Superficial and Cutaneous Mycoses Flashcards
What causes mycoses
Yeasts for the most part
What causes Pityriasis Versicolor
Malassezia Furfur
What does Pityriasis Versicolor look like
Hypo or hyper pigmented macules on chest, neck, back
What immune responses do we typically see to Superficial Mycoses?
Little to no immune response
Where do superficial mycoses colonize?
Outer keratinized surface of skin, hair, or nails
What causes dandruff?
Malessezia Globosa
How do we diagnose a superficial mycosis?
Direct visualization of yeast-like cells and short branched pseudohyphae.
Treatment for superficial mycosis?
Topical therapy, olive oil, single dose oral azole if widespread
What makes a cutaneous mycosis different from a superficial one BASICALLY?
Cutaneous involves invasion of the epidermis with an inflammatory response. They break down keratin after invading the stratum corneum.
What primarily causes cutaneous mycoses?
Mold dermatophytes such as trichophyton, epidermophyton, and microsporum
What does microsporum typically cause?
Athlete’s foot, jock itch, ringworm
Tinea infections
Latin for “worm”
Caused by dermatophytes. Result in inflammatory scaling often in the pattern of an expanding circle or ring with frequent hair loss
Tinea capitis
Tinea infection of the head
Tinea Coporis
Trunk of the body
Tinea Barbae
Tinea of the face
Tinea Cruris
Tinea inguinally
Tinea pedis
Tinea of the foot
Normal treatment for tinea?
Topical anti-fungal treatment. When hair or nails are involved, oral antifungal treatment is usually necessary.
How do we diagnose Tinea?
Microscopy/culture
Subcutaneous Mycoses
Invade the subcutaneous fat. This is rare, usually induced by trauma and often has a slow progression requiring surgery.
Spreading pattern of subcutaneous Mycosis
Laterally, not to distant organs
Sprotrichosis is caused by what
sporothrix schenckii transmission. This is a dimorphic fungi found in soil and vegetation. Penetrated epidermis will permit growth via a yeast form of this.
Symptoms of a sprotrichosis mycosis infection
Usually starts as a small nodule that ulcerates and becomes painful. 2-3 weeks later secondary lesions along lymphatics progress proximally (sporotrichoid spread- other diseases exhibit a similar “spread”).
Diagnosis of Sprotrichosis mycosis
Biopsy. Can establish genus and species from culture
Treatment of Sprotrichosis Mycosis
Intraconazole orally - can take several weeks
How do we typically get Sprotrichosis mycoses?
Inhalation typically
Chromomycosis
Found in the tropics, this is an opportunistic fungus
What is a granulomatous infection?
Result of an opportunistic subcutaneous fungal infection. They emerge out from the subcutaenous tissue and emerge outward. They form medlar bodies
How do we treat subcutaneous mycoses?
Very difficult, usually try azoles long term
Eumycotic mycetoma
Caused by a variety of fungi in the soil entering wounds. Causes a deep subcutaneous fungal infection that results in gross localized swelling with underlying sinus tracts. Granulomas can develop with granule formation and pus
Fungi that can cause Eumycotic mycetoma
Madurella (most common) Fusarium Acremonium Exophiala Scedosporium
What eumycotic mycetoma do we find in trench warfare?
Madurella
How do we diagnose Eumycotic mycetoma
Detection of granules by gross visualization or microscopy
How do we treat Eumycotic mycetoma
Antifungal agents and local surgery. Treatment is usually not effective. Frequent cure is amputation
Discuss microscopy as it is used to diagnose fungal infections: 10% KOH Tests
10% KOH tests are typically done on skin scraping. If you think cutaneous fungal infection, you may do this. KOH dissolves away keratinocytes and you may see fungal elements
Discuss microscopy as it is used to diagnose fungal infections: Calcofluor white
Calcofluor white (generally a go to stain) is a fluorescent dye which binds to fungal walls
Discuss microscopy as it is used to diagnose fungal infections: India Ink
o India ink (not as popular) used on CSF to look for Cryptococcus (has a large suger capsule. It shows as a halo under india ink
Discuss microscopy as it is used to diagnose fungal infections: Methenamine Silver
There are a number of silver stains. This is fairly popular.
Why is culture is considered the gold standard for detecting fungi
- More sensitive than microscopy
- Allows for ID via mycelium appearance or presence of asexual spores (genus and species)
- Usually grown on Sabouraud’s agar – designed to inhibit bacterial growth
- Most fungi can grow in standard blood culture bottles
What is mycology
Study of fungi
What type of organism is a fungus?
Fungi are eukaryotic, uni or multicellular, non-photosynthetic, and have chitin and glucan cell walls.
What is a good medicinal target structurally on the fungus?
Fungal membrane contains ergosterol (mammal cell walls contain cholesterol so ergosterol is a good medicinal target
Different types of general fungi?
They consist of yeasts (unicellular), molds (multicellular), or can be both (dimorphic).
Are fungi aerobic or anaerobic?
Aerobic typically
How do yeast multiply
Binary Fission
Budding (typically the route they take)
What are hyphae and where do we find them?
Molds grow apically and branch via hypae (branches). At the hyphae, molds can grow spores.
What are septa and where do we find them?
Hyphae have septa that have pores that allow communication and nutients vs. discrete cells.
How do fungal spores reproduce?
Most fungal spores reproduce through mitosis (asexual) although some are sexual and reproduce via meiosis.
Can Neutrophils combat fungi? If so how?
Neutrophils fight extracellular molds such as aspergillus and release defensins to fight them
