Microbio Week 8 - Other Mycoses (Mini Exam) Flashcards
The greater the degree of immunocompromise, the more…
Invasive
What are the 3 hyphal molds?
Aspergillus
Mucor
Dermatophytes
What are the 3 dimorphic fungi?
Histoplasma
Blastomyces
Coccidioides
What is the 1 yeast?
Cryptococcus
Where do most fungi grow? How are they acquired?
Environment
Airborne dust containing spores
What is the morphology of Aspergillus?
Filamentous mold
Septate hyphae (has cross walls)
Branching at 45 degree angle
How does Aspergillus and Mucor reproduce?
Release spores from hyphae into air (airborne)
Where can Aspergillus and Mucor grow?
Outside = on living & decaying organic matter
Inside = on damp, wet surfaces
What are Aspergillus infections caused by?
Inhaling spores
What is one of the most common causes of invasive fungal infections?
Aspergillus
Which is more invasive: Aspergillus or Mucor?
Mucor
How do you diagnose Aspergillus and Mucor infections?
Direct microscopic exam - 10% KOH or silver stain
What are you looking for when doing a direct microscopic exam for Aspergillus infection?
Septate hyphae w/ 45 degree branching
What are you looking for when doing a direct microscopic exam for Mucor infection?
Aseptate hyphae w/ 90 degree branching
What is the response to treatment for Aspergillus dependent on?
of neutrophils
Competence of immune system
Number of neutrophils
What is the key treatment of Aspergillus?
Voriconazole
(must be 100% sure its Aspergillus before treating with Voriconazole)
What is infection by Mucor called?
Mucormycosis
What does Mucor invade?
Major blood vessels (angioinvasion)
(Aspergillus does this as well, but to a less extent. Mucor is the main angioinvasive mold)
What does Mucor angioinvasion lead to?
Black pus + black necrotic tissue
What is the most common pathogen of the Mucor group? (ON EXAM)
Rhizopus
What is the morphology of Mucor?
Filamentous mold
Large diameter, aspetate hyphae
90 degree branching
What are the 2 things that can cause Mucor infections?
Inhaling spores
Spore implantation into tissue
What patients are at high risk for Mucor infection?
Uncontrolled diabetes + ketoacidosis
Cancer (especially those w/ low neutrophils)
What mucor infection can have oral manifestations such as black necrotic lesions on hard palate?
Rhinocerebral mucormycosis
What is the key treatment for Mucor infection?
Aggressive surgical methods
What enhances the virulence of Mucor?
Voriconazole
(this is why its so important to make sure it is Aspergillus before treating with Voriconazole!!!)
Where do Histo, Blasto, and Coccidio infect?
Respiratory tract
T/F: Oral manifestations of Histo, Blasto, and Coccidio are very common
FALSE, oral manifestations are rare, but may be seen in immunocompromised
What are the diseases caused by Histo, Blasto, and Coccidio restricted to?
Defined geographical areas
Histo, Blasto, and Coccidio are all ___________ dimorphic
thermally
Where are Histo, Blasto, and Coccidio seen as filamentous mold?
Soil
Where are Histo, Blasto, and Coccidio seen as yeast with budding?
Body tissues
Which dimorphic fungi is an exception because it does NOT form a traditional yeast, but instead forms a structure called a spherule that contains endospores?
Coccidio
Habitat for Histo
Bird and bat droppings
Habitat for Blasto
Organic matter (rotting wood, animal droppings, plants)
Habitat for Coccidio
Fine sand and silt
Transmission for Histo and Blasto
Inhaling spores -> becomes yeast during infection
Transmission for Coccidio
Inhaling spores -> becomes spherules during infection
Common geographical area for Histo
Ohio and Mississippi river valleys + Louisville
Common geographical area for Blasto
Ohio, Mississippi, Missouri, and Arkansas river valleys + Louisville
Minnesota and Wisconsin
Common geographical area for Coccidio
Hot, arid Sonora desert region of Southwestern US
Cali, Arizona, New Mexico, Texas
Parts of Mexico in San Joaquin valley
What diseases of Histo, Blasto, Coccidio contribute to the oral manifestations?
Disseminated diseases
How do you diagnose Histo, Blasto, Coccidio?
Direct microscopy exam - 10% KOH or silver stain
What are you looking for when diagnosing Histo, Blasto, Coccidio using direct microscopy exam?
Histo yeast -> narrow bud
Blasto yeast -> broad based bud
Coccidio spherule -> sac filled with spores
Which yeast has a capsule?
Cryptococcus
How is Cryptococcus different from traditional yeast?
It produces a polysaccharid capsule
How is the most common species of Cryptococcus transmitted?
Inhaling yeast from exposure to pigeon droppings
When does Cryptococcus have oral manifestations particularly in the immunocompromised?
Disseminated forms
How do you diagnose Cryptococcus?
India ink stain (allows you to see capsule)
Do Dermatophytes have oral manifestations?
NO, but it may be expressed on facial surface
Where are Dermatophyte infections found?
Superficial skin, hair, nails (“tinea”)
What is the major virulence factor of Dermatophytes?
Keratinase
What does keratinase degrade in Dermatophyte infections?
Skin, hair, nails
What are the 3 species of Dermatophytes?
Trichophyton
Microsporum
Epidermophyton
Trichophyton morphology
Cigar-shaped macroconidia
Many microconidia
Microsporum morphology
Rough, spindle-shaped macroconidia
Some microconidia
Epidermophyton morphology
Smooth, club-shaped macroconidia
NO microconidia
How are Dermatophytes transmitted?
Direct via contact with spores (infected tissue, soil)
Indirect transmission via contaminated surfaces/objects (hairbrush, comb, carpet)
Tinea capitis lesion location
Scalp (hair/skin)
Tinea faciei lesion location
Non-bearded parts of face
Tinea barbae lesion location
Beard, mustache, neck
Tinea corporis (ringworm) lesion location
Body (trunk, arms, legs)
Tinea manuum lesion location
Palms, fingers
Tinea pedis (athletes foot) lesion location
Soles of feet, between toes
Tinea unguium lesion location
Nails (toes more common than fingers)
