Question | Answer |
Dimorphic Fungi cause what kind of infections? | Mycoses that involve major body systems or more than one kind of tissue. Don't need "situational" help. |
What is a granuloma? | Collection of macrophages, giant cells, and proteinaceous material that walls off the infection. |
How can yeast forms be disseminated to other organ systems? | Can enter the lymph through macrophages. |
How should these specimens be processed? | Tissue - minced; Pleural fluid and CSF - concentrated; Mucus or pus - mucolytic agent |
When a dimorph is suspected what should be done? | Quick transport; don't hold at room temp; don't refrigerate |
How should dimorphic fungi be set up for culture? | Primary isolation on SDA or SABHI w/ and w/out antimicrobials; incubate at 30C, possibly BHI; PDA for subculture |
What should not be performed on dimorphic fungi in the lab? | Slide cultures |
What type of immune response do they cause? | Cellular |
Where is Blastomyces dermatitidis found? | Endemic in Mississippi river valley; soil saprobe, wood, bark, rotting vegetation, river banks |
What is Blastomycosis? | Chronic granulomatous disease affecting lungs, skin, mucous membranes |
Blastomyces dermatitidis macro | At 25C slow growth mould on SDA, white to beige waxy colony; 37C yeast after 10-15 days on enriched media (BHI) |
Blastomyces dermatitidis micro | Mould = fine, septate, hyaline hyphae; conidia directly on hyphae or on lateral conidiophores; Yeast = hyaline, large cells, Broad Based Budding |
Where is Coccidioides immitis found? | Endemic in SW US and northern Mexico; saprobe in mould form (desert soil); occupational hazard |
What is the most virulent of all agents of human mycoses? | Coccidioides immitis; causes mild infection in all who inhale it |
Coccidioides immitis macro | 3-5 days on SDA/SABHI; arthroconidia in 7-10 days; white and cottony, cobwebs; yeast form not found in lab |
Coccidioides immitis micro | Septate hyaline hyphae; whide arthroconidia that are barrel shaped; disjuncture cells; easily aerosolized - extremely hazardous |
Where is Histoplasma capsulatum found? | Endemic to Mississippi and Ohi river valleys; soil saprobe w/ high nitrogen content; chicken, bird, bat guano; occupational hazard |
What is Histoplasmosis? | Chronic granulomatous lung disease; 5% progress to acute fulminating, rapidly fatal disease = mostly children |
Histoplasma capsulatum macro | Slow growing mould; tan, fluffy; yeast form in 10-15 days on enriched media (BHI or SABHI) |
Histoplasma capsulatum micro | Fine, septate hyphae; micro and macroconidia; macroconidia become tuberculate w/age; yeast cells bud at narrow neck |
Where is Paracoccidioides brasiliensis found? | Endemic to NW, central, and SE South America, Central America, Southern Mexico; Soil saprobe in acid soil |
Paracoccidioides brasiliensis macro | 2-3 weeks mould colony; flat, white colonies; Yeast will form on enriched media at 37C |
Paracocccidioides brasiliensis micro | Fine, septate, hyaline hyphae; conidiation absent on modified SDA; Yeast form - multiple thin necked buds "mariners wheel" |
Where is Sporothrix shenckii found? | Worldwide soil saprobe, occupational risk, gardening "rose gardeners disease" |
What is Sporotrichosis? | Chronic cutaneous and subcutaneous mycosis characterized by ulcers and abcesses along lymphatic channels; not usually in lungs |
Sporothrix shenckii macro | Mould in 3-5 days at 25C; mature colonies are dark and flat; Yeast at 37C, white or tan |
Sporothrix shenckii micro | Mould: delicate, thin hyphae, septate, frequently found at ropes; conidiophores produce multiple conidia in flowerette arrangements; 2 types of conidia: small oval unicellular / large dark walled spheres. Yeast: Cigar shaped at 37C |