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MYCOLOGY AND VIROLOGY > Laboratory Diagnosis, Specimen Collection & Serologic Test > Flashcards

Laboratory Diagnosis, Specimen Collection & Serologic Test Flashcards

1
Q

What is the first step in specimen collection?

A

Aseptic technique

Aseptic technique is crucial to prevent contamination during specimen collection.

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2
Q

What type of specimen is most important if the infection is disseminated?

A

Blood

Blood specimens provide an accurate measure of determining the etiology of disseminated fungal infections.

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3
Q

What is the optimal incubation temperature for blood cultures?

A

30 deg C

Blood cultures should be incubated at 30 degrees Celsius for up to 21 days.

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4
Q

What is a biphasic broth-agar system?

A

Contains both solid and liquid media

This system allows organisms to grow in both solid and liquid environments.

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5
Q

What technique is optimal for isolation of H. capsulatum?

A

Lysis centrifugation technique (Isolator)

This technique lyses cells containing the organism and gathers concentrates for culture.

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6
Q

Which specimens are included under respiratory secretions?

A

Sputum, Bronchoalveolar lavage (BAL), Bronchial washings, Tracheal aspirate

These are common specimens for fungal culture and should use media with antibiotics.

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7
Q

What is the recommended method for collecting cerebrospinal fluid (CSF)?

A

Filtered through a 0.45 um membrane pore filter

This method allows for the collection of organisms present in the CSF.

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8
Q

How should urine specimens be processed?

A

Centrifuge → smear → culture (sediments)

Urine specimens should be processed within 2 hours or refrigerated, but not kept for more than 6 hours.

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9
Q

What is the procedure for collecting hair specimens?

A

Pluck hair by roots (forceps or tweezers)

Care must be taken to avoid damaging infected hair, and Woods lamp can be used for visualization.

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10
Q

What type of culture media should be used for cutaneous specimens?

A

Media with antibiotics

Antibiotics are used to prevent bacterial contamination in fungal cultures.

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11
Q

What are the main components required in culture media for fungi?

A
  • Amino acids or urea (source of Nitrogen)
  • Glucose (source of Carbohydrate)

These components are essential for fungal growth in culture media.

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12
Q

What is the advantage of using agar plates for fungal culture?

A

Better aeration and large surface area for better isolation

Agar plates allow for more oxygen to enter, promoting fungal growth.

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13
Q

What type of agar is used for the primary recovery of dimorphic fungi?

A

Brain-Heart Infusion Agar (BHI Agar)

BHI Agar is suitable for the primary recovery of both saprophytic and dimorphic fungi.

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14
Q

What is the purpose of Potato Dextrose Agar?

A

General purpose basal medium for the cultivation of yeasts & molds

It aids in cultivating various fungi and can help differentiate pathogenic from non-pathogenic strains.

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15
Q

What does Chromagar Candida differentiate?

A

Major clinically significant Candida species

This chromogenic agar allows each Candida species to produce characteristic colonies and pigmentation.

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16
Q

What is the function of the India Ink method?

A

Direct microscopic examination of fungal morphology

This method helps in identifying encapsulated organisms like C. neoformans.

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17
Q

Fill in the blank: Specimen rejection criteria can include _______.

A

Hemolysis, improper transport temperature, incorrect patient identifiers

These criteria ensure the integrity of specimens for accurate diagnosis.

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18
Q

True or False: The culture media must include antimicrobials for sterile specimens.

A

False

Antimicrobials are primarily used for non-sterile specimens to prevent bacterial contamination.

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19
Q

What is the recommended storage condition for CSF specimens?

A

Keep at room temperature or at 37 deg C

Refrigeration may kill fungal elements present in the specimen.

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20
Q

What is the purpose of adding a drop of 10% KOH to a specimen?

A

To clear the background and make fungi prominent

KOH is useful for cutaneous specimens.

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21
Q

What does the negative staining method do?

A

Stains the background while keeping the target element colorless

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22
Q

What type of organisms is the negative staining method perfect for?

A

Encapsulated organisms

Example: capsule of C. neoformans.

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23
Q

What does Calcofluor white stain bind to?

A

Chitin and cellulose in the cell wall of organisms

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24
Q

What color indicates the presence of fungi and parasites when using Calcofluor white?

A

Apple-green/bluish-white

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25
Q

What are the components of Lactophenol Cotton Blue (LPCB)?

A
  • Lactic acid
  • Phenol
  • Cotton blue
26
Q

What is the purpose of the Basic Tease Mount method?

A

To separate the individual growth of the organism

27
Q

What should be used instead of cotton swabs when collecting samples?

A

Dacron/rayon swabs

28
Q

What is the result of using cotton swabs in Calcofluor white staining?

A

Cotton fibers may intensely fluoresce, causing interference

29
Q

What does the Gomori’s/Grocott Methenamine Silver stain indicate?

A

Black cell wall of fungi

30
Q

What does the Periodic Acid Schiff (PAS) stain target?

A

Carbohydrates in fungal cell walls

31
Q

What does the Papanicolau stain demonstrate?

A

Better demonstration of B. dermatitidis than wet mounts

32
Q

At what temperature should dermatophyte cultures be incubated before reporting as negative?

A

Room temperature for 6 weeks

33
Q

What is the risk group for dimorphic fungi?

A

Risk Group 3 (may cause lethal diseases)

34
Q

What is the typical growth rate for yeast?

A

Can grow after 24 hours to 4 days

35
Q

What are the types of fungal growth textures?

A
  • Cottony or wooly
  • Velvety or silky
  • Powdery or granular
  • Moist, creamy, pasty
36
Q

What does the Slide Culture/Microculture method preserve?

A

Fungi in their original living state

37
Q

What is the Germ Tube Test used for?

A

To differentiate Candida albicans from other Candida species

38
Q

What indicates a positive result in the Rapid Urease Test for C. neoformans?

A

Color change from peach to magenta

39
Q

What is the sensitivity and specificity of the Latex Agglutination test for Cryptococcosis?

A

Sensitivity - 90.9%; Specificity - 95%

40
Q

What does a positive precipitation band indicate in serological tests?

A

Presence of antibodies

41
Q

What is the main disadvantage of serological tests?

A

False positives due to cross-reactivity

42
Q

What does the Enzyme Linked Immunosorbent Assay (ELISA) detect?

A

Qualitative or screening assay for various fungal infections

43
Q

What is the purpose of molecular identification in fungal diagnostics?

A

To identify organisms using PCR methods

44
Q

What is a major disadvantage of using culture methods for fungal diagnosis?

A

Time-consuming; mold cultures may take several weeks to grow

45
Q

What does the 1,3 β-D-Glucan Assay (Fungitell) detect?

A

High levels of 1,3 β-D-glucan in various fungal species

46
Q

What is the purpose of the Mannan Ag & Anti-Mannan Ab Assay?

A

It is used for the presumptive diagnosis of Invasive candidiasis

This assay detects the presence of mannan and anti-mannan antibodies.

47
Q

Which metabolites are detected in the diagnosis of Candida?

A

D-Arabinitol and Secreted Aspartyl Proteinase

These are metabolites associated with Candida infections.

48
Q

What cells are involved in the elimination of mannan by immune complexes?

A

Kuppfer cells

Kuppfer cells are specialized macrophages located in the liver.

49
Q

What are the causative agents of Cryptococcosis?

A

C. neoformans and C. gattii

These fungi are responsible for the disease known as cryptococcosis.

50
Q

What type of antibodies does the Aspergillosis test detect?

A

IgE antibodies

This indicates an allergic response to Aspergillus species.

51
Q

What does the E-TEST Agar MIC Method help determine?

A

The Minimum Inhibitory Concentration (MIC) of antifungal agents

This method assists physicians in selecting appropriate antifungal treatments.

52
Q

What is the significance of the clear zone in the E-TEST?

A

It indicates the edge of the ellipse that meets a specific MIC measurement

The clear zone shows the effectiveness of the antifungal agent.

53
Q

Which test is widely used for Candida albicans?

A

Sensititre Yeast One

This is a microbroth dilution MIC test for various Candida species.

54
Q

What types of testing methods are included in the summary for fungal diagnosis?

A
  • Microscopic
  • Culture
  • Serological
  • Molecular
  • Sensitivity tests
  • Aftercare

These methods encompass a range of diagnostic techniques for fungal infections.

55
Q

What is the purpose of the FungiTest?

A

It identifies which concentration of drugs is susceptible

This test uses a microbroth dilution breakpoint method.

56
Q

What does a pink (+) result indicate in the FungiTest?

A

Resistant

A blue (-) result indicates sensitivity.

57
Q

What is the recommended waste management practice for highly infectious waste?

A

Disinfect at source and autoclave culture plates and tubes

If autoclaving is not possible, soaking in a disinfectant is advised.

58
Q

What are the disposal methods for hazardous waste?

A
  • Hazardous waste landfill
  • Safe burial
  • Incineration

These methods ensure safe disposal of infectious waste.

59
Q

Fill in the blank: The culture for Candida krusei shows susceptibility to _______.

A

5Fc (Flucytosine)

Other drugs show varying levels of susceptibility.

60
Q

What is the significance of a drug concentration of S <0.5 ug/mL for Itraconazole?

A

It indicates sensitivity to the drug

This is important for effective treatment strategies.

MYCOLOGY AND VIROLOGY (4 decks)

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