Lecture 47: Fungi SBM Flashcards
1
Q
White Piedra
![](https://s3.amazonaws.com/brainscape-prod/system/cm/114/355/135/q_image_thumb.jpg?1659487254)
A
- superficial infection caused by Trichosporon
- part of spore-forming Anthrocondia
- can infect cutaneous tissue
- can disseminate systemically
- Sx of white piedra
- asx growth on outside of hair shaft, white, green, or yellowish soft nodules
- Rx: shaving and antifungals
- amphotericin B
- all azoles
2
Q
Black Piedra
![](https://s3.amazonaws.com/brainscape-prod/system/cm/114/356/350/q_image_thumb.jpg?1659487261)
A
- caused by ascomycete genus Piedraia spp
- Asx but visible colonization of shaft of scalp hair
- disorder restricted to tropics
- Rx: difficult, azoles w limited success
3
Q
Tinea nigra
![](https://s3.amazonaws.com/brainscape-prod/system/cm/114/357/107/q_image_thumb.jpg?1659487265)
A
- don’t confuse w black piedra on hair
- Tinea nigra caused by Hortae werneckii (Exophiala werneckii)
- brown-black lesion on hands and feet; pigmentation more intense at borders; no invasion of living tissue only outer dead layers of skin
- colonies are smooth w oily glistening, olive-black colour
4
Q
Pityriasis versicolor aka Tinea versicolour
![](https://s3.amazonaws.com/brainscape-prod/system/cm/114/357/705/q_image_thumb.jpg?1659487269)
A
- Pityriasis versicolor caused by Malassezia furfur
- infects all layers of stratum corneum
- Sx: usually superficial, chronic, and asx
- macular rash or fine scaling of upper trunk and shoulders
- Dx: skin scraping and microscopy
- M. furfur morphology of both filaments and yeast (spaghetti and meatballs)
- Rx: antifungals
![](https://s3.amazonaws.com/brainscape-prod/system/cm/114/357/705/a_image_thumb.jpg?1659434538)
5
Q
Other infections w Malassezia spp
![](https://s3.amazonaws.com/brainscape-prod/system/cm/114/358/394/q_image_thumb.jpg?1659487270)
A
- opportunistic systemic infections via central venos catheters
- may cause seborheic dermatitis & dandruff
- Dx: yeast isoltion on lipid-containing media
6
Q
Cutaneous mycoses: Dermatophytes
A
- commonly called ring worm and jock itch
- fungi using keratin as nutrient source -> colonize keratized stratum corneum only
- Sx: typical skin lesion
- annular. scaly pathc w raised margin
- infection of hair causes hair loss and dry, scaly patch of skin
- nails become yellow, thickened, and cracked
- Predisposing conditions to chronic infection
- nl person w minor immunological blind spots
- old age
- collagen vascular disease
- diabetes
- hematological malignancy
- 3 sources of infection: humans, zoonotic, soil
7
Q
Microsporium
![](https://s3.amazonaws.com/brainscape-prod/system/cm/114/359/522/q_image_thumb.jpg?1659487271)
A
- attack skin and hair but NOT NAILS
- microsporum form both macroconidia & microconidia
8
Q
Epidermophyton spp
![](https://s3.amazonaws.com/brainscape-prod/system/cm/114/447/803/q_image_thumb.jpg?1659487401)
A
- Epidermophyton attacks skin & nails but does NOT invade hair
- E. floccosum is the onl pathogenic spp
- macroconidia w smooth walls
- born-singly or in banana-like clusters
- microconidia abset
9
Q
Trichophyton spp
![](https://s3.amazonaws.com/brainscape-prod/system/cm/114/450/678/q_image_thumb.jpg?1659487405)
A
- Trichophyton attack skin, hair, and nails; noted for lifelong nail infection.
- microconidia > macroconidia
- T. mentagrophytes, rubrum, tonsurans (major cause of ringworm in skin)
10
Q
Clinical forms of dermatophyte infection
A
- infections caused by dermatophytes clinically classified on basis of location of lesions on body
11
Q
Tinea corporis
A
- ringworm involving trunk, shoulder, axilla, chest, and back
- lesions are well marginated w raised erythematous, vesicular bordrs
- most serious chronic infection due to T. rubrum
12
Q
Tinea cruris aka Jock itch
A
- frequently caused in adults by T. rubrum & E. floccosum
- sx: lesions are erythematous, scaly, raised inflamed borders, often w vesicles
- itching/burning
13
Q
Tinea capitis
![](https://s3.amazonaws.com/brainscape-prod/system/cm/114/456/966/q_image_thumb.jpg?1659487417)
A
- Ectothrix invasion when fungus forms sheath of hyphae and arthroconidia around shafts of hair.
- Microsproum spp. common causes
- Endothrix invasion when hyphae invade hair follicle and shaft and form many spores w/in hair shaft
- infected grayish-white hairs break off easily at scalp giving black dot apperance.
- Trichophyton tonsurans common cause
14
Q
Tinea pedis
![](https://s3.amazonaws.com/brainscape-prod/system/cm/114/458/188/q_image_thumb.jpg?1659487418)
A
- sx: scaling, fissuring, erythema, itching, and burning
- acute condition characterized by vesicles, inflammation, and pustules (sterile)
- T. mentagrophytes, T. rubrum, E. floccosum common causes
15
Q
Tinea barbae
A
- zoonotic Triphyton spp. common causes
- T. verrucosum: cattle
- T. mentagrophytes: mice & rodents