is an antipruritic and keratoplastic agent used also in the treatment of psoriasis and other skin conditions. Occupational exposure to soots, tars, and certain mineral oils is known to be carcinogenic according to the fourth annual report on carcinogens. Psoriasis is also used therapeutically for eczema Eczema Atopic dermatitis, also known as eczema, is a chronic, relapsing, pruritic, inflammatory skin disease that occurs more frequently in children, although adults can also be affected. The condition is often associated with elevated serum levels of IgE and a personal or family history of atopy. Skin dryness, erythema, oozing, crusting, and lichenification are present. Atopic Dermatitis (Eczema) and psoriasis Psoriasis Psoriasis is a common T-cell-mediated inflammatory skin condition. The etiology is unknown, but is thought to be due to genetic inheritance and environmental triggers. There are 4 major subtypes, with the most common form being chronic plaque psoriasis. Psoriasis.