Chapter 12: Fungi Flashcards
Mycosis
Fungal infection (caused by yeast or mold)
Opportunistic mycoses
caused by normal flora such as yeast or mol that are normally present in environment
Candida albicans
-opportunistic mycoses
-Present in vaginal area
-Most common yeast in clinical setting
-Reservoir: normal flora of skin and mucous membranes
-Pseudohyphae present (helps yeast invade tissues)
-Oral Candidiasis (thrush)
-5% in babies
-Transmission: childbirth or breastfeeding
-Can also occur in cancer pt’s
-Candida Esophagitis
-Yeast from oral cavity to esophagus
-Signs and symptoms: trouble breathing, difficulty swallowing
-Vulvovaginitis
-Signs and symptoms: itchy, creamy, pasty vaginal discharge
-Dx:
-Gram stain, wet mount
-Blood agar
-Colonies include whiskers
-Germ tube production
-Sheep or calf serum w/ 1-2 colonies- 2 hrs at 37 degrees celsius> germ tube
-Diabetics and asthmatics susceptible
-Broad spectrum antibiotics
-Transmission opportunistic route or sexual
-Vaginitis
-UTI
-Transmission: opportunistic pathogen; sexual contact
-Dx: gram stain, fungal culture, germ tube production
-Topical treatment w/ miconazole or nystatin; oral ketoconazole
-Act to injure plasma membrane
-onychomycosis- nail infection
-signs and symptoms: cracked, discolored, thickened, and brittle nails, and potentially separation from the nail bed
-prevention: proper hygiene
-treatment: oral or topical anti fungal
Aspergillus
-opportunistic mycoses
-Inhale mold spores
-pulmonary aspergillosis
Superficial mycoses
fungal infections that affect the outermost layers of the skin, hair, and nails.
Cutaneous mycoses
involve the epidermis, hair, and nails, often triggering inflammation and immune responses.
Superficial and cutaneous
Subcutaneous mycoses
Beneath skin
-Sporotrix schenckii
-Dermatomycoses: tinaes or ringworm
-Dermatophytes metabolize keratin
-Reservoir: humans, animals, fomites
-Transmission: direct contact, indirect contact (fomites- inert objects)
-Dx: microscopic exam (KOH prep- spores and hyphae) or fungal culture
-Treatment: Oral griseofulvin, topical miconazole
-3 genera molds:
-Trichphyton
-Epidermophyton
-Microsporum
Systemic mycoses
-Deep tissue fungal infections via bloodstream
-Treatment: Itraconazole or Amphotericin B
-Pneumonia
-Histoplasmosis capsulatum
-Dimorphic
-Coccidioides immitis
-Aspergillus fumigatus
-Environmental mold
-Can present as pulmonary aspergillosis
Defining characteristics of fungi
-Unicellular (fungi) or multicellular (mold) eukaryotes
-Ergosterol in ther plasma membranes
-Chitin in their cell walls
-Reproduce by sexual and asexual spores
-Aerobic or Facultative Anaerobes chemoheterotrophs
-Susceptible to antifungals
Sexual and asexual spores
-Corida (asexual) spore
-Arthrospores (sexual)- retangular
Dx of mycoses
-Microscopic exam: wet preps, KOH (quick prep- potassium hydroxide)
-Gram stain
-Lactophenol cotton
-10x, 40x
-Scotch tape prep
-BSL-3
Dx of mycoses: colonymorphology
-Macroscopic examL colony morphology
-Fungal culture Sabouraud Dextrose Agar
-acidic pH
-Creamy, pasty, white color
-Mold: 25 degrees celsius
-Yeast: 25-37 degrees celsius
Dx of mycoses: serology tests
-Limited biochemical tests for yeast
-Serological tests for antibody or antigen
-Molecular methods
Pathogenesis of fungi: dimorphism
-Dimorphism- 2 phases of growth that are temp. Dependent
-Truly pathogenic
Yeast
-Gram-(+) budding oval-shape
-Some yeast have capsules
-Unicellular, non filamentous fungi
-Reproduce by budding (asexual)
-Produce pseudohyphae
-Especially Candida albicans
-Ferment carbs
Cryptococcus neoformans
-Inhalation of dried pigeon droppings
-Found in urban areas
-Reservoir: soil, Bird dropping (environment)
1Encapsulated- virulence factor
-Cryptococcal Meningitis
-“Cryptococcosis”
-Dx: blood, spinal fluid > wet prep
-Clear halo- capsule
-Gram stain/ India INk of CSF, capsule antigen test, culture (25-30 degrees celsius)
-Treatment: Amphotericin B and flucytosine
-Immunocompromised (reduced T cells) pt’s are most susceptible
-Spinal fluid combined w/ latex beads test (agglutination test- rapid)
-Pneumonia-like symptoms (does not actually cause pneumonia)> then meningitis
-Travel through bloodstream
Pneumocystitis jirovecci (carinii)
-Reservoirs: human lungs, soil
-Transmission: opportunistic routes
-Causes pneumonia in immunocompromised pt’s; AIDS-defining illness
-Life cycle of P. jirovecii
-RNA analysis shows that it closely yeast
1) matures cyst (non reproducing stage) contains 8 intracystic bodies
2) cyst rupture, releasing the bodies
3) bodies develop into trophozoites
4) The trophozoites divide
5) Each trophozoite develops into a mature cyst
-Pneumocystis pneumonia
-Dx: chest x-ray
-Signs and symptoms: difficulty breathing, fever, abnormal chest x-ray
-Dx: giemsa stain for cysts and trophozoites in lung tissue; PCR test
-Mortality in immunocompromised pt’s
-Treatment: Trimethoprim-sulfamethoxazole (SXT)
Molds
-Multicellular filamentous fungi, including fleshy fungi (mushrooms)
-Produce hyphae, a filamentous structure
-Texture, color, growth rate of colonies observed
Septate vs. Nonseptate hyphae
-Septate hyphae: have walls between the cells (septa)
-Nonseptate hyphae: do not have walls or cell membranes between the cells
Vegetative hypae
-Below agar surface
-absorb nutrients
Aerial hyphae
above the agar surface and contain reproductive spores
Mycelium
group of mass of hyphae intertwined
Dermophytes
-Coin sized lesion, itching, scaling
-Dermocated (darker edge)
-Dx: 10% KOH- able to see spores and hyphae and fungal culture
-Ringworm or tinaes
Ringworm transmission
Contact w/ pets (cats and dogs) or person w/ ringworm, or public shower
Dermatomycoses
-Tinae capitis- scalp
-Hair loss
-Barber’s itch (ringworm of beard)
-Tinae corpus- entire body
-Wrestlers
-Tinae pedis (athlete’s foot)
Sporothrix schenkcii
-“Rose gardener’s disease”/Sporotrichosis
-Subcutaneous mycoses
-Often associated w/ one’s occupation- florist, farmer
-Found in soil and plants (thorns of roses)
-Introduced by puncture from thorn> ulcer forms
-Virulence: low, unless pt is immunocompromised- could enter lymphatic system (lymphocutaneous lesions)
-Dimorphic: 2 phases that are temp dependent
-Mold phase
-Yeast phase: 37 degrees Celsius- cigar-shaped cells
-small ulcer on arm of skin
-Source: rose thorns, plants, soil, moss, cat bite
-Transmission: spore traumatically introduced
-Dx: KOH prep (reveal presence of hyphae or spores), fungal culture (SDA plate at 25 degrees celsius)
-Bx of ulcer
-Treatment: Potassium iodide, Itraconazole
-Prevention: gloves and other protection while gardening
Histoplasma capsulatum
-causes histoplasmosis
-Common in Ohio and Mississippi River valleys
-Spores associated w/ bird or bat droppings (increase nitrogen in soil)
-transmission: Inhalation of spores in mold phase (soil)
-Dimorphic
-Yeast in body (37 degrees Celsius) and multiply in phagocytes
-Mold in environment
-Pt may develop mild pneumonitis (coughing up blood)
-Immunocompromised pt’s more susceptible
-Can spread to even brain or bone marrow
-Dx: signs and history: DNA probes, serology, fungal culture
-Treatment: Itraconazole
-Prevention: clearing dust in areas of soil where common, and spraying soil w/ formaldehyde
-signs and symptoms: fever, cough, chest pain, shortness of breath, fatigue, chills, headache, and muscle aches
Coccidioides immits
-Systemic mycoses
-Dimorphic
-Common in San Joaquin Valley
-Reservoir: soil
-Arthroconidia- barrel shaped spore- which is inhaled
-BSL 3
-Signs and symptoms: coughing up blood, fever, chest pain
-Could develop meningitis if pt is immunocompromised
-Coccidiomycosis
-Dx: spherules in tissue, serology, DNA probe , fungal culture
-Treatment: Itraconazole
-Prevention: spray soil w/ formaldehyde; reduce dust
Aspergillus fumigatus
-Reservoir: soil, environment
-Transmission: inhalation of spores
-Tissue section: Branching septate hyphae
-Pulmonary aspergillosis
-Bloody sputum, coughing, fever, chest pain
-Dx: sputum sample, chest x-ray (look for growth of hyphae on lungs- fungus ball (mycelium)- bx)
-Aspergillus hyphae in nasal septum
-Sinusitis
-Aspergillosis in brain tissue
-See want brain scan
-Transmission: inhalation of spores
-Dx: chest x-ray, fungal culture
-Treatment: Itraconazole, Amphotericin B, surgery
Mucor
-opportunitic fungi
-Reservoir: soil, environment
-Transmission: inhalation of spores
-Grows at room temp (25-30 degrees celsius) on SDA
-Nonseptate hyphae
-Mucormycosis
-Infections start in nasal cavity- discharge from nasal cavity
-Gram stain
-Can advance to eye or brain
-Rhinocerebral Mucormycosis
-Invasion of the eye/brain w/in days
-especially in immunocompromised pt’s and those w/ uncontrolled diabetes (could enter brain)
-Dx:
-Collect discharge from nose or eye
-Gram stain (+)
-KOH prep
-Fungal culture on SDA
-Treatment: Itraconazole, Amphotericin B, surgery
-Transmission: inhalation of Spores
-Black discharge
-Could invade sinuses and enter orbits of eyes
-Culture: cotton candy mold
Rhizopus
-Very common in environment
-Transmission: inhalation
-Infection can disseminate throughout the body in immunocompromised pts
-Pulmonary infections
-opportunistic fungi
-causes mucormycosis
-sinus pain, nasal congestion, fever, and in severe cases, black lesions or vision problems.
-can cause infection in: Lungs, Sinuses, Brain, Skin, and Gastrointestinal tract.
-treatment: Itraconazole
-long hypae
-sporangiospore- asexual spore
-systemic mycoses
-noseptate hyphae
Mycotoxins
-Ergot poisoning
-Aflatoxin poisoning
-Fungal toxin causes GI diseases; liver damage
How are fungi beneficial to mankind?
-Antibiotics like penicillin
-Decomposer: breaks down waste
-Yeast: fermentation
List characteristics of fungi
-eukaryotes
-reproduce sexually and asexually
-true fungi contain chitin (carb) in cell walls
-nutrition source: absorption of organic material from their environment
-yeast- unicellular fungi
-larger than bacteria
-oval-shaped
-mold- multicellular fungi
-composed of long filaments of cells (hyphae) that branch and intertwine to form visible masses (mycelia)
Define and describe fungi
Yeast are single-celled fungi that reproduce asexually through budding and are known for their ability to ferment sugars, producing alcohol and carbon dioxide
-candida albicans
Describe and define molds
are microscopic fungi that grow in the form of multicellular filaments called hyphae, requiring moisture, oxygen, and an organic source to thrive
Fleshy fungi
Fleshy fungi, like mushrooms and puffballs, are macroscopic, multicellular fungi characterized by a body (thallus) composed of a network of thread-like filaments called hyphae, which form a tangled mass called a mycelium.
Compare and contrast fungi and bacterial cells.
Fungi:
-multicellular (mold) and unicellular (yeast)
-eukaryotic
-cell wall chitin
-asexual and sexual reproduction
-no motile
Bacteria:
-unicellular
-prokaryotic
-cell wall: peptidoglycan
-asexual reproduction
-motile
