Mycologie Flashcards
Quels sont les signes radiologiques typiques de l’aspergillose pulmonaire invasive?
- Halo sign : macronodule entouré d’opacités en verre dépoli (hémorragie alvéolaire)
- Infarctus pulmonaire wedge-shaped
- Signe du croissant : nodule avec croissant d’air (séquestre mycotique)
- Selon EORTC : Dense, well circumscribed lesion with or without halo sign
- Autres : bronchopneumonie, nodule solitaire/multiples, consolidation lobaire, pneumonie cavitaire ou nécrosante (surtout chez les patients très immunosupprimés non-neutropéniques)
Quels sont les signes cutanés bien connus associés à la candidémie ?
- Lésions macronodulaires de 0,5-1cm roses/rouges
- Echtyma gangrenosum
- Purpura fulminans
- Vasculite leucocytique
What are the dermatophytes causing Tinea corporis? First one on the list is the most frequent.
1 = Trichophyton rubrum
Others :
- T.tonsurans
- Microsporum canis (mainly in children)
- T.mentagrophytes
- M.gypseum
- T.violaceum
- M.audouinii (West Asia, North Africa)
What are the dermatophytes causing Tinea pedis?
-T. rubrum
-T. mentagrophytes
- Epidermophyton floccosum
What are the dermatophytes causing onychomycosis?
1 = T.rubrum
- T.mentagrophytes
- E.flocosum
… And others
What is the organism causing trichomycosis axillaryies?
Trick question! Not a fungus, but species of Corynebacterium - often Corynebacterium flavescens.
- Clinical presentation : yellow-white-black sheath like structures on hair shafts, with malodorous nodules.
- Dx : gram stain of hair shafts has numerous GPB and Corynebacteria will grow on culture.
What causes white Piedra?
Trichosporon species :
-T.ovoides
-T.inkin
-T.cutaneum
Acronyme CIO (comme comité international olympique)
What causes black Piedra and in what parts of the world is it seen?
-Piedraia hortae
-Commonly seen in tropics
What can be the “complications” or “clinically variant presentation” of tinea corporis?
- Kerion (intense pustular reaction 2/2 zoophilic fungi): vraiment plus vu en tinea capitis qu’en corporis
- Majocchi granuloma (intense postulo-papular reaction)
What are the organisms causing tinea capitis?
In North America = T.tonsurans
In Europe/Asia = M.canis
What is the treatment of tinea capitis?
Choix #1 = Terbinafine 2-4 semaines
Alternatif : itraconazole ou fluconazole pour 4 semaines
What is the etiology of favus (severe form of tinea capitis with complete destruction of hair shafts)?
Trichophyton schoenleinii
What emerging dermatophyte causing rapidly spreading annular tinea corporis is resistant to terbinafine?
Trichophyton indotineae - treat with itraconazole
What dermatophyte causes endothrix?
T.tonsurans
T.violaceum
T.soudanese
What dermatophyte causes ectothrix?
M.canis
T.verrucosum
M.audouinii
What is in calcofluor white solution and does it kill fungus?
Calcofluor white + Evan’s blue + Distilled water + most of the time KOH
It only kills fungus if there is KOH in solution!
What is in lactophenol cotton blue solution and does it kill fungus?
Lactic acid + phenol crystals + glycerol + cotton blue
The PHENOL CRYSTALS kill the fungus
What dermatophyte will turn the bromocresol purple media a deep purple color (alkanification)?
Trichophyton mentagrophytes
What dermatophyte will cause a positive hair perforation test?
- T.mentagrophytes
- T.terrestre
What are the species of Aspergillus that can be uniseriate
FFG :
- Fumigatus
- Flavus (is both uni and biseriate)
- Glaucus
All other species of Aspergillus are biseriate
What species of Aspergillus produces cleistothecia (sexual state)?
Glaucus(jaune)
Nidulans(rouge)
Why is Aspergillus calidoustus an important emerging pathogen?
Resistant to triazoles and high MICs to Ampho-B
What species of Aspergillus has intrinsic resistance to ampho-B?
A.terreus
Mutation in what gene will lead to azole resistance in Aspergillus?
14-α-demethylase gene, CYP51A, a component of the ergosterol synthesis pathway and the target of the azole antifungals
What are 2 features permitting differentiation of Rhizopus from Lichtheimia?
- Lichtheimia has a conical apophysis vs Rhizopus has straight apophysis
- Lichtheimia sporangiophores arise in between rhizoids on the stolon vs Rhizopus sporangiophore arise parallel to the rhizoids
- Rhizoïdes bien développés pour Rhizopus
What mold causes brain abscess in near drowning patients?
Scedosporium apiospermium
What are the common agents of Phaeohyphomycosis?
-Exophiala jeanselmei
-Phialophora verrucosa
-Exophiala dermatitidis
-Alternaria
-Cladophialophora bantiana (***Cérébrale)
-Aureobasidium pullulans
-Hormonema
Most common cause of eumycetoma in North America?
- Scedosporium apiospermium species complex (white grains)
Also more common : Madurella spp. (black grains), Trematosphaeria spp. (black grains)
What are the 2 most common causes of chromoblastomycosis?
- Fonsecaea pedrosoi
- Cladophialophora carrionii
Aussi :
- Phialophora verrucosa
- Rhinocladiella aquaspersa
- Exophiala jeanselmei
What is the agent causing Lobo’s disease (Lobomycosis is slow growing keloid like papules)
Lacazia loboi (non-culturable dimorphic fungus - diagnosed on biopsy- can resemble Blasto in pathology stains)
What is the agent of rhinosporidiosis and how is the agent identified?
- Rhinosporidium seeberi - aquatic protistan parasite.
- Haematoxylin and eosin stain on tissues reveal sporangia up to 300microns, can be confused with Prototheca
What is the telemorph (sexual) form of Scedosporium?
Pseudallescheria
What fungus was associated with an outbreak of iatrogenic meningoencephalitis and epidural abscess due to contamination of methyl prednisone?
Exserohilum rostratum
What are the 4 species of “black yeasts”?
- Exophiala
- Hortaea
- Aureobasidium
- Hormonema
What is the classic microscopic appearance Basidiobolus and what part of the body does it affect?
-Club shaped spores and zygospores with beaklike appendage
-Affects limbs, chest, back
What part of the body is affected by conidiobolus?
Nasal mucosa
What yeasts are intrinsically resistant to echinocandins?
- Cryptococcus
- Rhodotorula
- Trichosporon
What are muriform cells and it in what disease are they typically seen?
- Single or clustered fungus cells with dark pigmentation, transverse and longitudinal septa; helps evade host immune system. Also called “sclerotic bodies” or “copper pennies”.
- Key feature of chromoblastomycosis. Cladophialophora spp., Phialophora spp., and Fonsecaea spp. will have that appearance in tissue when there is chromoblastomycosis (will not have their usual morphology with hyphae)
Gélose pour différencier C.neoformans de C.gattii?
CGB agar : canavanine glycine bromothymol blue agar
C. neoformans sera jaune
C. gattii rendra gélose bleue (95% des souches)
Causes de faux positifs de B-D-Glucan? Nommez au moins 4.
Gaze
Produits sanguins, IVIG, albumine
Poussière
Membrane de dialyse avec cellulose
Certaines bactéries (Pseudomonas)
Colonisation à Candida
What Aspergillus specie has a rough conidiophore?
A.flavus
M35 : within what time limit should a germ tube be read for confirmation of C.albicans?
< 3 hours
Other Candida specie can be positive > 3 hours