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?

-

Epidermophyton picture

...

How do you acquire an infection with a dermatophyte?

...

Microsporum picture

...

Pneumocystis Pneumonia

...

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