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MLSCI242 LAB > MLSCI340 Parasitology > Flashcards

MLSCI340 Parasitology Flashcards

1
Q

Collection instructions for O&P specimen examination

A
  • clean, dry container
  • do not let urine contaminate stool sample (ie. urinate first before collection)
  • collect from bloody/ slimy/ watery areas
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2
Q

Specimen interferences for O&P examination

A
  • bismuth
  • antibiotics
  • anti-malarial drugs
  • anti-diarrheal medicine
  • antacids
  • laxatives
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3
Q

Fixatives used in O&P examination

A
  • SAF liquid (yellow top)
  • buffered formalin (5% or 10%)
  • PVA (polyvinyl alcohol)
  • MIF
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4
Q

Explain collection/ handling of multiple specimens in O&P examination

A

If >1 specimens are requested, collect on alternate days WITHIN 10 DAYS

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5
Q

What kind of information is outlined on the Enteric pathogen history form that is relevant to O&P examinations ?

A
  • immune status (compromised ? acquired immunodeficiency syndrome ?)
  • travel history
  • raw shellfish consumption
  • immigaration
  • employment
  • close contact with Giardia lamblia/ Crypto cases
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6
Q

Significance, collection method, and common organisms detected in Duodenal Contents

A
  • used to diagnose GI tract infections
  • uses string test/ duodenal aspirates

= Giardia lamblia

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7
Q

Significance, collection method, and common organisms detected in Cellophane Tape Test/ Sticky Paddle

A
  • used to diagnose pinworm eggs (Enterobius vermicularis)
  • press tape along anal opening, then transfer to glass slide
  • morning collection
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8
Q

Significance, collection method, and common organisms detected in Urine and Urethra

A
  • detects urogenital infections

= Trichomonas vaginalis

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9
Q

Significance, collection method, and common organisms detected in Sputum

A
  • detects pneumoniae, Loeffler’s Syndrome

= Strongyloides, Entamoeba histolytica

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10
Q

Describe macroscopic O&P examination

A

detects proglottids and worms in areas of blood and mucus

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11
Q

Describe microscopic O&P examination (3)

A
  1. fresh wet mounts = detects motile Entamoeba histolytica (directional motility)
  2. wetmount concentrates (sedimentaion vs floatation) = recovery of cysts, coccidian oocytes, spores, hemlinth eggs, larvae…
  3. stained slides = 100X; allows more detail for ID; modified acid-fast always required
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12
Q

T or F: even when iodine is used in wetmount concentrates, organisms may still be cultured

A

FALSE; when iodine is used in wetmount concentrates, ORGANISMS ARE DEAD

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13
Q

Sedimentation vs Flotation concentration techniques

A

Sedimentation:
- formalin-ethyl acetate
- parasites in sedimentation layer
- 4 layers

Floatation:
- zinc sulfate
- parasites in surface film layer
- 3 layers

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14
Q

Pros and cons of Sedimentation Wetmounts

A

Sedimentation (formalin-ethyl acetate):
PROS
- Under 100X; allows more detail for ID
- Stable (formalin)
- Cheap
- Easy to perform

CONS
- too much iodine obscures helminth eggs

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15
Q

Pros and cons of Floatation Wetmounts

A

Floatation (zinc sulfate):
PROS
- parasites acquired from cleaner material (surface film)

CONS
- heavy eggs will sink
- must be read <30 min
- more technical

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16
Q

Modified Acid-Fast stains in O&P

A
  • modified ZN or Kinyoun stains = Cryptosporidium are bright pink
  • required for ALL O&P examination
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17
Q

T or F: Modified Acid-Fast stains are required in all O&P examinations

A

TRUE; Modified Acid-Fast stains are required in all O&P examinations

18
Q

Trichrome stains in O&P

A
  • protozoa = BLUE/GREEN to PURPLE CYTOPLASM
  • nuclei and inclusions (chromatoidal bars + RBCs) = BRIGHT PINK
  • background debris = green
19
Q

Iron-hematoxylin stains in O&P

A
  • shades of grey
20
Q

Modified Iron-hematoxylin stains in O&P

A
  • a modified acid-fast component is added
  • acid-fast organism = BRIGHT PINK
21
Q

What are Charcot-Leyden Crystals ? Why are they reported with O&P examinations ?

A
  • can indicate a systemic infection/ allergic response
  • look like slender “toothpicks”
  • formed from breakdown products of eosinophils
22
Q

Describe Acanthamoeba sp. infection

A
  • eye infections due to poor contact lens care, cutaneous infections or keratitis
  • found in tap water
  • chloride resistant (in pools)
23
Q

Describe ID of Acanthamoeba sp.

A
  • 7-day incubation: corneal scrapings OR contact lenses are inoculated into agar overlaid with E. coli = microscopic observation of trails in confluent E. coli
  • confirmed using PCR
  • calcofluor white for nonspecific fluorescence from corneal scrapings
24
Q

Green-based parasitology stain

A

Trichrome

25
Q

Full examination if a patient has this prior history

A

travel

26
Q

Common non-pathogen containing 1-8 nuclei in cyst

A

Entamoeba coli

27
Q

Causative agent of “itchy bum” (slang)

A

pinworm

28
Q

Organism identified by sticky paddle or cellophane tape test

A

Enterobius vermicularis

29
Q

Causative agent of cysticercosis

A

Taenia solium

30
Q

Causative agent of beaver fever

A

Giardia lamblia

31
Q

“fish tapeworm”; due to ingestion of poorly cooked freshwater fish

A

Diphyllobothrium latum

32
Q

Found in sputum in cases of hyperinfestation; “threadworm”

A

Strongyloides sterocoralis

33
Q

A possible corneal pathogen when you swim with contact lenses

A

Acanthamoeba sp.

34
Q

Which protozoan stage is considered infective and non-infective

A

Cyst = INFECTIVE
Trophozoite = non-infective

35
Q

Protozoan cyst contains 1-4 nuclei and the trophozoite may contain RBCs

A

Entamoeba histolytica

36
Q

Preservative used in the Edmonton zone for O&P examination

A

SAF; sodium acetate-acetic acid-formalin

37
Q

May cause bowel obstruction when worm burden is high; may require surgical intervention

A

Ascarcis lumbricoides

38
Q

Detection occurs with modified acid-fast staining (Kinyoun)

A

Cryptosporidium sp.

39
Q

Test used to directly detect Giardia lamblia from patient specimens without travel history

A

ELISA

40
Q

“Whipworm;” soil-transmitted helminth

A

Trichuris trichiura

41
Q

Classified as a flagellate BUT HAS NO FLAGELLA; associated with digestion of helminth eggs from E. vermicularis/ pinworm

A

Dientamoeba fragilis

MLSCI242 LAB (21 decks)

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