General Mycology Flashcards
Antibiotics are not effective against _______
Fungi
What inhibits peptidoglycan synthesis ?
Antibiotics
Mention the features of Fungi :
- Diameter ——>
- Nucleus ——->
- Mitochondria & endoplasmic
reticulum ——> - Cell membrane ——>
- Cell wall content ——>
- Spores ——>
- Thermal dimorphism ——>
- Metabolism ———>
Fungi :
- Diameter ——> Approximately 4 µm
- Nucleus ——-> Eukaryotic
- Mitochondria & endoplasmic
reticulum ——> Present - Cell membrane ——> Sterols present
- Cell wall content ——> Chitin
- Spores ——> Sexual & asexual spores for reproduction
- Thermal dimorphism ——> Yes (some)
- Metabolism ———> Require organic carbon
———> No obligate anaerobes
Mention the features of Bacteria :
- Diameter ——>
- Nucleus ——->
- Mitochondria & endoplasmic
reticulum ——> - Cell membrane ——>
- Cell wall content ——>
- Spores ——>
- Thermal dimorphism ——>
- Metabolism ———>
- Diameter ——> Approximately 1 µm
- Nucleus ——-> Prokaryotic
- Mitochondria & endoplasmic
reticulum ——> Absent - Cell membrane ——> Sterols absent
- (except Mycoplasma)
- Cell wall content ——> Peptidoglycan
- Spores ——> Endospores for survival, not for reproduction
- Thermal dimorphism ——> No
- Metabolism ———> Many do not require organic carbon
———> Many obligate anaerobes
Mention the structure of yeasts
•Single cells
•Reproduce by asexual budding
(daughter cells unequal in size)
Mention the structure of Molds
• Hyphae: Long filaments
•Reproduce by cell division
(daughter cells equal in size).
•Mycelium: network of hyphae
What are the “ Dimorphic fungi “ ?
fungi exist either as yeasts or molds, depending on temperature
Fill in the blanks :
- Room temperature (25°C) in environment yields _______
2. Body temperature (37°C) in human tissues yields _________
- Molds
2. Yeasts
Describe “Septate hyphae”
- form transverse walls
- branch at acute angles
‘“Aspergillus fumigatus “ is an example of ?
Septate hyphae
Most fungi are______ aerobes some are _______
Most fungi are “obligate aerobes “
some are “facultative anaerobes”
Define Blastospores
budding process by which yeasts reproduce asexually
What is Sporangiospores ?
formed within sac (sporangium) on columella by molds
Mention the types of Conidia.
- Arthrospores
- Chlamydospores
- Blastospores
- Sporangiospores
Most fungi propagate asexually by forming ________
Conidia
What are “ Non-septate hyphae” & give an example?
- multinucleated (coenocytic)
- branch at wide angles
- e.g. Mucor & Rhizopus
Habitat of most fungi is _______ except _______ is in the normal
human flora
- environment
- Candida albicans
Which Conidia is rounded, thick-walled & resistant ?
Chlamydospores
__________ aids in identification of Candida albicans
Terminal chlamydospores
Describe the structure of Arthrospores
fragmentation of the ends of hyphae
Infection of blastomycosis fungi produces ?
a. pyogenic response (neutrophils)
b. macrophages & helper T cells
Answer: b. macrophages & helper T cells
Why? ——> Infection with systemic fungi such as in Histoplasma, Coccidioides and blastomycosis causes ——> granulomatous host defense response (macrophages & helper T cells)
Infection with ______ , ______ and ______ causes pyogenic response (neutrophils)
Aspergillus, Mucor & Sporothrix
Fatty acids in skin inhibit_______
dermatophyte growth
Limitation of ringworm in the scalp by Trichophyton occurs during ______
Hormone-associated skin changes at puberty
Intact skin is effective host defense against ________ ,_______
Candida , dermatophytes
If normal flora is inhibited by antibiotics
_________ happens
overgrowth of C. albicans
The suppression of Cell-mediated immunity causes what ?
- Reactivation & dissemination of asymptomatic fungal infections
- Opportunistic fungi diseases
What are the mycotoxicoses ?
1- Amanita mushrooms
2- Claviceps purpura
3- Aspergillus flavus
Genetic analysis of a liver biopsy specimen shows a G:C to T:A transversion in codon 249 of the gene coding for the TP53 protein is affected . What is the risk factor most specific to the patient’s condition? Explain why ?
Answer: Dietary aflatoxin exposure
Explanation:
- aspergillus flavus produces Aflatoxins which causes hepatic carcinoma
- Aflatoxins are ingested with spoiled grains & peanuts
- They are metabolized by liver to epoxide (potent carcinogen)
- Aflatoxin B1 interferes with DNA transcription of tumor suppressor gene 53 (TP53) mutation in TP53 gene base transversions leads to ——> loss of p53 protein & loss of growth control in hepatocyte.
Which type of mycotoxicose mold causes vasoconstriction ? Explain
Claviceps purpura
Because it produces ergot alkaloids that binds to :
1- 5-HT1D serotonin receptors
2- alpha-adrenergic receptors
and this leads to vasoconstriction
Which fungi produces lysergic acid diethylamide ?
Claviceps purpura
- lysergic acid diethylamide or ergotamine is another term for ergot alkaloids
If you ingested amanita mushroom what will possibly happen to you?
Ingestion of Amanita mushrooms includes amanitin & phalloidin amanitin toxins
which they in return —> inhibit RNA polymerase thus it prevents mRNA synthesis ( protein synthesis) ——>This will induce liver necrosis
A patient has an asthmatic reaction with rapid bronchoconstriction mediated by IgE & eosinophilia. This hypersensitivity is made by ?
Allergy from Aspergillus fumigatus spores
What are the risk factors of Aspergillus fumigatus spores ?
- asthma
- cystic fibrosis
Mention the laboratory tests that could be done to diagnose presence of fungi
1- Direct microscopic examination
2- Culture of organism
3- DNA probes tests
4- Serologic tests
Mention the 3 different subtype tests that refers to the blood serum
Blood serum ——> Serologic tests
1- Significant rise in antibody titer :
- in patient’s serum or spinal fluid in systemic mycoses
2- Complement fixation : coccidioidomycosis, histoplasmosis & blastomycosis
3- Latex agglutination test :
- polysaccharide capsular of Cryptococcus neoformans in spinal fluid
Elucidate how organisms ( fungi ) are cultured ?
Sabouraud’s agar facilitates appearance of slow-growing fungi by ——> inhibiting growth of bacteria in specimen
Inhibition of bacteria growth in specimen is due to:
- Low pH of medium
- Penicillin, streptomycin & cycloheximide addition
In “ Direct microscopic examination “ which compound is used to help in visualization of fungi ?
KOH ——> potassium hydroxide
- It dissolves human cells that aid in visualizing the fungi
A patient suffering from Cryptococcal meningitis is diagnosed by which serological test ? Explain
Latex agglutination test :
Indicates polysaccharide capsular antigens of Cryptococcus neoformans in spinal fluid which causes ——> meningitis
What does DNA probes tests identify?
colonies growing in culture at early stage of growth
Blastomycosis can be identified by which test ?
Complement fixation
