Specimen Collection and Processing

Question 1

the most common procedure performed in the area of parasitology is the examination of a stool specimen for _

Answer 1

ova and parasites (abbreviated as O&P)

Question 2

ova refers to the _ stage of parasite

Answer 2

egg

Question 3

When present, the protozoan forms known as _ may be recovered from these samples.

Answer 3

trophozoites and cysts

Question 4

_ stages, such as eggs, larvae, proglottids, and adult worms, may also be found.

Answer 4

Helminth

Question 5

The typical stool collection protocol con- sists of three specimens, one specimen collected every other day or a total of _ collected in _.

Answer 5

3; 10 days

Question 6

Stool samples from patients whose therapy includes _ oil should be col- lected prior to therapy or not until 5 to 7 days after the completion of therapy.

Answer 6

barium, bismuth, or mineral

Question 7

Collection of speci- mens from patients who have taken antibiotics or antimalarial medications should be delayed for _ following therapy.

Answer 7

2 weeks

Question 8

Amount of stool required for parasite study

Answer 8

2-5 g; “walnut size”

Question 9

t/f. Urine should not be allowed to con- taminate the stool specimen because it has been known to destroy some parasites.

Answer 9

true

Question 10

Stool should not be retrieved from toilet bowl water because _ may be con- fused with human parasites.

Answer 10

free-living protozoa and nematodes

Question 11

To demonstrate the motil- ity of protozoan trophozoites, a _ specimen is required.

Answer 11

fresh

Question 12

liquid stool must be examined within _

Answer 12

30 minutes

Question 13

usually found in liquid stool

Answer 13

trophozoites

Question 14

semiformed specimen should be evaluated within

Answer 14

1 hour

Question 15

usually seen in semiformed specimen

Answer 15

protozoan cysts and trophozoites

Question 16

formed specimens can be held for _

Answer 16

24 hours

Question 17

substances that preserve the morphology of protozoa and prevent further development of certain helminth eggs and larvae

Answer 17

fixatives

Question 18

recommended part of fixative and stool

Answer 18

3:1

Question 19

The specimen must be fixed in the preservative for at least _ minutes before processing begins.

Answer 19

30

Question 20

all-purpose fixative for the recovery of protozoa and helminths

Answer 20

formalin

Question 21

5% formalin concentration ideally preserves

Answer 21

protozoan cysts

Question 22

10% formalin concentration ideally preserves

Answer 22

helminth eggs and larvae

Question 23

does not preserve parasite morphology adequately for permanent smears (-)

Answer 23

formalin

Question 24

a plastic powder that acts as an adhesive for the stool specimen when preparing slides for staining

Answer 24

polyvinyl alcohol

Question 25

PVA combined with Schaudinn solution has _ chloride base which can cause potential health problem.

Answer 25

mercuric

Question 26

viable alternative to the use of PVA and Schaudinn fixative

Answer 26

SAF (sodium acetate formalin)

Question 27

requires a single vial and it is mercury-free

Answer 27

SAF

Question 28

SAF is easy to prepare, has a long shelf life, and can be used for preparing smears for staining with the modified acid-fast stain to detect _

Answer 28

coccidian oocysts

Question 29

t/f SAF-preserved specimens is not as clear in permanent stains as when mercury-containing preservatives are used.

Answer 29

true

Question 30

SAF for permanent stains with _ provide better results

Answer 30

iron hematoxylin

Question 31

Other alternatives to mercury-based PVA are the use of sub- stitute compounds containing copper sulfate or zinc sulfate

Answer 31

modified polyvinyl alcohol

Question 32

free of formalin and mercury and can be used for concentration techniques and permanent stained smears

Answer 32

alternative single-vial systems

Question 33

Conspicuously fibrous

Answer 33

hard (dark brown)

Question 34

Fiber scanty to moderate

Answer 34

soft (black)

Question 35

colloidal (homogenous)

Answer 35

mushy (brown)

Question 36

scanty mucus

Answer 36

loose (pale brown)

Question 37

much mucus

Answer 37

diarrheic (clay)

Question 38

mucus with scanty blood

Answer 38

watery, liquid (yellow)

Question 39

formed stool color

Answer 39

red-brown

Question 40

semiformed stool color

Answer 40

green, other

Question 41

The microscopic examination of stool for ova and parasites involves three distinct procedures:

Answer 41

1. direct wet preparation 2. concentration technique 3. permanent staining

Question 42

it is necessary for the microscope to contain a specially designed ocular piece equipped with a measuring scale known as

Answer 42

ocular micrometer

Question 43

The ocular micrometer is a disk that is inserted into the _ of the micro- scope.

Answer 43

eyepiece

Question 44

primary purpose is to detect the presence of motile protozoan trophozoites

Answer 44

direct wet preparation

Question 45

added preservative in direct wet prep

Answer 45

saline or iodine

Question 46

% of saline in direct wet prep

Answer 46

0.85%

Question 47

A direct iodine wet preparation may be made to enhance the detail of protozoan _

Answer 47

cysts

Question 48

to aggregate parasites present into a small volume of the sample and to remove as much debris as possible that might hinder the labora- tory technician’s ability to see any parasites present clearly

Answer 48

concentration techniques

Question 49

2 types of concentration methods

Answer 49

- flotation - sedimentation

Question 50

most widely used sedimentation technique that provides good recovery of most para- sites and is easy to perform

Answer 50

Formalin–Ethyl Acetate Sedimentation Procedure

Question 51

it yields a cleaner preparation, making it easier for microscopic examination but some helminth eggs are very dense and will not float

Answer 51

Zinc Sulfate Flotation Technique

Question 52

to confirm the presence of protozoa cysts and/or trophozoites by staining intracellular organelles

Answer 52

permanent stains

Question 53

if a permanent stained smear is not performed, this parasite will likely be missed

Answer 53

Dientamoeba fragilis

Question 54

Helminth eggs or larvae are best detected and identified using a

Answer 54

concentration technique

Question 55

Two common stains used for routine O&P testing include

Answer 55

trichrome (Wheatley modifica- tion) and iron hematoxylin

Question 56

most widely used stain with a relatively long shelf life and the procedure is easy to perform

Answer 56

wheatley trichrome

Question 57

reveals excellent morphology of the intestinal protozoa

Answer 57

iron hematoxylin

Question 58

A modified iron hematoxylin stain has been developed that incorporates a _ step; this allows for the detection of acid-fast parasites

Answer 58

carbol fuchsin

Question 59

from which area can the Enterotest be used to collect specimens?

Answer 59

duodenum

Question 60

how many hours Enterost incubates

Answer 60

4 hours

Question 61

helpful for detecting E. histolytica

Answer 61

sigmoidoscopy material

Question 62

for the detection of Enterobius vermicularis

Answer 62

cellophane tape prep

Question 63

in cellophane tape prep, when does the specimen collected?

Answer 63

morning before the patient washes or defecates

Question 64

If malaria is suspected, it is best to prepare smears within _ of collection.

Answer 64

1 hour

Question 65

smear for frequently satisfactory screening purooses

Answer 65

thick smear

Question 66

smear that provides best biew of the malarial parasite in the RBCs and recommended for species indentification

Answer 66

thin smears

Question 67

two permanent stains commonly used

Answer 67

• Wright’s stain • Giemsa stain

Question 68

preferred stain because it allows for the detection of parasite detail necessary for species identification

Answer 68

giemsa stain

Question 69

to concentrate blood specimens sus- pected of containing low numbers of microfilariae

Answer 69

knott technique

Question 70

knott technique consist of 1ml of blood and _ of _

Answer 70

10 mL of 2% formalin

Question 71

specimen collected for the diagnosis of amebic conditions

Answer 71

Cerebrospinal fluid (CSF)

Question 72

recommended for the recovery of a number of parasites, including intracellular organisms such as Leishmania spp. and T. gondii.

Answer 72

Tissue and biopsy specimens

Question 73

sputum typically collected and tested from patients suspected of being infected by the lung fluke _

Answer 73

Paragonimus westermani

Question 74

specimen for Acanthamoeba keratitis

Answer 74

eye specimen

Question 75

is best diagnosed by the collection and examination of corneal scrapings.

Answer 75

Acanthamoeba keratitis

Question 76

t/f. Mouth scrapings are the sample of choice for the detection of E. gingivalis and Trichomonas tenax, whereas nasal discharge specimens are helpful for the recovery of parasites such as N. fowleri.

Answer 76

true

Question 77

Useful in the detection of Onchocerca volvulus

Answer 77

skin snips

Question 78

a technique used for the diagnosis of Chagas’ disease

Answer 78

xenodiagnosis