Fungi Flashcards
Histoplasma capsulatum
- Mississippi & Ohio River Valley
- Dimorphic (yeast & mold)
- Hot temperature = yeast (body)
- Under microscope, does not have hyphae or branching filaments (that characterize a typical mold)
- Exposure in caves
- Spores from bird/bat droppings
Histoplasmosis
* Presents as pneumonia
* CXR = patchy bilateral infiltrates hilar lymphadenopathy & cavitations (similar to TB)
* Splenomegaly
* Pancytopenia
* Mouth ulcers
Lab findings:
* Granulomatous inflammation (mediastinal lymph nodes)
* Macrophages filled with histoplasma (Oval-shaped fungi)
Rx
* Itraconazole = 1st line drug
* Amphotericin B for severe systemic infection
*
Blastomyces dermatitis
- Great Lakes region
- Michigan, Minnesota, & Ohio
- Dimorphic fungus
- Yeast = warm temperatures
- Biopsy will show yeast form (not mold form)
- Transmitted by inhaled spores
- Cannot be transmitted from person-to-person (must be exposed to the environmental spores)
Blastomycosis
* Pneumonia
* Fever, cough, and SOB
* CXR = nodular infiltrates & reticular nodular patterns, cavitations (can look like TB)
* Verrucous skin lesions
* Osteomyelitis
Dx
* Microscopy = broad-based budding yeast
* Biopsy = granuloma
Rx
* Itraconazole = choice for mild-to-moderate infection
* Fluconazole, Ketoconazole
* Amphotericin B = severe systemic blastomyces infection
Yeast - definition
Unicellular form.
Mold - definition
Multiple cells coming together to form hyphae.
Coccidioides
- Dimorphic fungus
- Large spherule filled with endospheres
- Southwestern USA
- San Joaquin Valley fever
- Transmitted by inhalation of dust spores
- Archaeological digs & earthquakes
Coccidioidal mycosis
* Pneumonia
* CXR = pulmonary infiltrates and swelling around the hilum
* Arthralgias – symmetric distribution involving ankles, feet, and legs
* Erythema nodosum
* Target lesions (Erythema multiforme) – necklace-like distribution
Dx
* Biopsy = granulomas + spherules
* Anti-Coccidoides Ab
Rx
* moderate = supportive care
* severe local symptoms = Itraconazole/Fluconazole
* severe systemic infection = Amphotericin B
“Spherule” appearance inside the body can really lead to the Dx of which fungus?
Coccidioides
Paracoccidioides
Dimorphic fungus
* yeast in the body
* Latin America fever
* Most affected males +++
* Transmitted by inhalation of spores
* Cannot be transmitted person-to-person
Paracoccidioides
* Pneumonia
* Can progress into chronic inflammatory lung disease
* CXR = pulmonary infiltrates and upper respiratory mucosal lesions
* Anemia (90% of all acute cases)
* Mucosal ulcers (oral)
* Skin lesions (verrucous)
Dx
* Biopsy = captain’s wheel appearance (budding daughter cells around a round central yeast cell– larger than a RBC)
* Granulomas
Rx
* Itraconazole = 1st line for mild-to-moderate infection
* Amphotericin B for severe infection
“Mold in the cold. Yeast in the heat.”
Verrucous lesions
Wart-like growths
Malassezia
- Dimorphic fungus
- Transmitted in hot/humid climates
- Tinea/Pityriasis versicolor = macules & patches on the skin (trunk, neck, face, body)
- hypopigmented, hyperpigmented, erythematous patches (3 types)
- Stratum corneum is affected
Biochemistry
* Malassezia inhibits the Tyrosinase enzyme involved in melanin production
Dx
* Preparation of skin scrapings with KOH
* “spaghetti & meatballs appearance” = spores & hyphae filaments in the mold forms
Rx
* Selenium Sulfide (1st line) from shampoos and topical creams
* Itraconazole/Fluconazole = 2nd line fungal agents
Candida albicans
- Opportunistic pathogen
- Single-celled budding yeast with Pseudohyphae
- Forms hyphal germ tubes
- White color colonies
- Immunocompromised are affected: diabetics, elderly, obese, impaired T-cell function
- Associated with antibiotic use
Candida skin test
* to evaluate for cell-mediated hypersensitivity (Type 4)
Presentation
* Oral/esophageal thrush (HIV, asthmatics)
* Vaginitis (Hx of antibiotic use or immunocompromised status)
* Skin folds = candida intertrigo
* Under the diaper in neonates
Dx
* Clinical intuition
* Yeast pseudohyphae on microscopy
* Culture & look for formation of germ tubes
Rx
* Fluconazoles for most infections
* Nystatin for oral/ESO thrush (not abosbed in GI tract & administered in a swish and swallow formulation)
* Echinocandins for **severe disseminated **infections
Aspergillus fumigatus
- Opportunistic pathogen
- Filamentous fungus most often causing lung infections
- Narrow filamentous, septated hyphae branching at acute angles
- Mainly exists in a mold form
- Grows on decaying vegetation
- Immunocompromised patients (HIV, cancer, transplants)
Presentation
Invasive aspergillosis
* invasion of the lung & pneumonia, hemoptysis
* Granulomas seen in the lungs
* Rx = Voriconazole
Aspergillomas
* Non-invasive form of lung disease
* form in pre-existing lung cavities (i.e. from prior TB infection)
* Can be seen in immunocompetent patients
ABPA
* asthma/hypersensitivity-like reaction to the fungus in the lungs
* Wheezing & shortness of breath
* mostly seen in asthma & CF patients
* Lab = eosinophilia, elevated blood IgE/IgA
* Rx = corticosteroids
Aflatoxins
* Potent carcinogens that are a byproduct of corn & soybean metabolism
* when crops are left in humid conditions
* Risk factors = onsuming meat, etc.
* hepatocellular carcinoma (HCC)
Which fungus is seen under microscopy with this description: “narrow filamentous septated hyphae with acute angle branching?”
Aspergillus fumigatus
What is a highly dangerous complication of aflatoxins produced by Aspergillus?
Hepatocellular carcinoma (HCC).
Cryptococcus neoformans
Encapsulated halo yeast that is the most common cause of infections in the CNS (fungal meningitis)
- NOT dimorphic
- India ink stain & mucicarmine – visualize thick polysaccharide capsule
- opportunistic infections
- Bird droppings inhaled into lungs
- Hematogenous dissemination to the meninges
Cryptococcosis
* *Meningoencephalitis *– “soap bubble lesion” on brain MRI
Dx
* CSF w/ wide halos on India ink stain
* Latex agglutination test – detecteds polysaccharide capsular antigen in CSF
Rx
First
* Amphotericin B & flucytosine
Maintenance to prevent recurrence
* fluconazole
Mucor & Rhizopus
Severe sinus infections
- Opportunistic infection
- Mold form only
- Broad, non-septate hyphae (contrast with Aspergillus)
- Wide (right) angle branching
- Transmission by spore inhalation
- Immunocompromised patients – uncontrolled diabetes (DKA)
Mucormycosis
* Necrotic paranasal sinus infection = Black eschar
* Spreads to orbits of the eye and brain
* headaches, vision loss, neuro symptoms
Dx
* Surgical debridement
Rx
* Amphotericin B immediately
Prognosis
* Poor
* Mortality rate of 50%
Pneumocystic jirovecii
Spore-producing fungus
- Opportunistic infection
Presentation
* PCP = pneumocystic pneumonia
* CXR = diffuse bilateral interstitial infiltrates
Dx
* Sputum or bronchoalveolar lavage
Rx
* TMP-SMX – start prophylaxis in HIV/AIDS pts (less than 200 CD4+ count)
* Pentamidine for severe disease
Sporothrix schenckii
Rose Gardener’s Disease
Found in vegetation – think Roses
- Dimorphic fungus
- Yeast in humans & mold in nature
- Hyphae with bouqet-like rosettes in mold
- Cigar-shaped budding yeast, narrow-based budding
Sporotrichosis
* Ulcerating nodule at the ulcer site
* Lymphatic spread with additional ulcerating lesions
* Disseminated disease in immunocompromised
Dx
* Biopsy = granulomas
Rx
1st line
* Itraconazole
2nd line
* KI
* Terbinafine
What are the important biopsy stains for Cryptococcus neoformans?
- India ink - halos
- Mucicarmine - red capsule
TMP-SMX generic name is:
Bactrim
