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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
Q

This preservative can be used for performing concentration techniques and permanent stained smears.

A

SODIUM ACETATE FORMALIN

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26
Q

Advantages of SODIUM ACETATE FORMALIN

A
  • Easy to prepare
  • Long shelf life
  • Can be used for preparing smear
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27
Q

Disdvantages of SODIUM ACETATE FORMALIN

A
  • Addition of albumin to the microscope slide may be necessary for adhesion
  • Protozoa is not clear
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28
Q

Mercury-based PVA are the use of substitute compounds containing copper sulfate or zinc sulfate

A

MODIFIED POLYVINYL ALCOHOL

29
Q

provide better results than copper sulfate reagents

A

Zinc sulfate fixatives

30
Q

Advantage of MODIFIED POLYVINYL ALCOHOL

A

Can be used for concentration methods and permanent stained

smears

31
Q

Disadvantage of MODIFIED POLYVINYL ALCOHOL

A

Parasite identification is more difficult

32
Q

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

A

ALTERNATIVE SINGLE-VIAL SYSTEMS

33
Q

M a c r o s c o p i c E x a m i n a t i o n

A

Color
Consistency
Gross appearance

34
Q

M i c r o s c o p i c E x a m i n a t i o n

A

Direct Wet Preparation
Concentration Method
P e r m a n e n t S t a i n

35
Q

Slide made with mixing a small portion of unfixed stool with saline or iodine

A

Direct Wet Preparation

36
Q

provide the ability to detect small numbers of parasites that might not be detected using direct wet preparations

A

Concentration Method

37
Q

Concentration Methods

A
  • Formalin–Ethyl Acetate Sedimentation Procedure

* Zinc Sulfate Flotation Technique

38
Q

The most widely used sedimentation technique is the

A

formalin–ethyl acetate sedimentation procedure.

39
Q

The principle of this technique formalin–ethyl acetate sedimentation procedure.

A

is based on specific gravity.

40
Q

process of formalin–ethyl acetate sedimentation procedure.

A

Ethyl acetate is added to a saline-washed formalin-fixed sample and the tube is then centrifuged.

41
Q

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.

A

formalin–ethyl acetate sedimentation procedure.

42
Q

advantage of formalin–ethyl acetate sedimentation procedure.

A

provides good recovery of most parasites and is

easy to perform.

43
Q

The disadvantage of formalin–ethyl acetate sedimentation procedure.

A

is that the preparation contains more fecal debris than a flotation technique and is more challenging to the microscopist.

44
Q

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.

A

Zinc Sulfate Flotation Technique

45
Q

In this procedure,

zinc sulfate, with a specific gravity of ___, is used as the concentrating solution.

A

1.18 to 1.20

46
Q

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.

A

zinc sulfate

47
Q

The advantage of Zinc Sulfate Flotation Technique is that

A

more fecal debris is removed and it yields a cleaner preparation, making it easier for microscopic examination.

48
Q

The disadvantage of Zinc Sulfate Flotation Technique is that

A

some helminth eggs are very dense and will not float; therefore, some parasites will be missed.

49
Q

Defined as a microscope slide that contains a fixed sample that has been allowed to dry and subsequently stained.

A

P e r m a n e n t S t a i n

50
Q

Two common stains used for routine O&P testing include

A

trichrome (Wheatley modification) and iron hematoxylin.

51
Q

STOOL SCREENING METHODS

A

Enzymeimmunoassay(EIA)
Directfluorescentantibody(DFA)
Membrane flow cartridge

52
Q

OTHER INTESTINAL SPECIMENS

A

DuodenalMaterial
SigmoidoscopyMaterial
CellophaneTapePreparation

53
Q

Enterotest

A
  • 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
Q

Colon biopsy material may also be collected for examination.

A

Sigmoidoscopy Material

55
Q
  • The cellophane tape prep is the specimen of choice for the detection of Enterobius vermicularis (pinworm) eggs.
  • Adult female pinworms may also be seen.
A

Cellophane Tape Preparation

56
Q

Blood

A
  • Leishmania donovani, Trypanosoma spp.,Plasmodium spp., Babesia spp.
57
Q

blood

A
  • Thick and Thin Smears
  • Permanent Stains
  • Buffy Coat Slides
  • Cultures
58
Q

CSF and Other Sterile Fluids

A
  • Acanthamoeba spp., Naegleria spp., Toxoplasma gondii, Taenia solium cystecercus larvae, Echinococcus spp.

ANTgTsclE

59
Q

Tissue and Biopsy Specimens

A

Leishmania spp., T. gondii, Trypanosoma
spp., Trichinella spiralis

LTTT

60
Q

Sputum

A

Paragonimus westermani, Strongyloides stercoralis

PWSS

61
Q

Urine and Genital Secretions

A

Schistosoma haematobium, Trichomonas
vaginalis

ST

62
Q

Eye specimens

A
  • Acanthamoeba keratitis, Loa loa
63
Q

Mouth Scrapings and Nasal Discharge

A
  • E. gingivalis and Trichomonas tenax, N. fowleri
64
Q

Skin Snips -

A

Onchocerca volvulus

65
Q

Culture Methods -

A

E. histolytica, T. vaginalis, Leishmania spp., T. cruzi, and T. gondii.

ELTTT

66
Q

Animal Inoculation and Xenodiagnosis -

A

Leishmania, Toxoplasma and

Trypanosoma.

67
Q

Xenodiagnosis is a technique used for the diagnosis of

A

Chagas’ disease.

68
Q

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.

A

reduviid bug

PARASITOLOGY (3 decks)

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