Mycology Flashcards
What is a dermatophyte?
Fungus with the ability to obtain nutrients from keratin and therefore infects skin, hair, or nails.
What is hyaline vs dematiaceous?
Hyaline is see through, dematiaceous is pigmented.
Is it a yeast, mold, or dimorphic: Candida
Yeast
Is it a yeast, mold, or dimorphic: Cryptococcus
Yeast
Is it a yeast, mold, or dimorphic: Geotrichum
Yeast
Is it a yeast, mold, or dimorphic: Saccharomyces
Yeast
Is it a yeast, mold, or dimorphic: Rhodotorula
Yeast
Is it a yeast, mold, or dimorphic: Trichosporon
Yeast
Is it a yeast, mold, or dimorphic: Malassezia
Yeast
Is it a yeast, mold, or dimorphic: Histoplasma
Dimorphic
Is it a yeast, mold, or dimorphic: Blastomyces
Dimorphic
Is it a yeast, mold, or dimorphic: Coccidioides
Dimorphic
Is it a yeast, mold, or dimorphic: Paracoccidioides
Dimorphic
Is it a yeast, mold, or dimorphic: Talaromyces marneffei
Dimorphic
Is it a yeast, mold, or dimorphic: Sporothrix Schenckii
Dimorphic
Is it a yeast, mold, or dimorphic: Rhizopus
Mold
Is it a yeast, mold, or dimorphic: Rhizomucor
Mold
Is it a yeast, mold, or dimorphic: Mucor
Mold
Is it a yeast, mold, or dimorphic: Alternaria
Mold
Is it a yeast, mold, or dimorphic: Bipolaris
Mold
Is it a yeast, mold, or dimorphic: Curvularia
Mold
Is it a yeast, mold, or dimorphic: Exserohilum
Mold
Is it a yeast, mold, or dimorphic: Fonsecaea
Mold
Is it a yeast, mold, or dimorphic: Scedosporium
Mold
Is it a yeast, mold, or dimorphic: Microsporum
Mold
Is it a yeast, mold, or dimorphic: Trichophyton
Mold
Is it a yeast, mold, or dimorphic: Epidermophyotn
Mold
Is it a yeast, mold, or dimorphic: Aspergillus
Mold
Is it a yeast, mold, or dimorphic: Fusarium
Mold
Is it a yeast, mold, or dimorphic: Acremonium
Mold
Is it a yeast, mold, or dimorphic: Scopulariopsis
Mold
Is it a yeast, mold, or dimorphic: Penicillum
Mold
How are molds sub divided?
Zygomycetes, dematiaceous, dermatophytes, hyaline hyphomycetes
What are zygomycetes?
This is a phylum of fungi that have broad irregularly 90 degree/right angle branched hyphae with rare septations.
Name the hyaline hypomycetes [5]
Aspergillus, fusarium, acremonium, scopulariopsis, pencillium
Name the dermatophyes [3]
Microsporum, trichophyton, Epidermophyton
Name the dematiaceous molds [6]
Alternaria, Bipolaris, Curvularia, Exserohilum, Fonsecaea, Scedosporium
Name the Zygomyctes [3]
Rhizopus, Rhizomucor, Mucor
Name the thermally dimorphic molds [6]
Histoplasma, Blastomyces, Coccidioides, Paracoccidioises, Talaromyces marneffei, Sporothix
Name the Non-Candida yeasts [6]
Cryptococcus, geotrichum, saccharomyces, rhodotorula, trichosporon, malassezia
Name the 6 types of candida
Albicans, brusei, parapsilosis, glabrata, tropicalis, lusitanie
What is the most common and 2nd most common cause of BSI with yeast?
Candida is the most common, Cryptococcus is the second most common.
How is candida differentiated from Cryptococcus microscopically?
Candida forms pseudohyphae and is oval shaped. Cryptococcus is larger, round, has a visible capsule and NEVER forms pseudohyphae
What does malassezia require to grow?
Oil or tween
C. albicans resistance pattern
Susceptible to fluconazole and echinocandins.
C. tropicalis resistance pattern
Susceptible to fluconazole and echinocandins.
C. Dubliniensis resistance pattern
Susceptible to fluconazole and echinocandins.
C. guilliermondii resistance pattern
Susceptible to fluconazole and echinocandins.
C. glabrata resistance pattern
Resistant to fluconazole. Susceptible to echinocandins but resistance is rising. 2nd most common candida infection
C. parapsilosis resistance pattern
Susceptible to fluconazole, increased MIC to echinocandins
C. parapsilosis causes what sort of disease?
Central line and implantable device diseases due to biofilm formation.
C. krusei resistance pattern
Resistant to fluzonazole, susceptible to echinocandins. May be resistant to amphotericin B and flucytosine
What types of patients get C. krusei infection?
Those with hematologic malignancy 2/2 azole prophylaxsis
C. lusitaniae resistance pattern
Resistant to amphotericin B but susceptible to fluzonazole and echinocandins.
C. auris resistance pattern
Resistant to fluconazole, ampho B, echinocandins
What is C. auris often mislabeled as?
Saccharomyces or C. haemulonii
Can candida cause pneumonia?
It is very uncommon and needs a biopsy for confirmation.
Micro shows yeast with pseudohyphae with clusters of blastoconidia at the septa. Diagnosis?
Candida
What infections does cryptococcus cause?
Meningitis, pneumonia, skin infections, sepsis
Micro shows round budding yeast with no hyphae. Diagnosis.
Cryptococcus
Who is at risk for cryptococcus infections?
HIV with CD4 <100, transplant recipients, those on steroids, those with malignancy and liver disease
What infections doe Geotrichum cause?
BSI, pneumonia
Micro shows arthroconidia that are in chains. Rectangle or barrel shaped. True hyphae are seen. Diagnosis?
Geotrichum
Risk factors for Geotrichum?
Neutropenia, heart valve surgery in immunocompromised host.
What infections does rhodotorula cause?
BSI, and CLABSI.
Micro shows unicellular blastoconidia, globose to elongated in shape. No hypae or pseudohypae. Growth is orange, red, or coral colored. Diagnosis?
Rhodotorula
What is rhodotorula associated with?
Central lines in immunocompromised
How does saccharomyces cause infection?
Associated with probiotic use. BSI. Rare infection.
Micro shows unicellular globuse and ellipsoid to elongated blastoconida with multipolar budding. Diagnosis?
Saccharomyces.
Micro shows round to oval nonbudding with comma-shaped focal thickening on the wall. Diagnosis?
Pneumocystis jirovecii
Micro shows small oval budding yeast at 37 degrees celsius and septate hyphae with round/pear shaped microconidia and large tuberculate macroconidia at 25-30 degrees celsius. Diagnosis?
Histoplasmosis.
Micro shows broad-based budding yeast at 37 degrees celsius and septate branched hyphae with intercalary or terminal chlamydospores at 25-30 degrees celsius. Diagnosis?
Blastomycosis
Micro shows round thic-walled spherules containing endospores at 37 degrees celsius and septate branched hyphae with thick-walled arthroconidia at 25-30 degrees celsius. Diagnosis?
Coccidioides
Micro shows large round thick-walled yeast with ship’s-wheel appearance budding at 37 degrees celsius and septate branched hyphae with intercalary or terminal chlamydospores at 25-30 degrees celsius. Diagnosis?
Paracoccidioides
Where is paracoccidioides endemic?
South America
What type of infection does talaromyces marneffei cause?
Skin, CNS, bone infections
Micro shows small oval non-budding yeast at 37 degrees celsius with smooth conidiophores with 4-5 terminal metulae. each metulae bearing 4-6 phialides at 25-30 degrees celsius.
talaromyces marneffei
Where is talaromyces marneffei endemic?
Southwest and Southern China and Southeast Asia
What fungus has a biopsy that resembles squamous cell cancer?
Blastomyces
What causes rose handler’s disease?
Sporothrix
Micro shows small fusiform budding yeast at 37 degrees celsius and narrow septate hyphae with tapering conidiophores at right angles at 25-30 degrees. Diagnosis?
Sporothrix
Micro shows thick-walled budding yeast at 37 degrees ant septate hyphae with round conidiophores at right angle at 25-30 degrees. Diagnosis?
Emonsia
What disease does emmonsia cause?
Pneumonia and skin infection
Who gets emmonsia?
Those with CD4 <100, this with malignancy, transplant patients. Those in South Africa
Micro shows branched sporangiophores with no rhizoid structure. Diagnosis?
Mucor
Micro shows nonbranching sporeangiophore originatinf from hyphae with rhizoid structure directly below the sporangiophore. Diagnosis?
Rhizopus
Micro shows brnaching sporangiophore with rhizoid structure away from the origin of sporangiophore. Diagnosis?
Rhizomucor
Who are at high risk for mucor? [5]
Uncontrolled DM, hematoligic malignancy, transplant, iron over-loard, or those on iron chelation.
What is the treatment for mucor?
Ampho B for severe infections. Psoaconazole or isavuconazole for step-down after induction or for mild/moderate infection.
Do dimorphic fungi ever represent contaminates?
No.
Do hyaline hyphomycetes ever represent contaminants?
Yes! Get lab confirmation.
Micro shows septate hyphae with conidiophore ending in phialides radiating around vesicle. Diagnosis?
Aspergillus
Micro shows septate hyphae with canoe-shaped macroconidia. Diagnosis?
Fusarium
Which fungus is able to sporulate inside the body and disseminate through the blood and yield positive blood cultures?
Fusarium
How does fusarium present?
Seen during engraftment phase post stem cell transplant with skin lesions and fevers. Often starts with cellulitis surrounding toenails.
Fusarium treatment?
Ampho B and vorizonazole prior to species level identification.
Aspergillus treatment?
Voriconazole.
General treatment methods for hyphomycete infections?
Ampho B for severe, voriconazole/isavuconazole for mild/moderate.
In general what is treatment for dematiaceous molds
Surgical debridement, ampho B or voriconazole
How are dematiaceous molds differentiared in tissue from hyaline hyphomyctes?
Fontana-Mason stain [stains the melanin in dematiaceous molds]
What fungi might grow in a patient on amphotericin? [8]
C. lusitaniae, C. auris, fusarium, aspergillus terreus, Scedosporium apiospermum, Lomentospora prolificans, Sporothrix schenckii, Pseudallesdheria boydii
Utility of blood culture with yeasts?
Most yeast grow well in blood cultures.
Utility of blood culture with dimorphic fungi?
Can be positive in severe disseminated disease but this is a slow and insensitive method.
Micro shows dark septate hyphae with alternating septated conidia. Diagnosis?
Alternaria
Who gets alternaria?
Those with hematologic malignancy HSCT, and neutropenia.
Micro shows dark septate hyphae with elongated septate conidia that taper at both poles. Diagnosis?
Bipolaris [tapers at both poles…bipolar]
Who gets bipolaris infection
Those with hematologic malignancy, HSCT, neutropenia.
Micro shows dark sepatate hyphae, septate curved conidia. Diagnosis?
Curvularia
Who gets culvularia?
Those with hematologic malignancy, HSCT, neutropenia.
Micro shows septate hyphae with swollen elongated conidia. Diagnosis?
Scedosporium/Lomentospora
Who gets Scedosporium/Lomentospora?
Immunocompromised patients.
Micro shows dark budding yeast like cells that eventually produce spetate hyphae and flask-shaped conidiogenous cells. Diagnosis?
Exserohilum
What fungus is associated with outbreaks during natural disasters?
Exserohilum
What fungus was associated with contaminated steroid injections?
Exserohilum
What type of agar do most fungi grow on?
Emmons modification of sabourauds dextrose agar or potato dextrose agar
What temp should fungi be incubated at?
25 degrees celsius to assist in identification of dimorphic molds
How long will it take for fungal cultures to become positive?
4 weeks for many, 3 days for candida.
What is a lactophenol cotton blue stain?
Identifies fungal structures from colonies on cultures [NOT tissue stains]. Lactic acid is a clearing agent and preserves fungal structures. Cotton blue stains.
What is a calcofluor white stain?
Binds to cellulose and chitin and fluoresces when exposed to long wave UV light.
How is pneumocystis usually idenitifed?
Direct fluorescent antibody stain.
What is a giemsa stain used for?
Typically to detect intracellular organisms such as malaria, chlamydia. Also detects yersinia. In mycology it detects intracellular histoplasma in bone marrow or blood smears
How does a gomori methamine silver stain work?
Mucopolysaccharide components of the fungal cell wall react with silver nitrate reducing it to metalic silver rendering a brown-black compound. Fungi look black on a green back round.
How does a periodic acid-schiff stain work in fungi?
Periodic acid attacks carbohydrates containing 1,2-glycol or OH group with conversion to 1,2-aldehydes which then react with the fuchsin-sulfurous acid to form a magenta color.
Utility of PAS stain?
Pan stain similar to GMS
What is a mucicarmine stain used for?
Histologic visualization of mucopolysaccharides in the capsule of cryptococcus neoformans/gattii. Differentiates cryptococcus from other yeasts in tissues. Can also stain Rhinosporidium and Blastomyces dermatitiddis
How does a fontana-masson silver stain work?
Oxidizes melanin and melanin-like pigments as it reduces silver giving a visible black color.
What is a fontana-masson stain used for?
Differentiates fungi that produce melanin and dematiaceous molds from those who do not. It will also be positive with capsule-deficient [and therefore mucicarmine negative] cryptococci.
What is T2Candida assay?
Uses Magnetic resonance to detect candida. It is 91% sensitive and 99% specific.
What candida can T2 detect? [5]
Albicans, tropicalis, parapsilosis, krusei, glabrata.
What is 1,3 beta-D-Glucan?
Cell wall component of many fungi. Typically used as a candida marker.
What will make beta-d-glucan positive?
IVIG, IV penicillin, pneumocysitis, histoplasma
What fungi is beta-d-glucan NEGATIVE?
cryptococcosis, zygomycetes
What is galactomannan?
It is a polysaccharide constituent of Apergillus cell walls?
What can make galactomannan false positive?
Fusarium, penicillium, histoplasma, zosyn, augmentin used to be positive if made before 2010. [May be positive up to 5 days after stoping abx.]
What can make galactomannan false negative?
Antifungal use.
What can make cryptococcal antigen false positive?
Rarely Trichosporon asahii, Rothia, Capnocytophaga.
What is the utility of the quantitative histoplasmosis assay?
Helps ascertain severity of the infection and monitors for antigen clearance.
On what is histoplasmosis antigen performed?
Blood, urine [most common], CSF
What are the sensitivities of histoplasmosis antigen?
90% positive in BAL, 75% in CSF
What can lead to a false positive histoplasmosis antigen?
Blastomycosis [so high that often the histoplasmosis urine antigen is used to diagnosis blastomycosis], talaromycosis, paracoccidioidomycosis, coccidioidomycosis
What can cause false negative histoplasmosis antigen?
Localized disease [only pulm], immunosuppression
What can cause false negative histoplasmosis antigen?
Localized disease [only pulm], immunosuppression
How do histoplasma antibodies work?
Uses immunodiffusion to report M or H precipitin bands. M band becomes positive soon after exposure and is positive in most patients. H band is seen in <20% of cases but is specific for disseminated infection, chronic cavitary pulmonary histo, or severe acute pulmonary histo.
Does H band clear? M band?
Yes, 6 months after infection. M band persists for years.
What does the presence of M band alone indicate?
Early or chronic disease.
What titer is sensitive for acute infection with M and H bands?
1:32 or higher.
What can cause a false positive histoplasmosis antibody?
Coccidioidomycosis, blastomycosis, some granulomatous disease such as sarcoid and TB.
What can cause false negative histoplasmosis antibody?
Immunosuppression.
What can cause cross reactivity with blastomyces antibodies?
Histoplasma capsulatum exposure. NOT A GOOD TEST AND IS RARELY USED.
How long does it take for coccidoides IgM and IgG to show up in the serum? How long does it take for it to go back down?
IgM: 1 week; persists 2-3 months
IgG: 3-6 weeks; persists 2 years
What coccidio complement fixation antibody titer is suggestive of dissemination?
> 1:16
What is the utility of CF antibody titer for coccidio?
It has prognostic, diagnostic, and response to therapy.
What is the utility of CSF coccidio antibodies?
It is highly specific for meningitis
What is the utility of a coccidio antigen?
Useful in immunocompromised moreso in the setting of negative serologies and can serve as a surogate marker of fungal burden in severe disease and be used to monitor response to therapy.