Chapter 19_AFernando.pptx

Page 1: Microbiology and Diseases by Body System

Introduction

• Microbial Diseases of the Skin and Wounds presented by Robert W. Bauman (2012)

• Lecture prepared by Mindy Miller-Kittrell

Page 2: Anatomy Review

Skin Structure

• Layers of Skin:

  • Epidermis: Outer layer, dead and impenetrable.

  • Dermis: Beneath the epidermis.

Functions of Skin

• Prevents excessive water loss.

• Regulates body temperature.

• Involves sensory phenomena.

• Acts as a barrier against microbial invaders.

• Contains a salty surface.

• Hosts normal flora, including halophiles resistant to sebum.

Page 3: Normal Flora

Skin Microbiota

• Generally harmless but cannot be completely removed through cleansing.

• Composed of:

  • Yeasts: e.g., Malassezia, causing itchy pimples.

  • Bacteria: e.g., Staphylococcus, Micrococcus, diphtheroids.

• Can cause disease if they breach the epidermis or if the immune system is compromised.

Page 4: Wounds

Overview of Wounds

• Trauma to body tissue, e.g., cuts, scrapes, surgery, burns, bites.

• Allows microbes to infect deeper tissues.

• Body defenses often eliminate infection, but severe or fatal diseases can result.

Page 5: Folliculitis: Signs and Symptoms

Infection Types

• Infection of hair follicles often called a pimple.

• If at eyelid base, referred to as a sty.

• Spread can lead to:

  • Furuncles (boils)

  • Carbuncles (multiple furuncles growing together).

Page 6: Folliculitis Images

Clarifications

• Images depict types of folliculitis, including carbuncles and furuncles.

Page 7: Folliculitis: Pathogens & Virulence

Causative Agent

• Staphylococcus: Gram-positive, facultative anaerobes, cocci in clusters.

• Salt-tolerant and can survive desiccation (>600°C for 30 min).

• Two common species:

  • Staphylococcus epidermidis

  • Staphylococcus aureus (more pathogenic)

Differences Between Species

• Beta-lactamase production and toxin production distinguish them.

Page 8: Virulence Factors of Staphylococcal Species

Comparison Table of S. aureus and S. epidermidis

• Details on enzymes, toxins, and proteins affecting virulence:

  • Hyaluronidase, coagulase, and others.

  • Presence of polysaccharide slime layer and protein A that inhibits phagocytosis.

Page 9: Folliculitis: Diagnosis, Treatment, & Prevention

Diagnosis

• Isolation of gram-positive bacteria from pus.

Treatment

• Dicloxacillin: Preferred treatment.

• Vancomycin: For resistant strains.

Prevention

• Hand antisepsis and proper hospital procedures to minimize MRSA infections.

Page 10: Staphylococcal Scalded Skin Syndrome (SSSS)

Pathogen and Virulence Factors

• Strains of Staphylococcus aureus producing exfoliative toxins cause SSSS.

Pathogenesis

• No scarring occurs as the dermis remains unaffected.

• Secondary infections may lead to death, but it's rare.

Epidemiology

• Primarily affects infants; spread via person-to-person contact.

Page 11: SSSS Overview

Illustrative Figure

• How exfoliative toxins affect the skin.

Page 12: Impetigo and Erysipelas

Pathogens and Virulence Factors

• Primary cause is S. aureus, occasionally by Streptococcus pyogenes.

• Pathogenicity includes similar virulence factors (M protein, hyaluronic acid).

Pathogenesis

• Bacteria invade compromised skin; can lead to complications like acute glomerulonephritis.

Epidemiology

• Common transmission through person-to-person contact or fomites.

Page 13: Impetigo Overview

Images

• Clinical pictures of impetigo.

Page 14: Erysipelas Overview

Risk Factors

• Occurs primarily in elderly populations.

Page 15: Necrotizing Fasciitis

Characteristics

• Usually caused by Streptococcus pyogenes (Group A).

• Gram-positive cocci, tissue-invading enzymes, exotoxins damage tissue.

Pathogenesis and Epidemiology

• Enters through skin breaks, spreads person-to-person.

a### Diagnosis, Treatment, and Prevention

• Hard-to-diagnose early due to nonspecific symptoms; treated with clindamycin and penicillin or broader antibiotics.

Page 16: Necrotizing Fasciitis Pathogenesis

Mechanisms of Infection

• Pathogen enters and spreads rapidly; secretes enzymes to invade.

Page 17: Necrotizing Fasciitis Mechanisms

M Protein and Toxins

• M protein helps survive phagocytosis; Streptolysin S and exotoxin A damage tissues.

Page 18: Acne

Characteristics and Pathogen

• Caused by Propionibacterium acnes; a common skin inhabitant.

Epidemiology

• Usually starts in adolescence but can appear later.

Diagnosis and Treatment

• Diagnosed visually; treated with antimicrobial drugs and exfoliants; Accutane for severe cases.

Page 19: Acne Development Illustration

Stages of Acne

• Explanation of pore blockage and inflammation leading to various types of acne.

Page 20: Pseudomonas Infection

Pathogen and Virulence Factors

• Causative agent: Pseudomonas aeruginosa; thrives in moist environments.

Pathogenesis

• Infects burn victims, causes extensive tissue damage.

Diagnosis, Treatment, and Prevention

• Difficult to diagnose; treated with specific antibiotics.

Page 21: Pseudomonas Infection Illustration

Visual Representation

• Image depicting Pseudomonas aeruginosa infections in the skin.

Page 22: Cutaneous Anthrax

Characteristics

• Caused by Bacillus anthracis through breaks in the skin, leads to a black eschar.

Treatment and Prevention

• Treated with antimicrobial drugs; prevention demands animal disease control.

Page 23: Gas Gangrene

Characteristics and Pathogens

• Caused by Clostridium species (e.g., C. perfringens).

• Symptoms include tissue necrosis, blackening skin, and gas bubble presence.

Treatment

• Involves surgical removal of necrotic tissue and antibiotics; prevention focuses on wound cleaning.

Page 24: Diseases of Poxviruses

Overview

• Includes smallpox, orf, cowpox; smallpox was the first eradicated virus.

Diagnosis, Treatment, and Prevention

• Requires immediate vaccination; previously widespread vaccination has been discontinued.

Page 25: Stages of Poxvirus Lesions

Visual Representation

• Illustration depicting the stages of lesions in poxvirus infections.

Page 26: Herpes Infections

Characteristics

• Caused by human herpesviruses 1 and 2; shows slow spreading lesions.

Pathogenesis

• Symptoms stem from inflammation and cell death; can cause syncytia.

Treatment

• Diagnosis by lesions; control medications like acyclovir are available.

Page 27: Herpes Lesions Illustration

Visual Representation

• Shows herpes lesions and related anatomical structures.

Page 28: Herpesvirus Latency

Pathways of Infection

• Displays importance of ganglia in herpes virus latency and recurrence.

Page 29: Chickenpox and Shingles

Characteristics

• Chickenpox: lesions on back and trunk; Shingles: localized lesions along nerves.

Pathogen

• Caused by varicella-zoster virus (VZV); often severe in adults.

Prevention

• Vaccines available for both conditions.

Page 30: Chickenpox to Shingles Pathogenesis

Reactivation of VZV

• Diagrammatic representation of VZV becoming latent and reactivating.

Page 31: Warts

Description

• Benign epithelial growths caused by various papillomaviruses.

Transmission

• Direct contact and fomites; some/onco- strains linked to cancer.

Treatment

• Diagnosed via observation; various removal techniques are available.

Page 32: Rubella (German Measles)

Characteristics

• Occurs mostly in infants; can cause teratogenic birth defects.

Pathogen and Prevention

• Caused by rubella virus, preventable with vaccines focusing on pregnant women.

Page 33: Efficacy of Rubella Immunization

Statistical Overview

• Graph depicting decrease in rubella cases since the introduction of a vaccine.

Page 34: Measles

Characteristics

• Identified by Koplik’s spots and highly contagious nature.

Pathogen

• Caused by the measles virus; diagnosis based on symptoms; prevention through MMR vaccine.

Page 35: Measles Cases in the U.S.

Historical Data

• Graph illustrating the decline of measles cases due to vaccination efforts.

Page 36: Mycoses

Definition and Classification

• Fungal diseases often opportunistic, classified by infection location:

  • Superficial, subcutaneous, systemic.

Page 37: Superficial Mycoses

Symptoms and Pathogens

• Ringworm and other conditions caused by dermatophytes.

Transmission and Treatment

• Shared personal items spread fungi; treated by topical or oral medications.

Page 38: Pityriasis Illustration

Visual Aid

• Image depicting appearance of pityriasis versicolor.

Page 39: Cutaneous Mycoses

Characteristics

• Result from dermatophyte infections, leading to cutaneous lesions.

Diagnosis and Treatment

• Confirmed through KOH preparations; treated with topical or oral agents.