Funky Fungi
Conidiospore definition
produced in a chain, not enclosed in a sac
Arthrospore
specialized conidiospore in which septate hyphae break up into spores resembling barrels
Paracoccidioides brasiliensis
Dimorphic Mickey Mouse or Mariner's Wheel Found in cool damp soil from southern Mexico to South America esp. Brazil - most common mycosis of Latin America Disease onset can take years Forms lesions which may be permanent
Zygomycoses
Disease caused by Mucor, Rhizopus or Absidia species Opportunistic WW, common in soil and as food spoilage agents Diabetics extremely susceptible, and IV drug users and cancer patients
Chlamydospore definition
thick-walled spore formed within a hyphal segment
Where is Coccidioides immitis found?
Dry soil of American Southwest (a.k.a. Valley Fever, San Joaquin Fever)
What do yeasts produce when they grow without oxygen?
Ethanol and carbon dioxide (CO2) - beer and wine production
Candida albicans
Forms chlamydospore - thick-walled spore formed within a hyphal segment
Who is most susceptible to acquiring sporotrichosis?
Gardners, esp. Rose gardeners (Rose pickers disease) - forms small ulcer at site of inoculation, travels up lymph system and causes lesions along pathway, disease takes years to develop, diagnose and cure
Which four fungi are true pathogens?
Histoplasma Coccidioides Blastomyces Paracocciocioides
What are two examples from our class notes of systemic mycoses?
Histoplasmosis and Coccidioidomycosis
How do you diagnose Cryptococcus neoformans?
India ink preparation of cerebral spinal fluid - look for large polysaccharide capsule surrounding yeast cells
What does it mean if the hyphae are coencytic?
It means that it has a continuous appearance
What does it mean if the hyphae have septate?
It means that they show a cross-walled appearance
Subcutaneous Mycosal pathogens
Main cause in U.S. is Sporothrix schenckii - causes sporotrichosis
What is an example of a mycoses that causes piedra?
Malassezia furfur
What are the three main dermatomycoses from our class notes?
Microsporum Epidermophyton Trichophyton
Where is Blastomyces dermatitis usually found?
Mississippi Valley a.k.a. - North American blastomycosis, most infections asymptomatic but there are some fatalities annually
What type of fungi contains hyphae?
Molds the body of molds are composed of long filaments or hyphae
If someone tells you to observe the Mycelium in the mold sample, what are you looking for?
Mycelium is a mass of hyphae that are visible to the unaided eye - the "mold colony"
Candida albicans - Candidiasis
Normal skin flora, mucus membranes (bacteria normal flora keep growth of yeas down) Esp. problematic in diabetics who have elevated sugar in blood and urine Also dangerous for AIDS patients - can be life-threatening Responsible for 10% of hospital-acquired septicemias
Pneumocystis Pneumonia (PCP)
Only causes disease if immunosuppressed 75% of U.S. population has antibodies by age 4 Disease was rarely seen prior to AIDS epidemic Infects lung tissue forming thick walled cysts Part of success in treating HIV is prophylactic treatment for Pneumocystis - usually trimethoprim-sulfamethoxazole (SXT)
What diseases is Malessezia furfur responsible for?
Pityriasis a.k.a. - tinea versicolor dandruff seborrhea fluoresces pale green when exposed to ultraviolet light
Sporangiospore example
Rhizopus
How are subcutaneous mycoses transmitted?
Usually by puncture wound
Where do dermatophytes cause infection?
epidermis, hair or nails
Picture of tinea versicolor
hyperpigmented areas of skin in caucasian Malessezia furfur interferes with melanin production
What are pseudohyphae?
"fake" hyphae that some yeasts produce i.e. Candida albicans
What fungi in this chapter have aerial hyphae?
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Epidermophyton picture
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How do you acquire an infection with a dermatophyte?
...
Microsporum picture
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Pneumocystis Pneumonia
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Which fungal diseases are opportunistic?
1. Blastomyces 2. Cocciodioides 3. Histoplasma 4. Paracocciocioides
What terms are used to describe the asexual reproduction of dimorphic fungi?
1. Conidiospore 2. arthrospore 3. Blastoconidia (aka blastospores) 4. Chlamydospore 5. Sporangiospore
What are the five classifications of mycosis?
1. Systemic 2. Subcutaneous 3. Cutaneous 4. Superficial 5. Opportunistic
What are the three classifications of fungi?
1. Tue yeasts 2. True molds 3. Dimorphic
What four factors determine opportunistic mycosis?
1. medical procedures 2. medical therapies 3. preexisting conditions 4. lifestyle factors
What are a few unique things about dimorphic fungi?
1. most pathogens are found here 2. they frequently have 2 names because scientists did not know they were looking at two versions of the same organism 3. they can reproduce sexually or asexually, however, in the lab they usually see asexual reproduction and this is how they are identified
What is the definition of dimorphic fungi?
A fungi that can grow as a yeast or a mold depending on the temperature they are gown at
What are aerial hyphae?
Aerial hyphae produce spores for sexual or asexual reproduction
How does Histoplasma capsulatum cause Histoplasmosis in humans?
Airborne conidia are inhaled
Where do you find superficial mycoses?
Along hair shaft or on superficial epidermal cells
What is the prevalence of Histoplasmosis in the U.S. population?
Approximately 75% of population in affected areas have antibodies to Histoplasmosis, only 5% develop clinical disease
Arthrospore picture
Arthrospores of Coccidioides immitis
What is the difference between black piedra and white piedra?
Black piedra are hard and white piedra are soft, creamy
What are the four main systemic mycosal pathogens from the class notes?
Blastomyces dermatitidis Coccidioides immitis Histoplasma capsulatum Paracoccidioides
Coccidioides immitis
Body temperature spherule form (grows at room temperature)
Chlamydospore example
Candida albicans
Blastoconidia picture
Candida blastoconidia
Chlamydospore picture
Chlamydospore from C. albicans
Arthrospore example
Coccidioides
What is a Mycosis?
Fungal disease
What diseases is Tricophyton responsible for?
Ringworm, athletes foot, jock itch
What type of fungi is usually responsible for this type of infection?
Saprophytic fungi (a fungi that obtains its food osmotically from decaying organic matter) usually found in soil
How do you diagnosis a dermatomycoses infection?
Scraping of infected skin, hair, or nails and view microscopically in 10% KOH or by culturing
Who is most at risk of developing Histoplasmosis?
Spelunkers, miners, bird breeders, and chicken farmers
Sporangiospore picture
Sporangiospore of Rhizopus
How is Zygomycoses contracted?
Spores are inhaled, may cause lesions on head or neck or inside sinuses or lungs
What is an example of a saprophytic fungi that causes subcutaneous mycosis from the class notes?
Sporothrix
How is sporotrichosis acquired?
Sporothrix schenckii must be "inoculated" into tissue by a cut
What is a fungal infection beneath the skin?
Subcutaneous mycoses
What is a fungal infection that affects a number of tissues or organs?
Systemic mycoses
What appearance do yeast colonies have?
They appear creamy
What do all the main systemic mycosal pathogens have in common?
They are all dimorphic
How do dermatophytes degrade keratin?
They secrete keratinase
Picture of Blastomyces dermatitis grown at 37 degrees Celsius
Thick cell wall budding formation - yeast
What is the treatment for Malessezia furfur?
Topical antifungal ointment
What are the three examples of dermatophytes from the class notes?
Tricophyton Microsporum Epidermophyton
Histoplasmosis picture
Tx: amphotericin B for serious cases, mild cases get Ketoconazole
What is the usual mode of transmission of systemic mycoses?
Usually caused by inhaled spores, usually from soil fungi
How are you infected with Coccidioides immitis?
When the fungus is in soil it produces arthrospores that become airborne, driving through the area and inhaling the spores leads to infection. Most cases are subclinical but you can develop TB-like illness that disseminates
Histoplasma capsulatum grown at 37C
Yeast form
Which fungi is non-filamentous?
Yeasts
Can these dermatophytes be transmitted by direct contact with an infected individual?
Yes, but this type of transmission is not common
What are piedras?
a "stone" or hard nodule along the hair shaft caused by a superficial mycoses infection
How does the disease blastomycosis progress?
begins in the lungs (inhalation of the conidia), can spread rapidly, causing cutaneous ulcers & abscesses. In AIDS patients esp dangerous can cause meningitis
Blastoconidia (aka blastospores)
buds coming off parent cell
Dermatomycoses is...
contagious from person-to-person and from inanimate objects!
Sporangiospore definition
contained within a sac at end of aerial hyphae
Picture of Blastomyces dermatitidis grown at room temperature (cold environment)
lollipop formation (mycelial formation) - mold
Histoplasma capsulatum grown at 25C
mycelial (filamentous) form, macroconidia and microconidia
Conidiospore example
Aspergillus
Conidiospore picture
Aspergillus conidiospore
At what environment will a dimorphic fungi grow as a yeast?
At high temperature - 37 degrees C
At what environment will a dimorphic fungi grow as a mold?
At low temperature - 25 degrees C
Histoplasma capsulatum
Dimorphic Found east of Missippi in US and in specific areas where bat and bird population is numerous Causes Histoplasmosis
What are the opportunistic pathogens from the class notes?
1. Candida albicans 2. Cryptococcus neoformans 3. Pneumocystis jiroveci (previously P. carinii) 4. Zycomycota family (Rhizopus, Mucor, Absidia) 5. Aspergillus
Blastoconidia example
Candida, Cryptococcus
What do yeasts produce when they grow in the presence of oxygen?
Carbon dioxide (CO2) and water (H2O) - bread production
Coccidioides immitis
Conidiospore, dimorphic Form thick-walled bodies full of spores Causes Coccidioidomycosis - most virulent of the fungal pathogens
Cryptococcus neoformans
Contracted by inhaling spores from bird droppings, then begins as asymptomatic lung infection Common clinical presentation: meningitis
What is Dermatomycoses?
Cutaneous pathogen caused by dermatophytes - fungi that can grow in the keratin of hair, nails & skin
What are cutaneous mycoses also known as?
Dermatophytes