Week 32 Fungal infections copy

Fungal Infections

• Definition: Fungal infections, also known as mycoses, are infections caused by fungi that can affect humans.

Overview of Fungi

• Classification

  • Eukaryotes occupying their own kingdom, distinct from plants and animals.

  • Types of Fungi:

    • Molds: Filamentous fungi with hyphae, reproduce using spores.

    • Yeasts: Unicellular, often round or oval, reproduce by budding.

  • Approximately 7,000 different types exist, with 300 identified as human pathogens.

Classifying Fungi

• Growth Forms:

  • Filamentous Fungi:

    • Characterized by a mass of hyphae (mycelium).

    • Asexual reproduction by forming sporangia, containing spores.

    • Spores are a common transmission method, especially when inhaled.

  • Yeast-like Fungi:

    • Single cells replicating by budding; can form chains (pseudohyphae).

    • Can exhibit dimorphic forms dependent on temperature.

Types of Mycosis

• Classification of Fungi (Groups):

  • Obligate Parasites:

    • Attack external structures (skin, nails, hair) predominantly dermatophytes.

    • Filamentous

    • Mass of hyphen form= mycelium

    • Asexual reproduction results from formation of sporangia- sacs that contain and release spores

    • Spores common transmission if inhaled lead to infection

    • Yeast Like

    • Single cell that replicate by budding

    • Buds can stay attached leading to chains caused by pseudohyphea

  • Soil Fungi:

    • Adapted to harsh environments, tolerant of high temperatures; also dimorphic.

  • Opportunistic Saprobes:

    • Generally only affect compromised immune systems.

  • Fungi are ubiquitous, found in soil, water, and living organisms.

  • Mycosis: Fungal infections; varying transmission methods include inhalation, trauma, and ingestion.

  • 3 groups: Obligate parasites - live in hair nails skin usually dermatophytes they attack external structures

  • Soil fungi - found in the soil but have been able to adapt to hostile environments in the human body they are dimorphic

  • Opportunistic saprobes - usually attack when immune system has been compromised or is artificially suppressed example organ transplant

  • Fungi and their spores are found almost everywhere in the environment example wood, glass, plastic ,metal ,soil water on and or multi organisms like plants and animals

  • Most mycoses are not contagious except for dermatophytes.

  • Mycosis

  • Acquired by inhilation, trauma or ingestion

  • Rare case of person to person transmission

  • Meaining they are not contagious but from exposure to environment

  • One group of fungi are contagious is dermatophytes

Factors Predisposing to Mycoses

• Medical Procedures: Surgeries, catheterization.

• Medical Treatments: Immunosuppressive therapies, cancer treatments, steroids.

• Diseases: Inherited immune defects, AIDS, diabetes, severe burns, leukemia.

• Lifestyle Factors: Malnutrition, poor hygiene, IV drug use.

Pathogenic versus Opportunistic Fungi

• Pathogenic Fungi: Cause disease regardless of immune status.

• Opportunistic Fungi: Typically infect individuals with compromised immune systems.

• Dermatophytes can infect everyone but are generally confined to body surfaces.

Types of Infections (Mycoses)

• Classifying Infection Types:

  • Superficial Mycoses: Affect hair shafts, dead skin layers.

  • Cutaneous Mycoses: Affect epidermis, hair, nails.

  • Subcutaneous Mycoses: Affect dermis and subcutis.

  • Systemic Mycoses: Affect internal organs.

  • Opportunistic Mycoses: Affect immunocompromised patients.

Transmission of Fungal Infections

• Superficial Infections: Can spread human-to-human or animal-to-human.

• Subcutaneous Infections: Spread through skin penetration (e.g. twigs, thorns).

• Deep Infections: Often affect the immunocompromised.

• Free-living fungi may cause immune reactions; toxins produced can be harmful (mycotoxins).

Important Fungal Diseases**

• Superficial:

• The most common infection fungal infections = outer, dead layers of skin, nails and hair

• These cells are filled with keratin- protein

• Primary food for the fungi

• Dermatophytes thrive here

• Keratin loving organisms

• Adhere

• Germinate

• Invade

  • Infections: Pityriasis versicolor, piedra.

  • Organisms: Trichosporon, Malassezia, Exophiala.

• Cutaneous:

  • Infections: Tinea (ringworm). Form annular scaling patch with a raised margin which is incredibly itchy

  • Organisms: Microsporum, Trichophyton, Epidermophyton.

• Subcutaneous:

  • Infections: Sporotrichosis, mycetoma.

  • Organisms: Sporothrix and others.

• Systemic:

  • Infections: Coccidioidomycosis, histoplasmosis, blastomycosis.

  • Organisms: Coccidioides, Histoplasma, Blastomyces.

• Opportunistic:

  • Infections: Cryptococcosis, candidiasis, aspergillosis.

  • Organisms: Cryptococcus, Candida, Aspergillus.

Laboratory Diagnosis

• Dermatophytes fluoresce under UV light as a diagnostic aid.

• Scraping or clippings from lesions cultured on Sabouraud dextrose agar (SDA) to identify.

• Common treatments include topical antifungal creams, e.g., miconazole.

Candidiasis

• Thrives in moist environments; often requires damaged or moist skin to proliferate.

• Common forms: Oral thrush (white patches), vaginal thrush (itching, inflammation), skin/nail infections in folds.

• Diagnosis similar to dermatophytosis; includes Specimens from skin/nails and swabs.

Systemic Fungal Infections

• Aspergillosis: Caused primarily by A. fumigatus and A. flavus. Inhalation can cause severe disease in immunocompromised. Of >200 species less than 20 are implicated in human disease

• Inhalation of certain species can cause localized lung infection of health individuals

• Life threatening for immune compromised individuals have a mortality rate of 50-100%

• Allergic aspergillosis- cause inflammation in the sinus’s

• Invasive aspergillosis

• Widespread destructive growth in lung tissue along with blood vessels cause thrombosis causing spread to other organs

• Diagnosis involves microscopy sputum is prepared by hydrogen peroxide , culture (colonial appearance), and possibly imaging (x-rays or CT scans)

• Treatments vary significantly, including antifungal medications; treatment needs to be prompt due to high mortality rates.

Mycetoma (Madura Foot)

• Chronic granulomatous infection from soil fungi requiring traumatic introduction.

• Clinically presents as painless masses, potentially leading to destruction of underlying tissues.

• Requires both antifungal treatment and probable surgical intervention; diagnosed through the presence of grains in pus.

Case Study: Candida auris

• An emerging yeast causing severe infections in hospitalized patients; multidrug-resistant.

• Can spread rapidly, especially in healthcare settings; presents diagnostic challenges due to misidentification issues.

Toxic Effects of Fungi

• Potential to cause mycotoxicosis (toxicosis from mycotoxins from consumption) or mycetismus (mushroom poisoning).

• Amanita phalloides: Known as the death cap, produces lethal toxins. Symptoms include severe gastroenteritis leading to multi-organ failure.

Summary

• Types of Fungal Infections: Superficial, systemic, subcutaneous infections, with examples like Tinea, Candida, Aspergillus, and Mycetoma.

• Understanding transmission and classification of fungi is key to prevention and treatment of fungal infections.