CULTURE MEDIA Flashcards
What is the primary purpose of Sabouraud’s dextrose agar?
• Primarily used as a general-purpose media.
What microorganisms are typically targeted during the initial isolation process using Sabouraud’s dextrose agar?
• Used for the initial isolation of fungi.
What is the pH range of Sabouraud’s dextrose agar?
• Sabouraud’s dextrose agar typically has a pH range of 5 to 6.
What is the purpose of Dermatophyte Test Medium (DTM) and what indicator does it contain?
• Used to screen for dermatophytes, and it contains phenol red as an indicator.
What is the purpose of adding chloramphenicol and cycloheximide to SDA agar when making Mycosel or Mycobiotic agar?
• To inhibit bacterial and fungal growth other than dermatophytes
• Allowing for the selective recovery of dermatophytes on Mycosel or Mycobiotic agar.
Why is Mycosel or Mycobiotic agar preferred for the recovery of dermatophytes?
• It contains specific additives like chloramphenicol and cycloheximide
• It inhibit unwanted microbial contaminants
What is the purpose of using Cornmeal agar?
• Used to stimulate chlamydospore formation in Candida albicans.
What is the primary purpose of Czapek agar?
• Czapek agar is primarily used for isolating Aspergillus.
What is the purpose of using Niger seed agar or Bird seed agar (Staib’s medium)?
• Used for the cultivation of C. neoformans
Why does C. neoformans develop a brown pigment on Niger seed agar?
• Because of its phenol oxidase activity
• Which leads to the production of this pigment
What is the purpose of using Potato Dextrose Agar in the context of T. rubrum and T. mentagrophytes?
• Demonstrate the production of red pigment with T. rubrum
Why is Potato Dextrose Agar chosen for this demonstration?
• Because it provides a suitable medium for observing the pigment production capabilities of T. rubrum
• Distinguishing it from T. mentagrophytes
How can rice medium be used to differentiate between M. audouinii and M. canis?
• Rice medium is effective for identification because M. audouinii cannot grow on it, while M. canis can.
What is the primary purpose of Urea agar in microbiology?
• Primarily used for differentiating T. mentagrophytes (+) from T. rubrum (-).
What are some other microorganisms that can be identified using Urea agar?
• Used to identify Cryptococcus, Trichosporon, and Rhodotorula species.
Can Urea agar be used for the isolation of C. neoformans?
• Yes, Urea agar can be used to isolate C. neoformans.
What type of medium is Brain Heart Infusion Agar, and what organism is it commonly used to culture?
• Brain Heart Infusion Agar is a type of growth medium
• It is commonly used to culture yeast
What type of medium is Casein medium?
• Casein medium is used for nocardia.
Which agar is utilized for the isolation of Malassezia furfur, causing tinea versicolor?
Malt extract agar
Saprobic and pathogenic
Casein
What is the purpose of using Casein medium?
• Used for the recovery of saprobic and pathogenic fungi.
What can be isolated using Malt extract agar?
• Used to isolate Malassezia furfur, the causative agent of tinea versicolor.
CASEIN
What is the primary purpose of Potato flake agar?
• Potato flake agar is used to recover saprophytes and fungi.
Is Hay infusion agar suitable for fungal culture?
• No, Hay infusion agar is not intended for fungal media.
How should mold cultures be processed according to the note?
• Mold cultures must be processed in a class biosafety cabinet.
What is the purpose of the Hair Perforation or Baiting Test?
• 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.
What is the purpose of the Rapid Urease test?
• To differentiate between T. mentagrophytes(+) and T. rubrum (-).
What does a positive result in the Rapid Urease test indicate?
• The development of a pink to purple color.
Besides dermatophytes, what else can the Rapid Urease test identify?
• It can also be used to identify C. krusei from other candida species.
What is the urease reaction rule for Candida species?
• All candida are urease (-) except for C. krusei.
What is the positive control test organism for the Rapid Urease test?
• C. neoformans.
What is the negative control organism for the Rapid Urease test?
• C. albicans.
What is the purpose of the L-DOPA ferric citrate test in microbiology?
• The L-DOPA ferric citrate test is used for the rapid identification of C. Neoformans
What does a positive result in the L-DOPA ferric citrate test indicate?
• Characterized by the development of a black color
• Suggests the presence of C. neoformans due to its phenol oxidase production
What is the purpose of the Germ Tube Test?
• Used to identify Candida albicans and Candida dubliniensis.
Describe the procedure for the Germ Tube Test.
• 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
What are germ tubes in the context of this test?
• Finger-like extensions or hyphae produced by young yeast cells during the test
How do germ tubes appear in a positive result?
• In a positive result, germ tubes resemble sperm cells under microscopic examination.
What is the Exoantigen test used for?
• Used for serologic confirmation of systemic fungi.
How does the Exoantigen test confirm the presence of fungi causing systemic mycosis?
• It confirms the presence of fungi causing systemic mycosis by detecting specific antigens.
Which antigen is associated with Cocciodes immitis in the Exoantigen test?
• Cocciodes immitis is associated with CF, TP, or HL antigens in the Exoantigen test.
What antigens are associated with Histoplasma capsulatum and Blastomyces dermatitidis in the Exoantigen test?
• Histoplasma capsulatum - with H or M band antigens
• Blastomyces dermatitidis - A band antigen
Why would temperature studies be conducted to differentiate between C. albicans and C. dubliniensis?
• These two species exhibit different growth patterns at varying temperatures
• Allowing for their distinction based on their thermal preferences.
At what temperature can C. albicans grow, and what about C. dubliniensis and C. neoformans?
• C. albicans can grow at 42°C
• Whereas C. dubliniensis and C. neoformans cannot grow at this temperature.
What is the primary purpose of the Carbohydrates Assimilation Test?
• To identify the particular carbohydrate that the fungi can use as a sole carbon source.
Why might one perform this test on a yeast isolate?
• This test is performed on a yeast isolate to identify whether it is free from carbohydrate utilization.
What does the Carbohydrates Assimilation Test indicate about yeast capability?
• To utilize carbohydrate as a sole source of carbon.
What is the purpose of incubating the agar with the yeast suspension at 30°C for 24 hours?
• The incubation is done to observe the growth of yeast around the disc and determine its capabilities.
What does it indicate if the growth around the disc is impregnated with glucose?
• It indicates that the yeast species is capable of using glucose as its sole carbon source.
What does the growth of yeast around the disk indicate?
• The growth of yeast around the disk indicates a positive response to the experimental conditions
What is the significance of detecting anti-fungal antibodies in serology?
• Detecting anti-fungal antibodies in serology helps diagnose sub-cutaneous
• Systemic mycoses, assess prognosis
• Monitor the response to anti-fungal drugs
What are some serologic techniques used for anti-fungal antibody detection?
• agglutination
• immunodiffusion
• counter-immunoelectrophoretic
• complement fixation tests
• immunofluorescence, among others
Name some fungal pathogens for which serology is commonly employed.
• Used for fungal pathogens like Blastomyces, Histoplasma, Cryptococcus, and Aspergillus.
”CABH”
What is the primary purpose of antigen detection in diagnosing cryptococcal meningitis?
• Useful in diagnosing cryptococcal meningitis from CSF specimens.
What methods are commonly used for performing antigen detection tests?
• Typically performed using latex agglutination or immunodiffusion tests.
Besides cryptococcal antigens, what other infections can antigen detection help identify?
• Antigen detection is also helpful in detecting aspergillus and Candida antigens in systemic infections.
What can a positive skin test for fungal antigens indicate?
• Indicates sensitization to fungal antigens, but not necessarily an active infection.
In which fungal infections can skin tests be performed?
• performed in diseases like:
1. Histoplasmosis
2. Candidiasis
3. Sporotrichosis
4. Coccidioidomycosis
5. Blastomycosis
6. Paracoccidioidomycosis
7. dermatophytosis
PHDSCC
What type of reactions can be demonstrated by a skin test using fungal antigens?
• Skin tests using fungal antigens can demonstrate delayed hypersensitivity reactions.
How do newer molecular techniques such as DNA hybridization and PCR benefit the diagnosis of mycoses?
• Enable faster diagnosis of mycoses and help detect fungi that are challenging or unsafe to cultivate in vitro.
Which fungal infections may be detected through serologic tests?
• 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.
What is the purpose of incubating a nitrogen-based agar with a yeast suspension at 30°C for 24 hours and observing growth?
• 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.
Enumerate the 5 fungi that associated with systemic mycosis
- Histoplasma capsulatum
- Blastomyces dermatitidis
- Coccidioides immitis
- Paracoccidioides braziliense
- Penicillium marneffei
Enumerate the 4 OPPORTUNISTIC MYCOSES
- Candida albicans
2.Cryptococcus neoformans - Aspergillus
- Zygomycota
Enumerate the 5 OTHER OPPORTUNISTIC MYCOSES
- Penicilium
- Acremonium
- Pneumocystis Jiro ecii or carinni
4.Geotrichium - Fusarium
