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DIAGNOSTIC MYCOLOGY > CULTURE MEDIA > Flashcards

CULTURE MEDIA Flashcards

1
Q

What is the primary purpose of Sabouraud’s dextrose agar?

A

• Primarily used as a general-purpose media.

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2
Q

What microorganisms are typically targeted during the initial isolation process using Sabouraud’s dextrose agar?

A

• Used for the initial isolation of fungi.

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3
Q

What is the pH range of Sabouraud’s dextrose agar?

A

• Sabouraud’s dextrose agar typically has a pH range of 5 to 6.

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4
Q

What is the purpose of Dermatophyte Test Medium (DTM) and what indicator does it contain?

A

• Used to screen for dermatophytes, and it contains phenol red as an indicator.

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5
Q

What is the purpose of adding chloramphenicol and cycloheximide to SDA agar when making Mycosel or Mycobiotic agar?

A

• To inhibit bacterial and fungal growth other than dermatophytes
• Allowing for the selective recovery of dermatophytes on Mycosel or Mycobiotic agar.

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6
Q

Why is Mycosel or Mycobiotic agar preferred for the recovery of dermatophytes?

A

• It contains specific additives like chloramphenicol and cycloheximide
• It inhibit unwanted microbial contaminants

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7
Q

What is the purpose of using Cornmeal agar?

A

• Used to stimulate chlamydospore formation in Candida albicans.

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8
Q

What is the primary purpose of Czapek agar?

A

• Czapek agar is primarily used for isolating Aspergillus.

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9
Q

What is the purpose of using Niger seed agar or Bird seed agar (Staib’s medium)?

A

• Used for the cultivation of C. neoformans

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10
Q

Why does C. neoformans develop a brown pigment on Niger seed agar?

A

• Because of its phenol oxidase activity
• Which leads to the production of this pigment

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11
Q

What is the purpose of using Potato Dextrose Agar in the context of T. rubrum and T. mentagrophytes?

A

• Demonstrate the production of red pigment with T. rubrum

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12
Q

Why is Potato Dextrose Agar chosen for this demonstration?

A

• Because it provides a suitable medium for observing the pigment production capabilities of T. rubrum
• Distinguishing it from T. mentagrophytes

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13
Q

How can rice medium be used to differentiate between M. audouinii and M. canis?

A

• Rice medium is effective for identification because M. audouinii cannot grow on it, while M. canis can.

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14
Q

What is the primary purpose of Urea agar in microbiology?

A

• Primarily used for differentiating T. mentagrophytes (+) from T. rubrum (-).

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15
Q

What are some other microorganisms that can be identified using Urea agar?

A

• Used to identify Cryptococcus, Trichosporon, and Rhodotorula species.

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16
Q

Can Urea agar be used for the isolation of C. neoformans?

A

• Yes, Urea agar can be used to isolate C. neoformans.

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17
Q

What type of medium is Brain Heart Infusion Agar, and what organism is it commonly used to culture?

A

• Brain Heart Infusion Agar is a type of growth medium
• It is commonly used to culture yeast

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18
Q

What type of medium is Casein medium?

A

• Casein medium is used for nocardia.

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19
Q

Which agar is utilized for the isolation of Malassezia furfur, causing tinea versicolor?
Malt extract agar
Saprobic and pathogenic

A

Casein

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20
Q

What is the purpose of using Casein medium?

A

• Used for the recovery of saprobic and pathogenic fungi.

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21
Q

What can be isolated using Malt extract agar?

A

• Used to isolate Malassezia furfur, the causative agent of tinea versicolor.

CASEIN

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22
Q

What is the primary purpose of Potato flake agar?

A

• Potato flake agar is used to recover saprophytes and fungi.

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23
Q

Is Hay infusion agar suitable for fungal culture?

A

• No, Hay infusion agar is not intended for fungal media.

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24
Q

How should mold cultures be processed according to the note?

A

• Mold cultures must be processed in a class biosafety cabinet.

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25
Q

What is the purpose of the Hair Perforation or Baiting Test?

A

• To differentiate T. mentagrophytes (+) from T. rubrum (-)
• Based on the presence of V-shaped or conical hair perforations that are not visible to the naked eye.

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26
Q

What is the purpose of the Rapid Urease test?

A

• To differentiate between T. mentagrophytes(+) and T. rubrum (-).

27
Q

What does a positive result in the Rapid Urease test indicate?

A

• The development of a pink to purple color.

28
Q

Besides dermatophytes, what else can the Rapid Urease test identify?

A

• It can also be used to identify C. krusei from other candida species.

29
Q

What is the urease reaction rule for Candida species?

A

• All candida are urease (-) except for C. krusei.

30
Q

What is the positive control test organism for the Rapid Urease test?

A

• C. neoformans.

31
Q

What is the negative control organism for the Rapid Urease test?

A

• C. albicans.

32
Q

What is the purpose of the L-DOPA ferric citrate test in microbiology?

A

• The L-DOPA ferric citrate test is used for the rapid identification of C. Neoformans

33
Q

What does a positive result in the L-DOPA ferric citrate test indicate?

A

• Characterized by the development of a black color
• Suggests the presence of C. neoformans due to its phenol oxidase production

34
Q

What is the purpose of the Germ Tube Test?

A

• Used to identify Candida albicans and Candida dubliniensis.

35
Q

Describe the procedure for the Germ Tube Test.

A

• To perform the Germ Tube Test
• Transfer colonies to serum
• Incubate at 37°C for 3 hours
• Examine a drop under a microscope for germ tube formation

36
Q

What are germ tubes in the context of this test?

A

• Finger-like extensions or hyphae produced by young yeast cells during the test

37
Q

How do germ tubes appear in a positive result?

A

• In a positive result, germ tubes resemble sperm cells under microscopic examination.

38
Q

What is the Exoantigen test used for?

A

• Used for serologic confirmation of systemic fungi.

39
Q

How does the Exoantigen test confirm the presence of fungi causing systemic mycosis?

A

• It confirms the presence of fungi causing systemic mycosis by detecting specific antigens.

40
Q

Which antigen is associated with Cocciodes immitis in the Exoantigen test?

A

• Cocciodes immitis is associated with CF, TP, or HL antigens in the Exoantigen test.

41
Q

What antigens are associated with Histoplasma capsulatum and Blastomyces dermatitidis in the Exoantigen test?

A

• Histoplasma capsulatum - with H or M band antigens
• Blastomyces dermatitidis - A band antigen

42
Q

Why would temperature studies be conducted to differentiate between C. albicans and C. dubliniensis?

A

• These two species exhibit different growth patterns at varying temperatures
• Allowing for their distinction based on their thermal preferences.

43
Q

At what temperature can C. albicans grow, and what about C. dubliniensis and C. neoformans?

A

• C. albicans can grow at 42°C
• Whereas C. dubliniensis and C. neoformans cannot grow at this temperature.

44
Q

What is the primary purpose of the Carbohydrates Assimilation Test?

A

• To identify the particular carbohydrate that the fungi can use as a sole carbon source.

45
Q

Why might one perform this test on a yeast isolate?

A

• This test is performed on a yeast isolate to identify whether it is free from carbohydrate utilization.

46
Q

What does the Carbohydrates Assimilation Test indicate about yeast capability?

A

• To utilize carbohydrate as a sole source of carbon.

47
Q

What is the purpose of incubating the agar with the yeast suspension at 30°C for 24 hours?

A

• The incubation is done to observe the growth of yeast around the disc and determine its capabilities.

48
Q

What does it indicate if the growth around the disc is impregnated with glucose?

A

• It indicates that the yeast species is capable of using glucose as its sole carbon source.

49
Q

What does the growth of yeast around the disk indicate?

A

• The growth of yeast around the disk indicates a positive response to the experimental conditions

50
Q

What is the significance of detecting anti-fungal antibodies in serology?

A

• Detecting anti-fungal antibodies in serology helps diagnose sub-cutaneous
• Systemic mycoses, assess prognosis
• Monitor the response to anti-fungal drugs

51
Q

What are some serologic techniques used for anti-fungal antibody detection?

A

• agglutination
• immunodiffusion
• counter-immunoelectrophoretic
• complement fixation tests
• immunofluorescence, among others

52
Q

Name some fungal pathogens for which serology is commonly employed.

A

• Used for fungal pathogens like Blastomyces, Histoplasma, Cryptococcus, and Aspergillus.
”CABH”

53
Q

What is the primary purpose of antigen detection in diagnosing cryptococcal meningitis?

A

• Useful in diagnosing cryptococcal meningitis from CSF specimens.

54
Q

What methods are commonly used for performing antigen detection tests?

A

• Typically performed using latex agglutination or immunodiffusion tests.

55
Q

Besides cryptococcal antigens, what other infections can antigen detection help identify?

A

• Antigen detection is also helpful in detecting aspergillus and Candida antigens in systemic infections.

56
Q

What can a positive skin test for fungal antigens indicate?

A

• Indicates sensitization to fungal antigens, but not necessarily an active infection.

57
Q

In which fungal infections can skin tests be performed?

A

• performed in diseases like:
1. Histoplasmosis
2. Candidiasis
3. Sporotrichosis
4. Coccidioidomycosis
5. Blastomycosis
6. Paracoccidioidomycosis
7. dermatophytosis

PHDSCC

58
Q

What type of reactions can be demonstrated by a skin test using fungal antigens?

A

• Skin tests using fungal antigens can demonstrate delayed hypersensitivity reactions.

59
Q

How do newer molecular techniques such as DNA hybridization and PCR benefit the diagnosis of mycoses?

A

• Enable faster diagnosis of mycoses and help detect fungi that are challenging or unsafe to cultivate in vitro.

60
Q

Which fungal infections may be detected through serologic tests?

A

• Blastomyces, histoplasma, Cryptococcus, and aspergillus
• Can be detected through serologic tests
• However, it’s important to note that serologic test kits and molecular techniques may not be available for all fungi.

61
Q

What is the purpose of incubating a nitrogen-based agar with a yeast suspension at 30°C for 24 hours and observing growth?

A

• to assess the ability of yeast to utilize the impregnated carbohydrate in the agar as a carbon source
• which is indicated by observing their growth over the incubation period.

62
Q

Enumerate the 5 fungi that associated with systemic mycosis

A
  1. Histoplasma capsulatum
  2. Blastomyces dermatitidis
  3. Coccidioides immitis
  4. Paracoccidioides braziliense
  5. Penicillium marneffei
63
Q

Enumerate the 4 OPPORTUNISTIC MYCOSES

A
  1. Candida albicans
    2.Cryptococcus neoformans
  2. Aspergillus
  3. Zygomycota
64
Q

Enumerate the 5 OTHER OPPORTUNISTIC MYCOSES

A
  1. Penicilium
  2. Acremonium
  3. Pneumocystis Jiro ecii or carinni
    4.Geotrichium
  4. Fusarium

DIAGNOSTIC MYCOLOGY (23 decks)

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