dimorphics Flashcards
what kind of hyphae do dimorphic have
septate
why is it called dimorphic?
two forms; yeast and mold
what temp do dimorphics grow best at
30 degrees
infective and dignostic form of dimorphic
infective= mold
diagnostic= yeast seen in tissue
can be invasive
in order to truely ID something as dimorphic need to
get the colony to convert to both forms
-due to pathogenicity don’t often do this in the lab
how are dimorphics diagnosed?
serological by their exoantigens
-several techniques to determine presence of antigen and/or antibody
known as north american blastomycosis or Gilchrist disease
blastomyces dermatitidis
-found in Mississippi river valley region
natural habitat of Blastomyces dermatitidis
warm moist soil so breathe in spores
most affected organ= lungs; but also bones and soft tissues
rare transmission person to person
what can Blastomyces dermatitidis be misdiagnosed as
MRSA because lesions on immunocompromised hosts are filled with pus
yeast form of Blastomyces dermatitidis
appear prickly before typical yeastlike colonies are seen
microscopically have “broad base” neck; thick walled cells
what media does Blastomyces dermatitidis need to grow a good yeast form
cottonseed agar
mold form Blastomyces dermatitidis
slow growing starts white to gray mold
has fuzzy look
septate hyphae
-long conidiospores with single conidia at the top of conidiospores (balloon on a string)
common cause of systemic fungal disease
Histoplasma capsulatum
what disease does Histoplasma capsulatum cause
Spelunker disease
what is spelunkers disease
spores normally inhaled and than travel through the body (bird or bat droppings)
what disease rarely causes a cavitary form of lung disease and may resemble TB on an x-ray
Histoplasma capsulatum
1% of cases become systemic and involves RES
where is the best place to view Histoplasma capsulatum
buffy coat
- will see yeast staining with Giemsa or wright stain
why is history important for Histoplasma capsulatum
if they visited a cave
-infects many organs including gross skin rashes
yeast form of Histoplasma capsulatum
difficult to grow - unless you use media with blood
-yeast can be found in WBCs as crescent shaped
LOOK in buffy coat
Mold form of Histoplasma capsulatum
-macroconidia called tuberculate erechinulate
-no microconidia
conidia are chlamydospores
SPIKEY looks like COVID-19
what disease is called south america blasto
Paracoccidioides brasiliensis
endemic in south america
-most common systemic fungal infection
main way to contract Paracoccidioides brasiliensis
eating contaminated raw leaves/ bark infected with fungus
physical sign you have Paracoccidioides brasiliensis
granulomas along cheek, tongue, jaw, and gum areas
-may cause painful ulcers in oral region
-think gum
victim will swallow spores so result in intestinal disease
yeast form of Paracoccidioides brasiliensis
multiple budding known as “mariners wheel” or “captain’s ship”
-this form easier ID
mold form of Paracoccidioides brasiliensis
sterile hyphae with occasional chlamydospores
where is Coccidiodes immitis/ posadasii
endemic
southwest parts of US in semi-arid, dry areas
spores found in soil and become aerosolized (think dry dust )
in some parts people will test 80% skin + for coccidiodes
what disease is called river valley fever, san joaquin valley fever, or san joaquin river valley fever
Coccidiodes immitis/ posadasii
what does mold produce in Coccidiodes immitis/ posadasii
arthrospores; easily disseminated the older they get so easily airborne
-for this reason must work up coccidiodes with class 3 hood, gown and gloves
-some lab workers get when working with this
how are humans in fected with Coccidiodes immitis/ posadasii
inhale disseminated spores
infections result in mild respiratory type illness; self limiting
also allergic reaction to spores which purpose “red desert bumps”
in some cases pneumonia
in vivo, human lungs do not typically produce yeast cells; instead will see
spherules filled with endospores that will spill out when spherules are broken
endospores will go and infect other tissue
seen in Coccidiodes immitis/ posadasii
mold form Coccidiodes immitis/ posadasii
white cottony mycelium; grow arthrospores
when staining LPCB will see appearance of arthrospores along with “ghost cell” between arthrospores
known as florist’s or gardner’s disease
Sporothrix schenkii
-found in soil and dead vegetation
how is Sporothrix schenkii
transmitted
rose thorns, wood chips, moss
NOT inhaled; transmitted via splinters
what will you see at site of infection of Sporothrix schenkii
purplish, non-healing ulcer that develops about 1-2 weeks after initial contact
organism will travel along lymph nodes forming ulcers
confined to skin
yeast form of Sporothrix schenkii
starts looking like any other yeast, but as gets older will turn black and dematiaceous organism
yeast cells look cigar shaped
mold form of Sporothrix schenckii
thin, delicate septate hyphae
long conidiospores with rosette or bouquet type conidia coming of conidiospores
fairly easy to convert from yeast to mold
most common in INDIA
Talaromyces (penicillium) marneffei
Talaromyces (penicillium) marneffei infection
very disseminating in immunocompromised patients
-isolated from blood, bone marrow
not considered a contaminant like other penicillium
unique features Talaromyces (penicillium) marneffei
dimorphic
does not grow on cycloheximide
prominent red color in mold stage- best with PDA
mold stage Talaromyces (penicillium) marneffei
skeleton hands
-red color
