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M2 | Microbiolgy > General Mycology > Flashcards

General Mycology Flashcards

1
Q

Antibiotics are not effective against _______

A

Fungi

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2
Q

What inhibits peptidoglycan synthesis ?

A

Antibiotics

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3
Q

Mention the features of Fungi :

  • Diameter ——>
  • Nucleus ——->
  • Mitochondria & endoplasmic
    reticulum ——>
  • Cell membrane ——>
  • Cell wall content ——>
  • Spores ——>
  • Thermal dimorphism ——>
  • Metabolism ———>
A

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
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4
Q

Mention the features of Bacteria :

  • Diameter ——>
  • Nucleus ——->
  • Mitochondria & endoplasmic
    reticulum ——>
  • Cell membrane ——>
  • Cell wall content ——>
  • Spores ——>
  • Thermal dimorphism ——>
  • Metabolism ———>
A
  • 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
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5
Q

Mention the structure of yeasts

A

•Single cells
•Reproduce by asexual budding
(daughter cells unequal in size)

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6
Q

Mention the structure of Molds

A

• Hyphae: Long filaments

•Reproduce by cell division
(daughter cells equal in size).

•Mycelium: network of hyphae

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7
Q

What are the “ Dimorphic fungi “ ?

A

fungi exist either as yeasts or molds, depending on temperature

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8
Q

Fill in the blanks :

  1. Room temperature (25°C) in environment yields _______

2. Body temperature (37°C) in human tissues yields _________

A
  1. Molds

2. Yeasts

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9
Q

Describe “Septate hyphae”

A
  • form transverse walls

- branch at acute angles

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10
Q

‘“Aspergillus fumigatus “ is an example of ?

A

Septate hyphae

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11
Q

Most fungi are______ aerobes some are _______

A

Most fungi are “obligate aerobes “

some are “facultative anaerobes”

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12
Q

Define Blastospores

A

budding process by which yeasts reproduce asexually

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13
Q

What is Sporangiospores ?

A

formed within sac (sporangium) on columella by molds

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14
Q

Mention the types of Conidia.

A
  1. Arthrospores
  2. Chlamydospores
  3. Blastospores
  4. Sporangiospores
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15
Q

Most fungi propagate asexually by forming ________

A

Conidia

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16
Q

What are “ Non-septate hyphae” & give an example?

A
  • multinucleated (coenocytic)
  • branch at wide angles
  • e.g. Mucor & Rhizopus
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17
Q

Habitat of most fungi is _______ except _______ is in the normal
human flora

A
  • environment

- Candida albicans

18
Q

Which Conidia is rounded, thick-walled & resistant ?

A

Chlamydospores

19
Q

__________ aids in identification of Candida albicans

A

Terminal chlamydospores

20
Q

Describe the structure of Arthrospores

A

fragmentation of the ends of hyphae

21
Q

Infection of blastomycosis fungi produces ?

a. pyogenic response (neutrophils)
b. macrophages & helper T cells

A

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)

22
Q

Infection with ______ , ______ and ______ causes pyogenic response (neutrophils)

A

Aspergillus, Mucor & Sporothrix

23
Q

Fatty acids in skin inhibit_______

A

dermatophyte growth

24
Q

Limitation of ringworm in the scalp by Trichophyton occurs during ______

A

Hormone-associated skin changes at puberty

25
Q

Intact skin is effective host defense against ________ ,_______

A

Candida , dermatophytes

26
Q

If normal flora is inhibited by antibiotics

_________ happens

A

overgrowth of C. albicans

27
Q

The suppression of Cell-mediated immunity causes what ?

A
  • Reactivation & dissemination of asymptomatic fungal infections
  • Opportunistic fungi diseases
28
Q

What are the mycotoxicoses ?

A

1- Amanita mushrooms

2- Claviceps purpura

3- Aspergillus flavus

29
Q

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 ?

A

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.
30
Q

Which type of mycotoxicose mold causes vasoconstriction ? Explain

A

Claviceps purpura

Because it produces ergot alkaloids that binds to :
1- 5-HT1D serotonin receptors

2- alpha-adrenergic receptors

and this leads to vasoconstriction

31
Q

Which fungi produces lysergic acid diethylamide ?

A

Claviceps purpura

  • lysergic acid diethylamide or ergotamine is another term for ergot alkaloids
32
Q

If you ingested amanita mushroom what will possibly happen to you?

A

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

33
Q

A patient has an asthmatic reaction with rapid bronchoconstriction mediated by IgE & eosinophilia. This hypersensitivity is made by ?

A

Allergy from Aspergillus fumigatus spores

34
Q

What are the risk factors of Aspergillus fumigatus spores ?

A
  • asthma

- cystic fibrosis

35
Q

Mention the laboratory tests that could be done to diagnose presence of fungi

A

1- Direct microscopic examination

2- Culture of organism

3- DNA probes tests

4- Serologic tests

36
Q

Mention the 3 different subtype tests that refers to the blood serum

A

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

37
Q

Elucidate how organisms ( fungi ) are cultured ?

A

Sabouraud’s agar facilitates appearance of slow-growing fungi by ——> inhibiting growth of bacteria in specimen

38
Q

Inhibition of bacteria growth in specimen is due to:

A
  • Low pH of medium

- Penicillin, streptomycin & cycloheximide addition

39
Q

In “ Direct microscopic examination “ which compound is used to help in visualization of fungi ?

A

KOH ——> potassium hydroxide

  • It dissolves human cells that aid in visualizing the fungi
40
Q

A patient suffering from Cryptococcal meningitis is diagnosed by which serological test ? Explain

A

Latex agglutination test :

Indicates polysaccharide capsular antigens of Cryptococcus neoformans in spinal fluid which causes ——> meningitis

41
Q

What does DNA probes tests identify?

A

colonies growing in culture at early stage of growth

42
Q

Blastomycosis can be identified by which test ?

A

Complement fixation

M2 | Microbiolgy (17 decks)

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