Infections of the Skin: Furunculosis and Carbuncle

Furunculosis (Boils)

• A deep-seated follicular and perifollicular infection caused by Staphylococcus aureus, resulting in necrosis.
• Common in adolescent boys.
• Typically presents as 1-2 tender, firm, red, follicular nodules that become necrotic and discharge their central core.
• Lesions heal with minimal scarring.
• Occasionally, lymphadenopathy and fever may occur.
• Sites include hair-bearing areas such as the face, axillae, buttocks, and perineal region.

Carbuncle

• Caused by Staphylococcus aureus.
• A deep infection of contiguous hair follicles, frequently occurring in diabetics and patients on steroid therapy.
• Common in adult males.
• Characterized by constitutional symptoms like fever.
• Presents as a tender, indurated, lobulated, intensely erythematous plaque discharging pus from multiple openings.
• The back is the most common site of involvement.

Erysipelas

• Caused by Streptococcus pyogenes entering through a superficial break in the skin.
• A superficial infection that recurs if pre-existing lymphedema or venous stasis is present.
• Acute erythematous, warm, indurated, rapidly spreading plaques with a sharply defined margin. Superficial vesiculation may occur.
• Constitutional symptoms precede skin lesions.
• Lower limbs are the most common site, but the upper limbs and face can also be affected.
• Lymphangitis and lymphedema predispose to recurrent lesions.
• Facial erysipelas, if left untreated, can be fatal.
• Complications include staphylococcal scalded skin syndrome.

Staphylococcal Scalded Skin Syndrome

• Associated with Staphylococcus aureus infection at various sites such as the ear, lungs, and skin.
• Occurs primarily in infants.
• Onset is acute, characterized by fever, skin tenderness, and peeling of skin in thin sheets.
• Clinically, the skin appears scalded.
• Mucous membranes are spared.

Ecthyma

• A deeper infection caused by Streptococcus pyogenes, Staphylococcus aureus, or both.
• Predisposing factors include poor hygiene, malnutrition, and minor injuries.
• Starts as a small bulla or pustule on an erythematous base, forming a crusted, indurated, tender plaque with an erythematous, edematous areola.
• Removal of adherent crust reveals an irregular ulcer.
• Lesions heal without scarring.
• Common sites include the buttocks, thighs, and legs.

Superficial Folliculitis

• Three types: infectious, chemical, and mechanical.
• Infectious type is caused by Staphylococcus aureus.
• Chemical type is due to occupational or cosmetic exposure.
• Mechanical type includes pseudofolliculitis (after shaving) in the beard region and post-waxing folliculitis.
• Presents as dome-shaped follicular pustules.
• Sites include the legs, beard region (pseudofolliculitis), thighs, and deltoid region (post-waxing folliculitis).

Deep Folliculitis

• Caused by Staphylococcus aureus.
• Deep-seated, erythematous perifollicular papules and pustules.
• Recurrences are common in the same area.

Cellulitis

• Caused by Streptococcus pyogenes entering through a superficial break in the skin.
• A deeper infection that recurs if pre-existing lymphedema or venous stasis is present.
• Erythematous, warm, indurated, rapidly spreading plaques with an ill-defined lesion and deeper involvement.
• Constitutional symptoms precede skin lesions.
• Lower limbs are the most common site, but the upper limbs and face can also be affected.
• Lymphangitis and lymphedema predispose to recurrent lesions.
• Recurrences may result in lymphedema.

Furunculosis (Boils)

• Deep seated follicular and perifollicular infection caused by Staphylococcus aureus, leading to necrosis.
• Usually presents as 1-2 tender, firm, red, follicular nodules that become necrotic and discharge their central core.
• Most often affects adolescent boys.
• Lesions typically heal with minimal scarring.
• May be accompanied by lymphadenopathy and fever.
• Sites include hair-bearing areas: face, axillae, buttocks, and perineal region.

Carbuncle

• Deep infection of contiguous hair follicles caused by Staphylococcus aureus.
• More common in diabetics and patients on steroid therapy.
• Primarily affects adult males.
• Characterized by tender, indurated, lobulated, intensely erythematous plaques with multiple pus-draining openings.
• Back is the most common site of involvement.
• Patients experience constitutional symptoms, such as fever.

Erysipelas

• Superficial skin infection caused by Streptococcus pyogenes.
• Bacteria enter through a superficial skin break.
• Recurrences are common, especially in individuals with pre-existing lymphedema or venous stasis.
• Presents as acute, erythematous, warm, indurated plaques that spread rapidly.
• Plaques have sharply defined margins and may exhibit superficial vesiculation.
• Constitutional symptoms are typical and precede skin lesions.
• Primarily affects lower limbs, but can also involve upper limbs and face.
• Lymphangitis and lymphedema can predispose to recurrent lesions.
• Complications include facial erysipelas (potentially fatal if left untreated), and involvement of mucous membranes.

Staphylococcal Scalded Skin Syndrome

• Staphylococcus aureus infection at various sites, including ears (otitis media), lungs (pneumonitis), and skin (minor wounds).
• Primarily affects infants.
• Characterized by rapid onset of fever, skin tenderness, and peeling of skin in thin sheets.
• Skin appears scalded, while mucous membranes are spared.

Ecthyma

• Deeper infection caused by Streptococcus pyogenes, Staphylococcus aureus, or both.
• Predisposing factors include poor hygiene, malnutrition, and minor injuries.
• Presents as small bullae or pustules on an erythematous base, which quickly form a crusted, indurated, tender plaque with an erythematous, edematous areola.
• Removal of the crust reveals an irregular ulcer.
• Lesions usually heal without scarring.
• Common sites are buttocks, thighs, and legs.

Superficial Folliculitis

• Three main types:
  • Infectious (Staphylococcus aureus)
  • Chemical (occupational/cosmetic exposure)
  • Mechanical (pseudofolliculitis after shaving, post-waxing folliculitis).
• Presents as dome-shaped follicular pustules.

Deep Folliculitis

• Caused by Staphylococcus aureus.
• Characterized by deep-seated, erythematous perifollicular papules and pustules.
• Recurrences are possible in the same area.

Cellulitis

• Deeper skin infection caused by Streptococcus pyogenes.
• Bacteria enter through a superficial skin break.
• Recurrent cellulitis is common in individuals with pre-existing lymphedema or venous stasis.
• Presents as erythematous, warm, indurated, rapidly spreading plaques with ill-defined borders.
• Constitutional symptoms typically precede skin lesions.
• Primarily affects lower limbs, but can also involve upper limbs and face.
• Lymphangitis and lymphedema predispose to recurrent lesions.
• Complications include recurrent lesions leading to lymphedema.

Furunculosis (Boils)

• Deep seated follicular and perifollicular infection caused by Staphylococcus aureus, culminating in necrosis.
• Commonly affects adolescent boys.
• Presents as 1-2 tender, firm, red, follicular nodules that become necrotic and discharge their central core.
• Lesions heal with barely perceptible scarring.
• Occasionally associated with lymphadenopathy and fever.
• Frequently occurs on hair-bearing sites like the face, axillae, buttocks, perineal region, and scalp.
• Treated with hot fomentation and appropriate antibiotics.
• Chronic and recurrent cases require treatment of the carrier state with topical mupirocin.

Carbuncle

• Deep infection of contiguous hair follicles induced by Staphylococcus aureus.
• More prevalent in individuals with diabetes or those on steroid therapy.
• Commonly affects adult males.
• Characterized by constitutional symptoms like fever, tender, indurated, lobulated, intensely erythematous plaques discharging pus from multiple openings.
• Back is the most common site of involvement.
• Requires drainage of deep-seated pus pockets and aggressive treatment with penicillinase-resistant antibiotics like flucloxacillin.

Erysipelas

• Superficial skin infection caused by Streptococcus pyogenes, entering through a superficial skin break.
• Recurrences are common in cases of pre-existing lymphedema or venous stasis.
• Exhibits acute erythematous, warm, indurated, rapidly spreading plaques with a sharply defined margin.
• Superficial vesiculation may occur on the plaques.
• Constitutional symptoms precede the onset of skin lesions.
• Primarily affects the lower limbs, but can also occur in the upper limbs and face.
• Lymphangitis and lymphedema predispose to recurrent lesions.
• Untreated facial erysipelas can be fatal.
• Mucous membranes can be involved.
• Can lead to staphylococcal scalded skin syndrome.
• Diagnosed through Gram stain showing polymorphs with intracellular and extracellular gram-positive cocci in clusters, and culture confirming Staphylococcus aureus.
• Treated with local hygiene measures and antibiotics.
• Extensive lesions require systemic antistaphylococcal antibiotics like flucloxacillin.

Staphylococcal Scalded Skin Syndrome

• Staphylococcus aureus infection at various sites, including the ear (otitis media), lungs (pneumonitis), and skin (trivial wounds).
• Primarily affects infants.
• Presents as an acute onset with fever, skin tenderness, and peeling of skin in thin sheets.
• Clinically appears as scalded skin.
• Mucous membranes are spared.
• Diagnosed through Gram stain and pus culture.
• Managed with supportive and nursing measures along with aggressive treatment using intravenous antistaphylococcal antibiotics followed by oral therapy.

Ecthyma

• Deeper infection caused by either Streptococcus pyogenes, Staphylococcus aureus, or both.
• Precipitated by factors like poor hygiene, malnutrition, and minor injuries.
• Characterized by small bullae/pustules on an erythematous base, quickly forming a crusted, indurated, tender plaque with an erythematous, edematous areola.
• Removal of the adherent crust reveals an irregular ulcer.
• Lesions heal without scarring.
• Common sites include the buttocks, thighs, and legs.
• Treated with local hygiene and systemic antibiotics like penicillin.

Superficial Folliculitis

• Classified into three types:
  • Infectious: Caused by Staphylococcus aureus.
  • Chemical: Induced by occupational or cosmetic exposure.
  • Mechanical: Pseudofolliculitis (after shaving) in the beard region and post-waxing folliculitis.
• Presents as dome-shaped follicular pustules.
• Occurs on the legs (superficial folliculitis), beard region (pseudofolliculitis), and thighs and deltoid region (post-waxing folliculitis).
• Treated with topical antibiotics for infectious folliculitis and topical steroid antibiotics for chemical and mechanical folliculitis.

Deep Folliculitis

• Caused by Staphylococcus aureus.
• Presents as deep-seated, erythematous perifollicular papules and pustules.
• Recurrences are possible in the same area.
• Treated symptomatically with rest, limb elevation, and non-steroidal anti-inflammatory drugs for pain relief.
• Acute episodes require parenteral penicillin, while penicillin-sensitive patients require alternative antibiotics.

Cellulitis

• Deeper infection caused by Streptococcus pyogenes, entering through a superficial skin break.
• Recurrent cellulitis is common in cases of pre-existing lymphedema or venous stasis.
• Exhibits erythematous, warm, indurated, rapidly spreading plaques with an ill-defined margin.
• Constitutional symptoms precede the onset of skin lesions.
• Predominantly affects the lower limbs, but can also occur in the upper limbs and face.
• Lymphangitis and lymphedema increase the risk of recurrent lesions.
• Recurrences may lead to lymphedema.
• Treated symptomatically with rest, limb elevation, and non-steroidal anti-inflammatory drugs for pain relief.
• Acute episodes require parenteral penicillin, while penicillin-sensitive patients need alternative antibiotics.

Diagnosis of Bacterial Skin Infections

• Visual examination of lesions for features such as size, color, and distribution is part of the clinical assessment.
• Patient history is crucial, including information on symptom onset, duration, and any potential exposure.
• Laboratory tests, such as culture and sensitivity tests from wound swabs or drainage, assist in identifying the causative bacteria.
• Blood tests may be required if systemic infection is suspected.
• Imaging studies, such as ultrasound or CT scans, are helpful for complicated infections that involve deeper tissues.

Treatment Options for Bacterial Infections

• Topical antibiotics, like mupirocin and fusidic acid, are effective for localized infections.
• Oral antibiotics are generally prescribed for moderate to severe infections, with common options including:
  • Penicillins (e.g., Dicloxacillin)
  • Cephalosporins (e.g., Cephalexin)
  • Clindamycin for infections caused by methicillin-resistant Staphylococcus aureus (MRSA)
• Drainage of abscesses is important for clearing the infection.
• Adjunctive therapies include antiseptics, wound care, and measures to support immune function.

Common Bacterial Pathogens in Dermatology

• Staphylococcus aureus is a prevalent cause of skin infections like impetigo, folliculitis, and furuncles.
• Streptococcus pyogenes is commonly associated with cellulitis and impetigo.
• Pseudomonas aeruginosa often causes infections in burn wounds and moist environments.
• Propionibacterium acnes plays a role in the development of acne vulgaris.

Clinical Manifestations of Bacterial Infections

• Impetigo presents with characteristic honey-colored crusts, often around the mouth and nose.
• Folliculitis involves inflammation of hair follicles, leading to red bumps or pustules.
• Furuncles are painful, inflamed nodules that form around infected hair follicles.
• Carbuncles are larger collections of interconnected furuncles, potentially accompanied by systemic signs like fever and malaise.
• Cellulitis is a widespread infection affecting the dermis and subcutaneous tissue, characterized by redness, swelling, warmth, and pain.

Infection Control Measures

• Good hygiene practices, such as regular handwashing and personal hygiene, are vital to prevent bacterial skin infections.
• Proper wound care, including cleaning and dressing cuts and abrasions, is crucial for minimizing infection risk.
• Isolation measures may be necessary for infections like impetigo until effective treatment is initiated.
• Patient education about transmission and prevention strategies is essential for minimizing the spread of bacterial skin infections.

Deep Folliculitis

• Deep infection of hair follicles, often leading to painful nodules.
• Staphylococcus aureus is the primary causative organism.
• Symptoms include tenderness, redness, and potential pus drainage.
• Management typically involves drainage of abscesses and oral antibiotics, especially if the infection is widespread or recurrent.

Furunculosis

• Recurrent furuncles, often appearing in clusters.
• Predisposing factors include poor hygiene, obesity, diabetes, and immunocompromised states.
• Treatment is similar to individual furuncles, but antibiotic prophylaxis may be necessary in some cases.

Carbuncle

• Collection of interconnected furuncles, forming a larger abscess.
• Multiple openings on the skin are characteristic, along with pus drainage and possible systemic symptoms like fever.
• Management involves incision and drainage, and systemic antibiotics are often indicated for extensive cases.

Cellulitis

• Cellulitis is a bacterial infection of the skin.
• The most common cause is Streptococcus pyogenes.
• Cellulitis can occur after a superficial break in the skin.
• Deep infection with rapidly spreading plaques.
• The infection is often accompanied by lymphedema and venous stasis
• Symptoms include erythema, warmth, induration, and pain.
• Cellulitis is more common in the lower limbs, but can also affect the upper limbs and face.
• Treatment involves rest, limb elevation, nonsteroidal anti-inflammatory drugs, and antibiotics.

Impetigo Contagiosa

• Impetigo contagiosa is highly contagious.
• Primarily affects school children
• Caused by Staphylococcus aureus or Streptococcus pyogenes.
• The infection can occur in outbreaks.
• The infection is characterized by thin-walled blisters on an erythematous base that rupture to form an area of exudation and honey-colored crusts.
• The lesions spread peripherally, without central healing.
• Removal of the crusts reveals an erosion.
• Typically involve the face, especially around the mouth and nose
• Treatment involves local hygiene and topical antibiotics like fusidic acid and mupirocin.

Bullous Impetigo

• Bullous impetigo is caused by certain strains of Staphylococcus aureus.
• Typically affects infants.
• The infection is characterized by bullae with turbid fluid collection, without an erythematous halo.
• Bullae rupture after a few days to form thin, varnish-like crusts.
• Lesions may heal in the center to form annular plaques.
• Mucous membranes may be involved.
• Requires treatment with antibiotics to prevent staphylococcus scalded skin syndrome.

Staphylococcal Scalded Skin Syndrome

• Staphylococcal scalded skin syndrome is a serious bacterial infection.

• Caused by Staphylococcus aureus that colonizes the skin and other body sites.

• The infection is characterized by acute onset of fever and skin tenderness, followed by extensive peeling of the skin in thin sheets.

• Skin appears clinically scalded.

• Mucous membranes are spared.

• Treatment involves aggressive IV antistaphylococcal antibiotics followed by oral therapy.

Ecthyma

• Ecthyma is deeper infection caused by Streptococcus pyogenes, Staphylococcus aureus, or both
• Caused by streptococcus pyogenes/Staphylococcus aureus, or both
• Primarily affects poorly hygienic individuals.
• Predisposing factors include poor hygiene, malnutrition, and minor injuries.
• The infection presents as a small bulla/pustule on an erythematous base, forming a crusted, indurated, and tender plaque.
• Removal of the crust reveals an irregular ulcer.
• Lesions heal without scarring.
• Typically affects the buttocks, thighs, and legs.
• Treatment involves local hygiene, systemic antibiotics like penicillin.

Superficial Folliculitis

• Superficial folliculitis is a common skin condition.
• Caused by Staphylococcus aureus (infectious), occupational/cosmetic exposure (chemical), or pseudofolliculitis (after shaving) (mechanical).
• The condition is characterized by dome-shaped follicular pustules.
• Typically affects the legs, beard region, and thighs and deltoid region (post waxing folliculitis).
• Treatment involves topical antibiotics for infectious folliculitis and topical steroid antibiotics for chemical and mechanical folliculitis.

Deep Folliculitis

• Deep folliculitis is a more serious infection.
• Typically affects the beard and scalp.
• Caused by Staphylococcus aureus.
• The condition presents as deep-seated, erythematous perifollicular papules and pustules.
• Requires treatment with systemic antibiotics.

Furunculosis (Boils)

• Furunculosis (boils) are a common bacterial infection.
• Caused by Staphylococcus aureus.
• The condition presents as 1-2 tender, firm, red, follicular nodules that become necrotic and discharge a central core.
• Lesions heal with barely perceptible scarring.
• Boils usually occur on hair-bearing sites.
• The condition is usually self-limiting, but may require antibiotics.

Carbuncle

• Carbuncles are a severe skin infection.
• Caused by Staphylococcus aureus, and are a deep infection of contiguous hair follicles.
• More common in diabetic and steroid therapy patients.
• The condition presents presents as a tender, indurated, lobulated, intensely erythematous plaque that discharges pus from many openings.
• The back is the most common site of involvement.
• Aggressive treatment with flucloxacillin or other penicillinase-resistant antibiotics is necessary.

Erysipelas

• Erysipelas is a bacterial infection of the skin.
• Caused by Streptococcus pyogenes.
• The infection can occur after a superficial break in the skin.
• The condition presents as acute erythematous, warm, indurated rapidly spreading plaques.
• The margin is sharply defined and superficial vesiculation may occur on the plaque.
• The infection is accompanied by fever, chills, and malaise.
• Usually affects the lower limbs.
• Untreated facial erysipelas can be fatal.

Impetigo Causes

• Bacterial Infection: Primarily caused by Staphylococcus aureus or Streptococcus pyogenes.
• Skin Breakdown: Can occur through cuts, insect bites, or skin conditions (like eczema).
• Contagious: Spreads easily through direct contact with infected sores or contaminated objects.
• Weakened Immune System: Individuals with a weakened immune system are more susceptible.

Impetigo Symptoms

• Skin Lesions: Appear as red sores or blisters that ooze and form a honey-colored crust.
• Location: Commonly found on the face, especially around the nose and mouth, but can occur anywhere.
• Itching and Pain: Lesions may be itchy or painful.
• Swollen Lymph Nodes: Can occur if the infection spreads.

Impetigo Complications

• Spread of Infection: Can lead to cellulitis or other skin infections.
• Kidney Issues: Rarely, poststreptococcal glomerulonephritis can occur.
• Scarring: Severe cases may lead to permanent skin damage.
• Secondary Infections: Pre-existing skin conditions can worsen due to impetigo.

Impetigo Treatment

• Topical Antibiotics: Mupirocin or retapamulin are applied directly to the affected area.
• Oral Antibiotics: May be prescribed for severe cases or when the infection is widespread.
• Hygiene Practices: Regularly wash hands and clean lesions to prevent spreading.
• Preventing Contagion: Individuals with impetigo should stay home until treatment is effective, typically 24-48 hours after starting antibiotics.
• Wound Care: Keeping the area clean and dry promotes healing.