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.