Skin Infections and Lesions

Bacterial Skin Infections

• Chronic cases of bacterial skin infections should be referred to a physician for evaluation of possible underlying diseases.
• Lesions associated with bacterial skin infections can last for days, accompanied by throbbing pain and exquisite tenderness.

Erythrasma

• Erythrasma is a chronic bacterial infection caused by Corynebacterium minutissimum.
• It affects intertriginous areas of the toes, groin, and axillae.
• Adults are generally affected, with a higher incidence in obese middle-aged blacks.
• Predisposing factors include diabetes and a warm, humid climate.
• Skin lesions are sharply marginated, brownish red, scaly eruptions that may last for months to years.

Treatment of Bacterial Skin Infections

• Primary impetigo is treated with systemic or topical prescription antibiotics.
• Topical nonprescription antibiotic preparations with neomycin, bacitracin, and polymyxin B sulfate are effective for superficial lesions.
• Cleaning the area with mild soap and water and gently removing loose crusts improves response to topical therapy.

Impetigo

• Impetigo is a bacterial skin infection that can occur in other tissues, such as renal and heart valves.
• Lesions first appear as small red spots that may evolve into characteristic vesicles filled with amber fluid.
• Exudate accumulates and forms yellow or brown crusts (scabs) on the skin surface, often surrounded by erythematous skin.

Ecthyma (Ulcerative Impetigo)

• Ecthyma is an ulcerative bacterial infection caused by Group A streptococci or staphylococci.
• It is a lesion of neglect, which develops in excoriations, insect bites, and minor trauma.
• Children, adolescents, and elderly patients are commonly affected.
• Lesions extend deeper into the dermis than those in impetigo and have a scattered, discrete arrangement.

Erysipeloid

• Erysipeloid is an acute but slowly evolving cellulitis occurring at sites of inoculation, most commonly the hands.
• It is often occupational, associated with handling fish, shellfish, meat, poultry, hides, and bones.
• Infection follows an abrasion, scratch, or puncture wound that occurs while handling organic material containing Erysipelothrix rhusiopathiae.
• The incubation period is 1 to 4 days.
• The highest incidence occurs in adult men during summer and early fall.

Folliculitis

• Folliculitis is a superficial, often bacterial inflammation of hair follicles that heals without scarring.
• Skin areas regularly exposed to tar, grease, mineral oil, adhesive plaster, and plastic occlusive dressings are most susceptible to folliculitis.
• S. aureus folliculitis is aggravated by shaving (e.g., beard area, axillae, legs).

Furuncles and Carbuncles

• A furuncle is an acute, deep-seated, tender, erythematous, inflammatory nodule that evolves from a staphylococcal folliculitis.
• A carbuncle is a conglomerate of multiple coalescing furuncles.
• Children, adolescents, and young adults are frequently affected, and an increased incidence is seen in boys.

Bacterial Skin Infections

• Bacterial skin infections can occur secondary to a contaminated wound or as a primary pyodermic infection.
• Pyodermic infections are characterized by crusted, oozing lesions with variable amounts of purulence and tenderness.

Causes of Infections

• An increase in moisture content can allow microbial growth, leading to infection.
• Breaks in the skin surface, excessive scrubbing and irritation, exposure to water, prolonged occlusion, elevated skin temperature, and local injury can increase the risk of infection.

Types of Bacterial Skin Infections

• Impetigo (superficial infection)
• Ecthyma (ulcerative impetigo)
• Erysipeloid
• Folliculitis (inflammation of hair follicles)
• Furuncles and carbuncles (deep-seated, tender, inflammatory nodules)

Impetigo

• Caused by S. aureus, Group A P-hemolytic streptococci, or a mixed infection.
• Most common in preschool children and young adults.
• Direct contact with infected exudate can result in transmission.
• Chronic cases may indicate underlying disease.

Erythrasma

• Chronic bacterial infection caused by Corynebacterium minutissimum.
• Affects intertriginous areas of the toes, groin, and axillae.
• Common in obese middle-aged adults, especially in warm and humid climates.
• Skin lesions are sharply marginated, brownish red, scaly eruptions that may last for months to years.

Treatment of Bacterial Skin Infections

• Topical antibiotic preparations with neomycin, bacitracin, and polymyxin B sulfate are effective for primary impetigo.
• Systemic antibiotics are usually indicated for ecthyma, folliculitis, and erysipeloid.
• Furuncles and carbuncles may require incision, drainage, and systemic antibiotics.

Erysipeloid

• Caused by Erysipelothrix rhusiopathiae, a gram-positive rod.
• Incubation period is 1 to 4 days.
• Highest incidence occurs in adult men during summer and early fall.
• Characteristic violaceous, sharply marginated lesions composed of macules and plaques.
• Skin symptoms include itching, burning, throbbing, and pain.

Folliculitis

• Superficial, often bacterial inflammation of hair follicles.
• Heals without scarring.
• Skin areas regularly exposed to tar, grease, mineral oil, adhesive plaster, and plastic occlusive dressings are susceptible.
• S. aureus folliculitis is aggravated by shaving.
• Skin lesions commonly last for days.

Furuncles and Carbuncles

• A furuncle is an acute, deep-seated, tender, erythematous, inflammatory nodule that evolves from a staphylococcal folliculitis.
• A carbuncle is a conglomerate of multiple coalescing furuncles.
• Children, adolescents, and young adults are frequently affected, with an increased incidence in boys.

Predisposing Factors for Bacterial Skin Infections

• Crowded living conditions, poor hygiene, and neglected minor trauma can lead to bacterial skin infections
• Impetigo commonly affects face, arms, legs, and buttocks

Impetigo

• Initial appearance: small red spots that evolve into characteristic vesicles filled with amber fluid
• Exudate accumulates and forms yellow or brown crusts (scabs) on the skin surface, often surrounded by erythematous skin

Ecthyma (Ulcerative Impetigo)

• Ulcerative bacterial infection caused by Group A streptococci or staphylococci, or both
• Commonly affects children, adolescents, and elderly patients
• Lesions develop in excoriations, insect bites, or minor trauma, and are commonly distributed on ankles, dorsa of feet, thighs, and buttocks
• Lesions are pruritic and tender, last for weeks, and often heal with a scar

Erysipeloid

• Acute but slowly evolving cellulitis occurring at sites of inoculation, most commonly the hands
• Often occupational, associated with handling fish, shellfish, meat, poultry, hides, and bones
• Lesions commonly last for days, with associated skin symptoms of throbbing pain and exquisite tenderness

Erythrasma

• Chronic bacterial infection caused by Corynebacterium minutissimum
• Affects intertriginous areas of the toes, groin, and axillae
• Commonly affects adults, with a higher incidence in obese middle-aged blacks
• Predisposing factors include diabetes and a warm, humid climate
• Skin lesions are sharply marginated, brownish red, scaly eruptions that may last for months to years

Treatment of Bacterial Skin Infections

• Primary impetigo: systemic or topical prescription antibiotic is indicated
• Topical nonprescription antibiotic preparations with neomycin, bacitracin, and polymyxin B sulfate are effective for superficial and non-extensive lesions
• Cleaning the area with mild soap and water and gently removing loose crusts improves response to topical therapy
• Systemic antibiotics may be necessary to treat concurrent infections in other tissues (e.g., renal, heart valve)

Treatment of Bacterial Skin Infections (cont)

• Ecthyma, folliculitis, and erysipeloid: systemic antibiotic is usually indicated
• Topical nonprescription antibiotics have a limited role in these infections
• Furuncles and carbuncles may be resolved with incision, drainage, and systemic antibiotics

Introduction to Bacterial Skin Infections

• Bacterial skin infections may occur secondary to a contaminated wound or as a primary pyodermic infection
• Pyoderma is a broad term that refers to cutaneous bacterial infection characterized by crusted, oozing lesions with variable amounts of purulence and tenderness
• Cultures of primary cutaneous lesions most often reveal S.aureus and Group A streptococci

Factors Contributing to Bacterial Skin Infections

• Increased moisture content in the skin allows microbial growth, leading to infection
• Break in the intact skin surface allows large numbers of pathogenic organisms to be introduced into the inner layers
• Excessive scrubbing, irritation, exposure to water, prolonged occlusion, elevated skin temperature, or local injury increase the risk of infection

Types of Bacterial Skin Infections

• Impetigo
• Ecthyma (ulcerative impetigo)
• Erysipeloid
• Folliculitis
• Furuncles and carbuncles
• Erythrasma

Bacterial Skin Infections

• Bacterial skin infections can occur secondary to a contaminated wound or as a primary pyodermic infection.
• Pyoderma is a broad term that refers to cutaneous bacterial infection characterized by crusted, oozing lesions with variable amounts of purulence and tenderness.

Causes of Infections

• Normally, the stratum corneum has only about 10% water content, which is enough to ensure elasticity but is generally below that needed to support luxuriant microbial growth.
• An increase in moisture content can allow microbial growth, leading to infection.
• A break in the intact skin surface can allow large numbers of pathogenic organisms to be introduced into the inner layers.
• Risk factors for infection include:
  • Excessive scrubbing and irritation of the skin
  • Excessive exposure to water
  • Prolonged occlusion
  • Excessively elevated skin temperature
  • Local injury

Types of Bacterial Skin Infections

• Impetigo: a very superficial infection of the skin caused by S.aureus, Group A P-hemolytic streptococci, or a mixed infection.
• Ecthyma (ulcerative impetigo): an ulcerative bacterial infection caused most frequently by Group A streptococci or staphylococci or both.
• Erysipeloid: an acute but slowly evolving cellulitis occurring at sites of inoculation, most commonly the hands.
• Folliculitis: an infection of the hair follicle.
• Furuncles and carbuncles: infections of the hair follicle that can lead to abscess formation.
• Erythrasma: a chronic bacterial infection that affects the intertriginous areas of the toes, groin, and axillae.

Impetigo

• Impetigo is most common in preschool children and young adults.
• Predisposing factors include:
  • Crowded living conditions
  • Poor hygiene
  • Neglected minor trauma
• Lesions first appear as small red spots that may evolve into characteristic vesicles filled with amber fluid.
• Exudate accumulates and forms yellow or brown crusts (scabs) on the skin surface, often surrounded by erythematous skin.
• Face, arms, legs, and buttocks are common affected areas.

Ecthyma (ulcerative impetigo)

• Ecthyma is a lesion of neglect, which develops in excoriations, insect bites, minor trauma in elderly patients, soldiers, sewage workers, alcoholics, and homeless people.
• These lesions extend much deeper into the dermis than those in impetigo.
• They have a scattered, discrete arrangement and are commonly distributed on ankles, dorsa of feet, thighs, and buttocks.
• Lesions are pruritic and tender; they last for weeks and often heal with a scar.

Erysipeloid

• Erysipeloid is often occupational, associated with handling fish, shellfish, meat, poultry, hides, and bones.
• Chronic cases should be referred to a physician for evaluation of a possible underlying disease.
• These lesions commonly last for days, with associated skin symptoms of throbbing pain and exquisite tenderness.
• Some patients are subject to recurrent furunculosis.

Erythrasma

• Erythrasma is a chronic bacterial infection that affects the intertriginous areas of the toes, groin, and axillae.
• Adults are generally affected, with a higher incidence in obese middle-aged blacks.
• Predisposing factors include diabetes and a warm, humid climate.
• The skin lesions are sharply marginated, brownish red, scaly eruptions that may last for months to years.
• Irritation may be the only skin symptom.

Treatment of Bacterial Skin Infections

• For the treatment of primary impetigo, a systemic or topical prescription antibiotic is indicated.
• Topical nonprescription antibiotic preparations with neomycin, bacitracin, and polymyxin B sulfate seem to be most effective when lesions are superficial and are not extensive.
• Cleaning the area with mild soap and water and gently removing loose crusts should improve response to topical therapy.
• For the treatment of ecthyma, folliculitis, and erysipeloid, a systemic antibiotic is usually indicated.
• The role of topical nonprescription antibiotics in these infections is very limited.
• Furuncles and carbuncles may be resolved with incision, drainage, and the prescription of systemic antibiotics by a physician.

Bacterial Skin Infections

• Bacterial skin infections can occur secondary to a contaminated wound or as a primary pyodermic infection.
• Pyodermic infections are characterized by crusted, oozing lesions with variable amounts of purulence and tenderness.

Causes of Infections

• An increase in moisture content can allow microbial growth, leading to infection.
• Breaks in the skin surface, excessive scrubbing and irritation, exposure to water, prolonged occlusion, elevated skin temperature, and local injury can increase the risk of infection.

Types of Bacterial Skin Infections

• Impetigo (superficial infection)
• Ecthyma (ulcerative impetigo)
• Erysipeloid
• Folliculitis (inflammation of hair follicles)
• Furuncles and carbuncles (deep-seated, tender, inflammatory nodules)

Impetigo

• Caused by S. aureus, Group A P-hemolytic streptococci, or a mixed infection.
• Most common in preschool children and young adults.
• Direct contact with infected exudate can result in transmission.
• Chronic cases may indicate underlying disease.

Erythrasma

• Chronic bacterial infection caused by Corynebacterium minutissimum.
• Affects intertriginous areas of the toes, groin, and axillae.
• Common in obese middle-aged adults, especially in warm and humid climates.
• Skin lesions are sharply marginated, brownish red, scaly eruptions that may last for months to years.

Treatment of Bacterial Skin Infections

• Topical antibiotic preparations with neomycin, bacitracin, and polymyxin B sulfate are effective for primary impetigo.
• Systemic antibiotics are usually indicated for ecthyma, folliculitis, and erysipeloid.
• Furuncles and carbuncles may require incision, drainage, and systemic antibiotics.

Erysipeloid

• Caused by Erysipelothrix rhusiopathiae, a gram-positive rod.
• Incubation period is 1 to 4 days.
• Highest incidence occurs in adult men during summer and early fall.
• Characteristic violaceous, sharply marginated lesions composed of macules and plaques.
• Skin symptoms include itching, burning, throbbing, and pain.

Folliculitis

• Superficial, often bacterial inflammation of hair follicles.
• Heals without scarring.
• Skin areas regularly exposed to tar, grease, mineral oil, adhesive plaster, and plastic occlusive dressings are susceptible.
• S. aureus folliculitis is aggravated by shaving.
• Skin lesions commonly last for days.

Furuncles and Carbuncles

• A furuncle is an acute, deep-seated, tender, erythematous, inflammatory nodule that evolves from a staphylococcal folliculitis.
• A carbuncle is a conglomerate of multiple coalescing furuncles.
• Children, adolescents, and young adults are frequently affected, with an increased incidence in boys.