Unit 12B Skin Infection & Burns

DISORDERS OF SKIN INTEGRITY AND FUNCTION

self study: sweat gland → apocrine, skin variation and patient ed for dark skinned patients

Chapter 52

Primary Skin Disorders

  • Definition: Primary skin disorders encompass various conditions affecting the skin directly.

  • Categories of Primary Skin Disorders:
      - Disorders of pigmentation
      - Infectious processes
      - Acne and rosacea
      - Allergic and hypersensitivity dermatoses
      - Papulosquamous dermatoses
      - Arthropod infestations

Pigmentary Skin Disorders

  • Overview: Pigmentary skin disorders involve the melanocytes, which are responsible for the production of melanin.

  • Types of Pigmentary Disorders:
      - Absence of melanin production: Examples include vitiligo and albinism.
      - Increased melanin or other pigments: Examples include congenital dermal melanocytosis (formerly known as Mongolian blue spots) and melasma.

  • Emotional Impact: All types can lead to significant emotional distress, including anxiety and depression.

Vitiligo

  • Definition: A pigmentary disorder characterized by the loss of skin color in patches; affects individuals of all skin colors and ages.

  • Onset Age: Approximately 50% of cases begin before age 20.

  • Gender Comparison: The condition affects females and males equally.

  • Social Concerns: More visible in individuals with darker skin, making it a social issue.

  • Etiology: The exact cause is unknown but theories suggest:
      1. Autoimmune mechanism: Loss of melanocytes leads to depigmented patches.
      2. Genetics: Family history may play a role.
      3. Acquired Factors: Stress or physical trauma can precipitate the condition.

  • Additional Factors:
      - High serum homocysteine levels: May contribute to the destruction of melanocytes.
      - Associated Conditions: Includes hypothyroidism, Graves disease, Addison's disease, pernicious anemia, diabetes mellitus, and melanoma.

Clinical Manifestations:

  • Lesions: Sudden appearance of white patches on skin, smooth borders, located commonly on the face, axillae, neck, or extremities.

  • Sizes of Patches: Range from small macules to large areas; large macules are more common.

  • Coloration of Depigmented Areas: Appears white, pale, or grayish-blue.

  • Mechanisms in Affected Areas:
      1. Melanocytes that no longer produce melanin.
      2. No functioning melanocytes present.
      3. Very few functioning melanocytes.

  • Ultraviolet Sensitivity: Affected areas are prone to sunburn and tend to enlarge over time.

Types of Vitiligo

  • Vitiligo A:
      - Later onset in life; higher frequency.
      - White patches are symmetrical with discrete borders and slowly progressives cover hands, face, and body folds.

  • Vitiligo B:
      - Earlier onset; segmental form.
      - White patches are asymmetrical and can occur anywhere on the body.

Albinism

  • Definition: Congenital genetic disorder characterized by a complete or partial absence of pigment in the skin, hair, and eyes.

  • Prevalence: Affects individuals of all races; over 10 types identified.

  • Appearance: Individuals present with pale skin, white or yellow hair, and light-colored or pink eyes.

  • Common Type: Recessively inherited oculocutaneous albinism results from a normal number of melanocytes but with little to no tyrosinase, the enzyme necessary for melanin production.

  • Ocular Problems: Individuals may experience:
      - Extreme light sensitivity
      - Refractive errors
      - Foveal hypoplasia
      - Nystagmus

Melasma

  • Definition: A dermatological disorder characterized by the appearance of darkened macules on the face.

  • Demographics: More commonly seen in females, especially during pregnancy or while using hormonal contraception.

  • Resolution: Often resolves after childbirth or discontinuing hormonal use and exacerbates with sun exposure.

  • Popular Among: Individuals with darker skin tones, especially those from Asia, India, the Caribbean, and Central and South America.

Infectious Processes

Overview

  • Vulnerability: Skin is susceptible to invasion by various potentially infectious microorganisms such as fungi, bacteria, and viruses.

  • Defense Mechanisms: Skin flora, sebum, immune responses, and other protective mechanisms typically prevent infections.

  • Infection Factors: Likelihood of infection depends on the virulence of the infecting agent and the immune capability of the host.

Superficial Fungal Infections → common

  • Definition: Fungi are free-living, saprophytic organisms; many strains are part of normal skin flora.

  • Classification:
      - Two types of fungi: Yeasts and Molds.
      - Yeasts: Grow as single cells, reproduce asexually (e.g., Candida albicans).
      - Molds: Form long filaments known as hyphae.

  • Infections: Fungal (mycotic skin infections) can be superficial (most common) or deep.
      - Superficial Mycoses: Includes tinea or ringworm, affecting only the keratinized tissue of skin, hair, and nails.
      - Deep Fungal Infections: Involve the epidermis, dermis, and subcutis, especially concerning in immunocompromised patients.

Pathogenesis of Superficial Mycoses

  • Mechanism: Fungi feed on dead keratinized epidermal cells and secrete enzymes that digest keratin, leading to skin, nail, and hair breaking, and other related conditions.

  • Specific Tinea Infections:
      - Tinea Corporis: Ringworm affecting the body
      - Tinea Faciale: Affects the face and neck.
      - Tinea Capitis: Affects the scalp.
      - Tinea Manus: Affects the hands.
      - Tinea Pedalis: Affects the feet.
      - Tinea Unguium: Affects the nails.
      - Tinea Cruris: Affects the genital area.

  • Tinea Corporis (Ringworm of the Body):
      - Common etiological agent is M. canis.
      - More prevalent in children than adults.
      - Transmission: Typically from contact with infected pets or children→ KNOW THIS
      - Clinical Manifestation: Lesions appear as circular or oval patches on exposed skin:     -        -trunk, limbs, back, or buttocks
      - Symptoms: May include pruritus, mild burning sensation, and erythema.

  


  > Note: Describing a dermatophytic skin infection characterized by erythematous, pruritic, annular lesions with raised borders and central clearing.

Bacterial Infections

Overview

  • Normal Flora: Bacteria are a component of normal skin flora; most are non-pathogenic.

  • Pathogenicity: Skin infections can manifest when pathogenic bacteria invade, leading to superficial or systemic conditions.

  • Classification:
      -     Primary Infections: e.g., impetigo and ecthyma (superficial).
      -     Secondary Infections: Involve deeper cutaneous infections, such as infected ulcers.
      -     Diagnosis: Generally based on cultures from the site of infection.

Impetigo

  • Definition: A common, superficial bacterial infection predominantly seen in young children (2-5), caused by Staphylococcus or group A beta-hemolytic streptococci.

  • Age Group: Most prevalent among infants and young children, adults can get it

  • Seasonal Incidence: Higher incidence during warm months or in warm, moist climates.

  • Clinical Manifestations:
      - Lesions can present as small vesicles or pustules, or as large bullae, particularly on the face.
      - Lesions eventually rupture, leading to a denuded area that excretes serous fluid, forming a honey-colored crust.
      - Pruritus often accompanies these lesions, sometimes leading to excoriation and the potential for further infection.


  


  > Note: Characteristic vesicles or bullae rupture to create a honey-colored crust.

  • Complications: Although rare, untreated streptococcal impetigo may lead to poststreptococcal glomerulonephritis.

  • Treatment: Topical or systemic antibiotics depending on infection extent.

Bullous Impetigo

  • Definition: A variant of impetigo primarily due to Staphylococcus aureus.

  • Population Affected: Common in children, but typically not contaminated by streptococci.

  • Presentation: Thin bullae erupt, coalesce, and can appear anywhere on the body, predominantly affecting the face.

Ecthyma

  • Definition: A more severe, ulcerative form of impetigo.

  • Etiology: Often secondary to minor trauma; caused by group A beta-hemolytic streptococci, S. aureus, or Pseudomonas.

  • Areas Affected: Commonly found on buttocks and thighs in children.

  • Clinical Features: Develops similarly to impetigo but can result in ulcerations and scarring.

  • Symptoms: There may be a low-grade fever with extensive ecthyma, indicating systemic spread.

  • Treatment: Often involves systemic antibiotics.

Viral Infections

Overview

  • Definition: Viruses are intracellular pathogens that depend on host cells for reproduction.

  • Structure: They consist of a DNA or RNA core encased in a protein coat.

  • Skin Lesions: Viruses, particularly DNA viruses, invade keratinocytes, reproduce, and can lead to cell proliferation or death.

  • Increased Viral Infections: Notable rise attributed to increased corticosteroid use, alterations in skin flora from antibiotics, leading to a reduction in bacterial infections but an increase in viral infections.

Verrucae (Warts)

  • Definition: Common benign papillomas caused by human papillomavirus (HPV).

  • Transmission: Spread via direct contact or autoinoculation.

  • Classification by Morphology and Location:
      - Variations based on anatomical location and HPV type, with over 80 HPV types
      - Common Warts (verrucae vulgaris): Typically seen on hands dorsal side (top)

  • Verruca plana (flat warts): common on the face/hands dorsal (Top)

  • Verruca plantaris/palmaris: found on palms/soles of feet.

  • Immune Response: Warts often resolve spontaneously as immunity against the virus develops, which can take several months to years.

Herpes Simplex

  • Definition: Caused by the herpes simplex virus (HSV), leading to skin and mucous membrane infections (cold sores, fever blisters).

  • Types of HSV:
      - HSV-1: Primarily spreads via respiratory droplets; associated     with oropharyngeal infections, contracted in childhood

    • primary and recurrent

    •   - HSV-2: Associated with genital infections.

    •   - Increase in Transmission Risk: HSV-1 genital infections and HSV-2 oral infections are becoming increasingly common.

  • HSV1 Primary Clinical Features:
      - Fever, sore throat, painful vesicles, and ulcers in oral mucosa.
      - Most severe primary infections are common in early childhood (1-5 years).
      - After the initial infection, HSV remains latent in the trigeminal and other dorsal root ganglia, with recurrent symptoms generally less severe and localized.
      - Reactivation Triggers: Stress, menses, hormonal changes, injury, and UV exposure.

  • üRecurrent or secondary HSV-1 lesions usually begin with a burning or tingling sensation, the prodrome

  • üUmbilicated vesicles and erythema follow, progressing to pustules, ulcers, and crusts before healing (see Fig. 52.9)

    §HSV-1 lesions are most common on the lips, face, mouth, nasal septum, and nose

    oWhen a lesion is active, HSV-1 is shed, with the associated risk of virus transmission to others
      - Healing Duration: Typically takes 10-14 days with pain and lesions healing gradually.

Herpes Zoster (Shingles)

  • Definition: Characterized by acute, localized vesicular rash over a dermatomal segment of skin, affecting approximately 10-20% of the population.

  • Etiology: Caused by reactivation of the varicella-zoster virus from previous chickenpox infection, lying dormant in sensory dorsal root ganglia

    • Reactivated virus travels from the ganglia to the skin on the corresponding dermatome

  • Demographics: More common in > 60 older adults but can occur at any age.

  • Clinical Manifestations:
      - Lesions typically preceded by a prodrome of burning pain, tingling, and extreme sensitivity in affected dermatome.

  • Most frequently affected dermatomes: thoracic, cervical, trigeminal, and lumbosacral
      - Rash develops into vesicular eruptions (rash/exanthem), unilaterally, and usually thoracic

  • Burning and tingling in the area affected by the rash, and extreme sensitivity to touch

    • New groups of vesicles erupt for up to 3-5 days along the nerve pathway

      •Vesicles dry off, form crusts, and eventually fall off    
        - Symptoms may be mistaken for other conditions.
        - Typically clears in 2-3 weeks.

  • Complication: Postherpetic neuralgia (pain > 1-3 months post-rash).
      - Prevalence of Neuralgia: More common in > 60 older adults.

  • Vaccination: Zoster vaccine (Zostavax) recommended to prevent or lessen severity of herpes zoster, with the expectation of increased incidence due to an aging population.

Skin Damage from Ultraviolet Radiation

Overview

  • Role of Skin: The skin acts as a barrier against harmful UV rays.

  • Consequences: Exposure can lead to skin cancers, early aging, and other skin disorders.

  • Types of UV Radiation: measured by nanometers
      - UVC: Shortest wavelength; does not penetrate the earth’s atmosphere but harmful.
      - UVB: Known as “sunburn rays”; responsible for photoaging, pigment changes, and skin dryness
      - UVA: Includes short-wave and long-wave types; associated with skin alterations and present in tanning beds.
      - Source: (Hight, 2024, p. 1537)

Effects of UV Radiation

  • Acute Effects: Immediate effects from UVA and UVB exposure include erythema, skin pigmentation changes, and injury to Keratinocytes and Langerhans cells.
      - UVA-Induced Erythema: Occurs immediately while fading within hours (heat load).
      - UVB-Induced Erythema: Has a delayed response, peaking 6-24 hours post exposure.

  • Tanning Response: Tanning occurs through increased melanocyte activity, which provides some protection against further UV exposure.
      - However, tanning from UVA exposure offers limited protection compared to UVB exposure.

Chronic Damage and Carcinogenic Effects

  • Long-term Damage: UVB exposure leads to reactive oxygen species generation and damages melanin, leading to photoaging.

  • Solar Elastosis: Characterized by abnormal elastotic material accumulation in the upper dermis, leading to skin thickening and loss of elasticity, causing deep, coarse wrinkles.

  • Carcinogenesis: Both UVA and UVB are carcinogenic, with UVA potentially more damaging due to its ability to penetrate deeply.

  • §UVA → less sunburn: present year-round during all daylight hours; penetrate deeper and → greater keratinocyte damage (where skin cancers arise)—in contrast to UVB varying by season, location, and time of day

Thermal Injuries

Overview

  • Statistics: Approximately 490,000 individuals in the US require medical care for thermal injuries annually; 40,000 require hospitalization.

  • Consequences of Thermal Injury: Thermal injuries result in significant integumentary tissue loss, exposing individuals to environmental pathogens, leading to:
      1. Loss of body fluids
      2. Temperature regulation issues
      3. Compromised immune system response
      4. Increased metabolic and reparative demands for recovery

Sources of Burns

  • Types of Burns:
      - Flame Burns: From direct fire exposure.
      - Scald Burns: Resulting from hot liquids; significant in children—may be indicative of child abuse.
      - Chemical Burns: Often due to industrial agents in occupational settings.
      - Electrical Burns: Generally more extensive due to internal damage.
      - Other Sources: Lightning, electromagnetic, and ionizing radiation can also lead to skin burns.

Classification of Burns

  • Types Based on Depth of Involvement:
      - First-Degree Burns: Only the outer layers of the epidermis affected.
      - Second-Degree Burns: Involves the dermis and epidermis.
      - Third-Degree Burns: Extends deeper, affecting subcutaneous tissue.

First-Degree Burns

  • Description: Superficial partial-thickness burns affecting only the outer skin layer.

  • Appearance and Symptoms: Red or pink, dry, and painful with no blister formation (e.g., mild sunburn).

  • Skin maintains its ability to function as a water vapor and bacterial barrier

  • Healing Time: Typically heals in 3-10 days without requiring extensive treatment, although certain populations may require additional care.

  • Healing→ managing pain, hydrate

  • Extensive first-degree burns in infants, older adults, and immunocompromised individuals may require additional care

Second-Degree Burns → very common

  • Partial Thickness: Involve the epidermis and varying depths of the dermis.

    • Characteristics: Painful, moist, red, and blistered appearance.

    • Sensitive to temperature changes, air exposure, and touch

    • Healing Process: Usually 7-21 days; blisters help retain moisture and promote healing.

    • oMain goal of treatment: prevent microbial colonization of the wound

      oSecond-degree partial thickness burns heal in ≈ 7-21 days → KNOW THIS

  • Full Thickness: Involving the entire epidermis and dermis

    • Can be very painful because the pain sensors remain intact

    • Appearance: mottled pink, with red or waxy white areas covered with blisters and edema

      •Blisters resemble flat, waxy, or dry tissue paper rather than the bullous blisters seen in second-degree partial-thickness burns

  • Healing: Timeframe can extend longer than one month, typically leads to scar formation.

Third-Degree Burns → full thickness

  • Description: Extend deeply into the subcutaneous tissue, potentially involving muscle and bone.

  • Appearance: Can be waxy white or yellow to tan to deep brown, deep red or black; with hard and leathery skin.

  • Severe edema

  • Pain Sensation: Typically absent due to destroyed nerve endings, wider than 1.5 inches →requires skin grafts for extensive damage.

  • Regeneration: Slower healing process, resulting in significant scarring.

Systemic Complications Associated with Burns

Overview

  • Response Magnitude: The systemic response correlates with the injury extent, usually plateauing when around 60% of the body is affected.

  • Associated Complications: Include infection, hemodynamic instability, respiratory dysfunction, hypermetabolic response, and multiple-organ dysfunction

Hemodynamic Instability

  • Initial Effects: Immediate injury leads to fluid loss and hypovolemic shock, known as burn shock, especially in major burns.

  • Relevant Concerns: Need for immediate prompt medical intervention includes addressing cardiovascular concerns due to electrical burns or internal damage.

    • oElectrical injuries →  burns can → cardiac arrhythmias requiring immediate attention

Respiratory System Dysfunction

  • Causes of Injury: Inhalation of smoke and possible thermal injury from burns can damage respiratory passages.

  • Signs of Injury: Hoarseness, drooling, coughing, and respiratory distress usually present after 24-48 hours after sustaining burns.

  • Potential Outcomes: Conditions may include pneumonia, pulmonary embolism, or pneumothorax.

Hypermetabolic Response

  • Increased Needs: The stress associated with burns raises metabolic rates and nutrient requirements for recovery and thermoregulation.

  • Hormonal Changes: Elevated secretion of catecholamines and cortisol to maintain physiological balance, peaking in the post-burn state.

  • Metabolic Features: Increased oxygen consumption, glucose utilization, and fat and protein wasting occur as part of this response.

  • Burn shock → impaired function of vital organs

    oAffected individuals may experience renal, GI tract, and nervous system impairment
      

Sepsis

  • Primary Concern: Significant risk factor in burn injuries—greater susceptibility to bacterial infections due to compromised skin barrier.

  • Sources of Infection: Affected individuals may experience infections from various sources including pneumonia, urinary tract infections, and invasive medical procedures due to loss of skin integrity.