General concepts in Lab diagnosis

Question 1

Surface area: Petri dish

Answer 1

Large (7,500mm2)

Question 2

Surface area: Test tube

Answer 2

Small (1,500mm2)

Question 3

Oxygen supply: Petri Dish

Answer 3

Good

Question 4

Oxygen supply: Test tube

Answer 4

Poor

Question 5

Rate of drying: Petri Dish

Answer 5

Relatively fast

Question 6

Rate of drying: Test tube

Answer 6

Relatively slow

Question 7

Security of closure: Petri Dish

Answer 7

Poor (lid is easily displaced)

Question 8

Security of closure: Test tube

Answer 8

Good

Question 9

Probability of dissemination: Petri Dish

Answer 9

Relatively large

Question 10

Probability of dissemination: Test tube

Answer 10

Relatively small

Question 11

Detection of mixed culture: Petri Dish

Answer 11

Relatively easy

Question 12

Detection of mixed culture: Test tube

Answer 12

Relatively difficult

Question 13

Incubation of Mold forms

Answer 13

25oC to 30oC

Question 14

Incubation of Opportunistic and dimorphic organisms

Answer 14

30oC

Question 15

Incubation of Conversion to yeast phase for dimorphic fungi

Answer 15

25oC to 37oC

Question 16

Rapid growers

Answer 16

< 5 days
Saprobes, opportunistic fungi, yeast

Question 17

Intermediate growers

Answer 17

6 - 10 days
Subcutaneous & opportunistic fungi, dermatophytes

Question 18

Slow growers

Answer 18

> 11 days
Systemic & subcutaneous fungi

Question 19

Appears leather-like, or waxy little mycelium, seems to merge with the agar

Answer 19

Glabrous

Question 20

Resembles plush or suede, short aerial hyphae of equal length

Answer 20

Velvety

Question 21

Resembles colonies of other Staphylococcus spp. (formerly CoNS), “bacteria like” but more dry and dull (waxy-pasty). No aerial mycelium, with a delicate fringe around the colonies in BAP

Answer 21

Yeast like

Question 22

Wooly or “Floccose”, large quantities of long aerial hyphae that becomes entangled and may fill the entire petri dish

Answer 22

Cottony

Question 23

Powdery due to heavy conidiation or sporulation, has even hyphae and abundant conidia

Answer 23

Granular

Question 24

Presence of radial groves from the center of the culture toward the rim

Answer 24

Rugose

Question 25

Random folds (long, short, parallel at right angles or combination)

Answer 25

Folded

Question 26

Have central depression (concavity) surrounded by raised edges. Resembles S. pneumoniae colonies

Answer 26

Crateriform

Question 27

Have many warts or rough knobs on the surface

Answer 27

Verrucose

Question 28

Brain-like convolutions

Answer 28

Cerebriform

Question 29

Four methods of Microscopic evaluation of growth in culture

Answer 29

Tease mount Scotch tape method Slide culture Dalmau method

Question 30

Recommended for studying yeast morphology. It is performed by using one-fourth or one-third of a cornmeal-Tween 80 agar plate for each organism.

Answer 30

Dalmau Method

Question 31

FOur ways of Preservation of cultures

Answer 31

storage in water freezing mineral oil overlay lyophilization

Question 32

Conidia and spores form a fresh culture are washed off in sterile water and placed in labelled vials

Answer 32

Storage in water

Question 33

Labelling glass tubes with a screw-capped and placed in a freezer

Answer 33

Freezing

Question 34

Layering an entire slant with mineral oil, capping the tube tightly and storing at room temperature

Answer 34

Mineral oil overlays

Question 35

Freeze drying with the use of special equipment

Answer 35

Lyophilization

Question 36

temperature in freezing preservation of culture

Answer 36

-70C

Question 37

Aspergillus spp. immunologic assay

Answer 37

CIE, FEIA, EIA

Question 38

Antibod(ies) Antigen(s) detected in Aspergillus spp.

Answer 38

Aspergillus IgG

Question 39

helpful in diagnosing allergic bronchopulmonary aspergillosis (ABPA), aspergilloma, and Chronic cavitary aspergillosis

Answer 39

Aspergillus IgG

Question 40

Blastomyces spp. assay

Answer 40

Commercial kits

Question 41

Blastomyces spp. antibodies or antigens detected

Answer 41

Antigens (eg., A Ag, WI1 Ag)

Question 42

limitation of Blastomyces spp. immunologic detection

Answer 42

lack of sensitivity due to cross- reactivity with dimorphic fungi

Question 43

Candida spp. immunologic assay

Answer 43

EIA

Question 44

Candida spp. Antibod(ies) Antigen(s) detected

Answer 44

Mannan Ag Candida IgG, IgM, & IgA

Question 45

Cryptococcus spp. assay

Answer 45

EIA

Question 46

Cryptococcus spp. Antibod(ies) Antigen(s) detected

Answer 46

Cryptococcus IgG, IgM, IgA Ag: Glucuronoxylmannan

Question 47

can be a marker for reactivation of disease in solid organ transplant recipient

Answer 47

Cryptococcus antibodies

Question 48

A polysaccharide present in the cell wall of many fungi viz., Aspergillus, Candida, Fusarium

Answer 48

1,3-β-D-glucan

Question 49

Found in the blood of patients with invasive fungal infections, and its ability to activate factor G of the horse-shoe crab coagulation pathways that allows it to be measured and quantified.

Answer 49

1,3-β-D-glucan

Question 50

1,3-β-D-glucan detection is rarely or not present in

Answer 50

Cryptococcus, Blastomyces, Mucoraceous molds.

Question 51

Has the ability to detect organisms that are present in small numbers of that cannot be cultured.

Answer 51

Nucleic acid testing

Question 52

Nucleic acid testing removes the risks associated wit culturing especially for

Answer 52

H. capsulatum

Question 53

Offers the potential to identify pathogens in biopsy samples that have been formalin-fixed and even wax-embedded.

Answer 53

Nucleic acid testing