Medically Relevant Fungi Flashcards
Blastomyces dermatitidis
- Clinical presentation
Clinical Presentation
- Presents as nonspecific febrile acute or chronic pulmonary disease mimicking community-acquired pneumonia
- Ultimately disseminates, involving
- cutaneous
- genitourinary
- bony
lesions
Candida spp.
Causes candidemia (candida in the blood)
- Typically causes disease only in people who are immunocompromised
Candida spp.
- Overivew
- Where it’s found
- Aetiologies of infection (4)
- NORMAL FLORA of the GI TRACT
- Often colonized in the skin and environment
- Typically only infects the immunocompromised
Aeteologies
1. Diaper rash
- Breakdown of the skin from fluids can allow infiltration and cause infection
- Vaginits MOST COMMON
- Candida is the normal flora of the GI tract
- Women tend to get these infections due to the shorter perineum
- - Opportunistic Infections
- Antibiotic use kills off competing bacteria - Oral Thrush
- Overgrowth on the tongue or oropharynx
- Tend to see it in radiation/chemo PTs, low CD4 counts
Coccidioides immitis
- Clinical Presentation
Clinical presentation
- PULMONARY involvement and in most cases ASYMPTOMATIC
- Symptomatic infection presents with
- FEVER
- COUGH
- CHEST PAIN
Often mimics community-acquired pneumonia
DISSEMINATED and can occur locally with
- pleural
- pericardial
invasion, or ANY ORGAN of the body
Disseminated presentation can also involve
- Cutaneous
- Genitourinary
- Bony lesions
Cryptococcus spp.
Yeast
- Virulent pathogen that can lead to cryptoccocemia
- Also a major cause of meningitis
Cryptococcus Spp.
- Two Species
- Cryptococcus neoformans
- Found in soil, but is concentrated in bird guano
- In major cities, typically found in dried pigeon feces
- Urea and warm, moist environment promote growth - Cryptococcus gattii
**Neither typically cause disease unless the host is immunocompromised, OR THE BURDEN IS VERY HIGH
Cryptococcus Spp. - Overview
- Where it’s found
- What it can cause
- Structural Feature
YEAST
- Typically do not cause infection unless there is an underlying comorbidity or PT is immunocompromised
- Found in soil, dried animal faces (specifically bird poop)
- Can cause pneumonia, fungemia (disseminated), meningitis, and cutaneous infection
- Large capsule around the yeast cell, helps it evade immune-mediated phagocytosis
-
Cryptococcus World Event
- Vancouver hurricane, rooted up soil in parks and aerosolized it, several months later there were outbreaks of cryptococcus meningitis
Dermatophytes
MOLD
- Skin loving mold
- Produce skin infections
- RING WORM
Dermatophytes
- Common Infections
- Three genus + what they infect
- Ring worm
- Athlete’s foot
Three Genus:
1. Trycophyton (hair, skin, nails) “tri”
2. Epidermophyton (skin, nails)
3. Microsporum (skin, hair)
Dermatophytes
- Type
- Type of infection
- Special product
MOLD
- Distinct group that only infect hair, skin, nails
- Produce keratinase enzyme which breaks down keratin (found in hair, skin, nails)
Dimorphic Fungi
MOLD
- Can lead to disease in NON immunocompromised hosts
- The likelihood of infection is based solely on the amount of exposure
Dimorphic Fungi
MOLD
- Can cause clinical disease in the immunocompromised
TEMPERATURE-DEPENDENT DIMORPHISM
- Yeast at 37 C
- Mold at 25 C
So when it infects humans, it infects as a YEAST
but naturally in the environment, it exists as a MOLD
Dimorphics: Coccidioides immitis and Paracoccidioides brasilensis
- Geographic range
Coccidioides
- Very geographically limited
- Found only in CA, NV, AZ
- In sand
Paracoccidioides
- Brazil
Dimorphics: Histoplasma capsulatum and Blastomyces Dermatiditis
- Geographic Range
Histoplasma
- Lives globally, found all throughout the world fairly evenly and ubiquitously
Blastomyces
- Unique in its geographic range
- Hot bed areas include
- MA
- NY
- Kingston
- Northern Ontario
- Montreal
Essentially along the St. Lawrence valley
Dimorphics: Sporothrix Schleferi and Taloromyces marneffei
- Geographic Range
Sporothrix
- Most commonly found near plants
- Called “rose grower’s fungus”
- Found on thorns of roses, puncture wounds often lead to infection
Taloromyces
- Vietnam, Laos, Thailand
- Stays ‘quiet’ and can reactivate when PT becomes immunocompromised
Four Relevant Molds
- Dermatophytes
- Zygomycetes
- Hyaline Molds
- Dimorphic Fungi
Highland Molds
MOLD
- Tend to be environmental
- Break down environmental tissue, tend to be found in areas with lots of detritus
Histoplasma capsulatum
- Type
- Clinical presentation
DIMORPHIC FUNGI
Clinical presentation
- Fever
- Sweats
- Fatigue
- Weight loss
- CNS involvement in 5-20% of acute disseminated histoplasmosis presenting as chronic meningitis
Medically Relevant Molds
- Dermatophytes
- Zygomycetes
- Hyaline molds
- Dimorphic Fungi
Mucomorales (Zygomecetes) Molds
- Key difference between zygomecetes and other mucomorales molds
Most mucomorales molds tend to grow “down”, meaning that they spread along blood vessels leading to necrosis
Zygomecetes however tend to travel “inward”, meaning that they tend to penetrate deep tissue, travelling from the site of infection (eg the sinuses) towards the center (orbit, brain)
extremely aggressive disease as the organism does not repeat tissue planes, often leading to devastating rhino-orbital infections and wound infections
Mucomorales (Zygomecetes) Molds
- Structure
- Found in
- A fast growing fungi characterized by continuous tubes made up of cytoplasm and multiple nuclei
Found in soil, dung, and vegetative matter
Mucomorales (Zygomecetes) Molds
- Unique characteristic
Known as ‘lid lifters’
- Their hyphae rapidly grow upward and produce spores which are then released, lid must be taped.
Opportunistic Fungi (5)
- Aspergillus
- Penicillium
- Paeciliomyces
- Acremonium
- Fusarium
