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PARASITOLOGY > Chapter 2 > Flashcards

Chapter 2 Flashcards

1
Q

Stool samples from patients whose therapy includes barium, bismuth, or mineral oil should be collected

A

prior to therapy or not until 5 to 7 days after the completion of therapy.

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2
Q

Collection of specimens from patients who have taken antibiotics or antimalarial medications should be

A

delayed for 2 weeks following therapy

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3
Q

Stool specimens should be collected in

A

a clean, watertight container with a tight-fitting lid.

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4
Q

The acceptable amount of stool required for parasite study is

A

2 to 5 g, often referred to as the size of a walnut.

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5
Q

Urine should not be allowed to contaminate the stool specimen because

A

it has been known to destroy some parasites.

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6
Q

Stool should not be retrieved from toilet bowl water because

A

free-living protozoa and nematodes may be confused with human parasites.

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7
Q

The specimen container should be labeled with the

A

patient’s name and identification number, the physician’s name, and the date and time of sample collection.

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8
Q

To demonstrate the motility of protozoan trophozoites, ____ is required.

A

a fresh specimen

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9
Q

Because trophozoites are usually found in liquid stool, it is recommended that liquid specimens be examined within

A

30 minutes of passage.

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10
Q

In keeping with stool consistency, semiformed specimens may yield a mixture of protozoan cysts and trophozoites and should be evaluated within

A

1 hour of passage.

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11
Q

Formed stool specimens are not likely to contain trophozoites; therefore, they can be held for

A

24 hours following collection.

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12
Q

FIXATIVES FOR PRESERVATION

A
  • Formalin
  • POLYVINYL ALCOHOL
  • SODIUM ACETATE FORMALIN
  • MODIFIED POLYVINYL ALCOHOL
  • ALTERNATIVE SINGLE-VIAL SYSTEMS
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13
Q

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

A

Fixatives

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14
Q

___ ideally preserves protozoan cysts

A

5% concentration

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15
Q

_____ preserves helminth eggs and larvae

A

10% concentration

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16
Q

Formalin may be routinely used for

A

direct examinations and concentration procedures, but not for permanent smears

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17
Q

Advantages of formalin

A
  • It is easy to prepare
  • It preserves specimens for up to several years
  • It has a long shelf life.
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18
Q

Disadvantages of formalin

A
  • Does not preserve parasite morphology adequately for permanent smears
  • Trophozoites and morphologic details of cysts and eggs may fade with time
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19
Q

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

A

Polyvinyl Alcohol

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20
Q

Polyvinyl Alcohol is most often combined with

A

Schaudinn solution, which usually contains zinc sulfate, copper sulfate, or mercuric chloride as a base

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21
Q

Trophozoites and cysts of the protozoa, as well as most helminth eggs, may be detected using this fixative.

A

Polyvinyl Alcohol

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22
Q

Advantages of Polyvinyl Alcohol

A
  • It can be used for preparation of a permanent stained smear
  • Long shelf life when stored at room temperature
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23
Q

Disadvantages of Polyvinyl Alcohol

A
  • Certain parasites is not as effective as when formalin is used
  • Schaudinn solution contains mercuric chloride
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24
Q

A viable alternative to the use of PVA and Schaudinn fixative

A

SODIUM ACETATE FORMALIN

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25
This preservative can be used for performing concentration techniques and permanent stained smears.
SODIUM ACETATE FORMALIN
26
Advantages of SODIUM ACETATE FORMALIN
* Easy to prepare * Long shelf life * Can be used for preparing smear
27
Disdvantages of SODIUM ACETATE FORMALIN
* Addition of albumin to the microscope slide may be necessary for adhesion * Protozoa is not clear
28
Mercury-based PVA are the use of substitute compounds containing copper sulfate or zinc sulfate
MODIFIED POLYVINYL ALCOHOL
29
provide better results than copper sulfate reagents
Zinc sulfate fixatives
30
Advantage of MODIFIED POLYVINYL ALCOHOL
Can be used for concentration methods and permanent stained | smears
31
Disadvantage of MODIFIED POLYVINYL ALCOHOL
Parasite identification is more difficult
32
formalin and mercury and can be used for concentration techniques and permanent stained smears
ALTERNATIVE SINGLE-VIAL SYSTEMS
33
M a c r o s c o p i c E x a m i n a t i o n
Color Consistency Gross appearance
34
M i c r o s c o p i c E x a m i n a t i o n
Direct Wet Preparation Concentration Method P e r m a n e n t S t a i n
35
Slide made with mixing a small portion of unfixed stool with saline or iodine
Direct Wet Preparation
36
provide the ability to detect small numbers of parasites that might not be detected using direct wet preparations
Concentration Method
37
Concentration Methods
* Formalin–Ethyl Acetate Sedimentation Procedure | * Zinc Sulfate Flotation Technique
38
The most widely used sedimentation technique is the
formalin–ethyl acetate sedimentation procedure.
39
The principle of this technique formalin–ethyl acetate sedimentation procedure.
is based on specific gravity.
40
process of formalin–ethyl acetate sedimentation procedure.
Ethyl acetate is added to a saline-washed formalin-fixed sample and the tube is then centrifuged.
41
Parasites are heavier than the solution and settle in the sediment of the tube, whereas fecal debris is usually lighter and rises to the upper layers of the test tube.
formalin–ethyl acetate sedimentation procedure.
42
advantage of formalin–ethyl acetate sedimentation procedure.
provides good recovery of most parasites and is | easy to perform.
43
The disadvantage of formalin–ethyl acetate sedimentation procedure.
is that the preparation contains more fecal debris than a flotation technique and is more challenging to the microscopist.
44
The zinc sulfate flotation technique is also based on differences in specific gravity between the sample debris, which in this case is heavy and sinks to the bottom of the test tube, and potential parasites, which are lighter and float toward the top of the tube.
Zinc Sulfate Flotation Technique
45
In this procedure, | zinc sulfate, with a specific gravity of ___, is used as the concentrating solution.
1.18 to 1.20
46
When the ___ is added to the specimen and centrifuged, the parasites float to the surface and can be skimmed from the top of the tube.
zinc sulfate
47
The advantage of Zinc Sulfate Flotation Technique is that
more fecal debris is removed and it yields a cleaner preparation, making it easier for microscopic examination.
48
The disadvantage of Zinc Sulfate Flotation Technique is that
some helminth eggs are very dense and will not float; therefore, some parasites will be missed.
49
Defined as a microscope slide that contains a fixed sample that has been allowed to dry and subsequently stained.
P e r m a n e n t S t a i n
50
Two common stains used for routine O&P testing include
trichrome (Wheatley modification) and iron hematoxylin.
51
STOOL SCREENING METHODS
Enzymeimmunoassay(EIA) Directfluorescentantibody(DFA) Membrane flow cartridge
52
OTHER INTESTINAL SPECIMENS
DuodenalMaterial SigmoidoscopyMaterial CellophaneTapePreparation
53
Enterotest
* The patient swallows a gelatin capsule that contains a coiled length of yarn. * The capsule dissolves in the stomach and the weighted string is carried to the duodenum. * The free end of the string is attached to the patient’s neck or cheek with tape. * After a 4-hour incubation period, the yarn is pulled back out of the patient. * The bilestained mucous material brought up on the string is then examined microscopically via wet preps and, if necessary, permanent stains.
54
Colon biopsy material may also be collected for examination.
Sigmoidoscopy Material
55
* The cellophane tape prep is the specimen of choice for the detection of Enterobius vermicularis (pinworm) eggs. * Adult female pinworms may also be seen.
Cellophane Tape Preparation
56
Blood
- Leishmania donovani, Trypanosoma spp.,Plasmodium spp., Babesia spp.
57
blood
* Thick and Thin Smears * Permanent Stains * Buffy Coat Slides * Cultures
58
CSF and Other Sterile Fluids
- Acanthamoeba spp., Naegleria spp., Toxoplasma gondii, Taenia solium cystecercus larvae, Echinococcus spp. ANTgTsclE
59
Tissue and Biopsy Specimens
Leishmania spp., T. gondii, Trypanosoma spp., Trichinella spiralis LTTT
60
Sputum
Paragonimus westermani, Strongyloides stercoralis PWSS
61
Urine and Genital Secretions
Schistosoma haematobium, Trichomonas vaginalis ST
62
Eye specimens
- Acanthamoeba keratitis, Loa loa
63
Mouth Scrapings and Nasal Discharge
- E. gingivalis and Trichomonas tenax, N. fowleri
64
Skin Snips -
Onchocerca volvulus
65
Culture Methods -
E. histolytica, T. vaginalis, Leishmania spp., T. cruzi, and T. gondii. ELTTT
66
Animal Inoculation and Xenodiagnosis -
Leishmania, Toxoplasma and | Trypanosoma.
67
Xenodiagnosis is a technique used for the diagnosis of
Chagas’ disease.
68
An uninfected is allowed to take a blood meal from the patient and the bug’s feces is then examined to observe for the presence of T. cruzi.
reduviid bug

PARASITOLOGY (3 decks)

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