Chapter 12: Mycology Flashcards
Properties of Yeasts:
- Nonfilamentous
- Unicellular
- Budding Reproduction
Dimorphic Fungi:
Yeast-like or mold-like depending on conditions.
Fragmentation:
Asexual fungal growth
Formation of Spores:
Sexual and asexual fungal growth
Asexual Spore:
-Formed by hyphae of one organism.
-Spore is genetically identical to parent cell.
-Not enclosed in sac: Conidiophore
Conidiospore (Arthoconidia, blastoconidia, chlamydoconidia).
- Enclosed in sac: Sporangiophore, sporangium, sporangiospore.
Arthroconidia:
Fragmentation of hyphae results in the formation of arthroconidia in coccidiodes immitis.
Blastoconidia:
Formed from the buds of a parent cell of candida albicans.
Chlamydoconidia:
Thick-walled cells within hyphae of this candida albicans.
Candida Albicans:
Pseudohyphae, clamydoconidia, blastoconidia.
Zygomycota:
Rhizopus stolinifer: black bread mold.
asexual spores: sporangiospores
sexual spores: zygospores
Coenocytic
3 Phases of Fungal Sexual Reproduction:
1: Plasmogamy: haploid donor cell nucleus (+) penetrates cytoplasm of recipient cell (-).
2. Karyogamy: + and - nuclei fuse
3. Meiosis: diploid nucleus produces haploid nuclei (sexual spores).
Life Cycle of a Zygomycete:
1) Aerial hypha produce sporangium.
2) Sporangium bursts to release spores.
3) Spore germinates to produce hyphae.
4) Vegetative mycelium grows.
5) Gametes form at tip of hypha.
6) Plasmogamy.
7) Zygospore forms.
8) Karyogamy and meiosis.
9) Zygote produce a sporangium.
10) Spores are released from sporangium.
11) Spore germinates to produce hyphae.
Zygospore:
Fusion of haploid cells produces one zygospore.
Asexual Reproduction:
- Formed by hyphae of one organism.
- Germinated spore genetically identical to parent.
Sexual Reproduction:
- Formed by fusion of nuclei from two opposite strains (+ and -)
- Germinated spore genetic traits of both parents.
- Happens less frequent than asexual reproduction.
Meiosis Key points:
Hypha are haploid
Karyogamy yields diploid cells
Therefore, they must go through meiosis to get back to a haploid state before going through mitosis to make spores.
Anamorphs:
- Produce asexual spores only.
- Most are ascomycota, few basidiomycota.
- Penicillium sporothrix, stachybotrys, coccidioides, pneumocystis, candida albicans.
Basidiomycota:
- Club fungi.
- Septate hyphae.
- Includes mushrooms.
- Produce basidiospores and sometimes conidiospores.
Systemic Mycoses:
Deep within body.
Subcutaneous Mycoses:
Beneath the skin.
Involve dermis, subcutaneous tissue, muscles, fascia, and bone.
-Lesions develop at site of trauma.
-Extends epidermis.
-Difficult to treat, often requires surgical intervention.
Cutaneous Mycoses:
Affect hair, skin, and nails. -Trichophyton: hair, skin, and nails. -Epidermophyton: skin and nails. -Microsporum: hair and skin Signs and Symptoms: -Skin: itchy scaly ring lesions. -Nails: Flaky, patchy, discolored nails. Hair- Balding patches.
Superficial Mycoses:
Localized, hair shafts.
-Limited to outermost layers of skin and hair.
Opportunistic Mycoses:
Caused by normal microbiota or environmental fungi.
-Histoplasmosis:
-Airborne spores.
-Midwest U.S.
-Pathogen: Histoplasma capsulatum.
-Asymptomatic in most cases.
-Symptoms resemble TB.
Coughing with bloody sputum.
-Lesions in most organs.
-Yeastlike form found inside macrophages.
Coccidioidomycosis:
- “Valley fever”
- Fragmentation of hyphae results in formation of arthroconidia.
- SW U.S. and New Mexico.
Pneumocystis Pneumonia:
- Unknown what causes it, possibly human or soil transmission.
Symptoms: Pneumonia.
Treatment: Trimethoprim.
Tinea Versicolor:
Dual pigmented ringworm on various places of the bodys’ skin.
Tinea Manuum:
Ringworm on arms legs etc.
Tinea corporis:
Ringworm on arms usually caused by pets.
Tinea Capatis:
Ringworm on the head.
Tinea Cruris:
Ringworm around gluteus maximus and crotch region.
Tinea Barbae:
Ringworm around beard region of face.
Sporotrichosis:
Gardener’s condition.
- Most common U.S. disease of the subcutaneous mycoses.
- Sporothrix schenchii enters puncture wound.
Opportunistic Fungi:
Aspergillus fumigatus, candida, mucor, rhizopus.
-Predisposing factors weaken immune system making body more susceptible. (Cancer, diabetes, immunocompromised state).
Candidiasis:
- Caused by candida albicans (yeast infection)
-Can be on chest, orally, in eyes, buttocks.
Greater risk with diabetes, obesity, antibiotic use, oral contraceptives, or pregnancy.
How does the morphology of candida albicans contribute to the microbes pathogenicity?
Pseudohyphae
How might the use of penicillin result in a case of candidiasis?
Imbalance of normal flora.
Aspergillosis:
- Rare
- Asthmatic attacks and bronchitis.
- Pulmonary: balls of fungal elements in the lungs.
- Can invade other tissues and organs. Including inner ear, sinuses, and rarely eyes.
Cryptococcosis:
Encapsulated yeast; not dimorphic.
- Inhaled from dust containing dried pigeon droppings.
- Leads to minor pulmonary infections and sometimes meningitis.
Mycotoxins:
Toxin produced by fungi.
- Ergot poisoning: Claviceps purpurea: Saint anthony’s fire, LSD, migraines, hemorrhage/labor delivery.
- Leads to reduced blood in limbs.
Aflatoxin Poisoning:
- Aspergillus flavus.
- Carcinogenic properties.
- Thought to be altered to a mutagenic compound in the human body.
- Leads to live cirrhosis and sometimes liver cancer.
-Mycotoxicosis:
- Poisonous mushrooms called BASIDIOCARPS.
- Responsible for over 90 percent of human deaths from fungus poisoning.
Trichothecenes:
- Inhibit protein synthesis in eukaryotic cells.
- Symptoms: Headaches, chills, nausea, vomiting, visual disturbances.
