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MLSCI 340 > Special Lab - Parasitology > Flashcards

Special Lab - Parasitology Flashcards

1
Q

D. latum

A
  • megaloblastic anemia; competes with host for vit. B12
  • fish tapeworm
  • freshwater fish infection
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2
Q

Echonococcus granulosus

A
  • smallest of all tapeworms; 3-5 proglottids
  • suckers stick to intestinal wall
  • humans are accidental hosts from infected dogs
  • often lodge in liver
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3
Q

T. saginata/solium

A
  • T saginata = limited to intestinal tract
  • T solium = cysticercosis if egg ingested by man instead of pig; larvae invades voluntary muscle, CNS, and eyes
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4
Q

Collection Instructions for OAP examination

A
  • 2 wks before collection = no laxatives, any bismuth, barium sulfate, antacids, antibiotics
  • label properly
  • fill to line
  • clean, dry container
  • don’t contaminate with toiler water or urine
  • must refrigerate
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5
Q

interferences (stool; OAP)

A

barium, mineral oil, medications, antibiotics, bismuth

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6
Q

fixative used and ratio of preservative to feces

A

sodium actic acid formalin (SAF)
PVA fixative useful for liquid specimens
3 parts fixative to 1 part stool

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7
Q

number of specimens and timing for stool collection (OAP)

A
  • every other day for outpatients (3 minimum)
  • inpatients = daily, collected for 3 days
  • complete all collections within ten days
    some parasites not in stool everyday

NOTE: take specimens to lab the day it was collected;

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8
Q

pinworm colelction

A
  • collect first thing in morning before bowel movement (don’t wipe area first)
  • full first and last name, healthcare number, date and time of collection
  • sticky side close to anus
  • take specimen to lab the day of and ASAP
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9
Q

All routine requests for stool culture/enteric bacterial pathogens are screened for…

A

STEC, Campy, Salmonella, Shigella

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10
Q

When do we test for Yersinia, Vibrio, Aeromonas, Plesiomonas?

A

only if appropriate clinical, exposure, or travel history is provided

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11
Q

when do we reject OAP samples?

A
  • mislabelled or unlabelled specimen/req
  • multiple specimens on same day
  • leaking specimens
  • specimens with barium or oil noted in the stool
  • patient with a previous positive test result within last 7 days
  • insufficient quantity
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12
Q

duodenal contents

A
  • collected by string test or duodenal aspirates
  • if specimen cannot be examined within 2 hrs, fixed in 5-10% formalin
  • S. sterocoralis, G. duodenalis, Cryptosporidium sp
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13
Q

cellophane or take test/sticky paddle

A
  • surface sample from perianal skin; anal impression smear
  • sample collected after being asleep or first thing in morning
  • 4-6 consecutive neg tests before ruled out
  • E. vermicularis

NOTE: can be found in other specimens like urine or feces but not best there

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14
Q

urien for OAP

A
  • unpreserved
  • filarial infections
  • must be centrifuged before examination
  • membrane filter for Schistosoma haemotobium
  • T. vaginalis
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15
Q

urethra/vaginal (OAP)

A
  • saline swab (NO charcoal)
  • plastic envelope for culture
  • don’t refrigerate so motile capabilities can’t be lost; direct wet smear (Trich)
  • fluorescence
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16
Q

sputum (OAP)

A
  • direct wet smear; fluorescence also available
  • is sputum thick, use NaOH (BUT don’t use if Entamoeba sp. or Trichomonas tenax)
  • Strongyloides in hyperinfestation stat
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17
Q

microscopic exam for OAP (3)

A
  • fresh; direct wet mount = rare! motility; ID of E. histolytica vs E. coli
  • indirect = examination after concentration (formalin-ethyl acetate sedimentation most common); removes as much debris as possible; 10x or 40x; iodine for better visualization
  • stained = 100x for more detail; mod. acid fast always required; confirms ID/diagnosis of intestinal protozoan infections
18
Q

sedimentation

A
  • formalin-ethyl acetate
  • allow exam + recognition of detailed organism morph under oil immersion; int protozoa
  • EA layer, debris plug, formalin, sediment (parasites sit here at bottom)
  • reagent = lower SG
  • cheap reagents, easy to perform, widest range of orgs, stable (formalin)
  • large amt of background debris
19
Q

flotation

A
  • zinc sulfate
  • parasites float on high density reagent (higher SG)
  • surface film (parasites), zinc sulfate, sediment at bottom
  • cleaner concentrate
  • tech. more difficult, must be read <30 mins, heavy eggs distorted or just sink
20
Q

modified acid fast

A
  • ID of intestinal conidia
  • pink
  • KINYON
    = Cryptosporidium
  • needed for all mic exams (OAP)
21
Q

Trichrome

A
  • background dberis; green
  • blue to green cytoplasm in parasites
  • ID of intestinal microsporidia
22
Q

iron hematoxylin

A
  • shades of grey
  • can stain intracell. and nuclear structures dark (compared to cytoplasm)
23
Q

mod. iron hematoxylin

A
  • IH stain with modified acid fast stain
  • bright pink for acid fast organisms
24
Q

acid fastness

A

a physical property that gives a bacterium the ability to resist decolorization by acids during staining procedures. This means that once the bacterium is stained, it cannot be decolorized using acids routinely used in the process

25
Q

methods used for OAP examination when patient has good immune system and no travel histoy

A
  • ELISA = G. lamblia, Cryptosporidium
  • direct fluorescent Ab = monoclonal Ab stains for G. lamblia, Cryptosporidium; ID Confirmation due to high costs; highly specific and sensitive
26
Q

Charcot Leyden crystals

A

slender crystals shaped like a double pyramid with pointed ends
breakdown products of eosinophils
elevated w parasitic infection or allergy

27
Q

Acanthomeoba sp.

A
  • chlorine resistant, tap-water
  • corneal scrapings
28
Q

Acanthamoeba identification

A
  • ID requires culture on non-nutrient plate; confluent growth of E. coli for food
  • calcofluor white can help in screening
29
Q

non-infective stage for protozoa

A

toph
cyst = infective stage

30
Q

Entamoeba coli

A
  • cyst = 1-8 nuclei
  • more circular troph
  • found in contaminated water; non-pathogenic
  • eccentric karyosomes
31
Q

E. histolytica

A
  • 1-4 nuclei in cyst
  • troph = more pointed; knows where its going (progressive, unidirectional motility); RBCs present for definitive ID
  • notifiable disease
  • fecal-oral
  • E. dispar visually identical and is a non-pathogen
  • diagnosis needs travel history outside of Canada
  • chromatid bodies; central karyosomes
  • cigar-shaped chromatoidal bars
32
Q

G. lamblia

A
  • contaminated water or food or intimate direct contact
  • feces (duodenal contents or enterotest)
  • wet mount for motility, ELISA, DFA
  • monkey face, bilateral symmetry
  • 4 pairs of flagella
  • explosive diarrhea
  • notifiable
33
Q

Dientamoeba fragilis

A
  • common organism; source unknown
  • flagellate but no flagella
  • garbage can appearance
  • no cyst stage
34
Q

Blastomyces hominis

A
  • last resort for physicians
35
Q

Endolimax nana

A
  • non-pathogen
  • informs us that patient has been in contact w dirty water
36
Q

Iodamoeba butschii

A
  • closely resemble E. nana
  • non-patho
37
Q

Cryptosporidium

A
  • contam. water, calves
  • mod. Kinyon (oocyst), ELISA, DFA
  • resistant to chlorine (oocyst)
  • notifiable
38
Q

Schistosoma sp.

A
  • blood flukes
  • top 3 cause of death worldwide
  • travel required
  • stool = mansoni and japonicum
  • urine = haemotobium
  • lateral, rose thorn spine = mansoni
  • terminal spine = haemotobium
  • crooked finger spine = japonicum
39
Q

Ascaris lumbricoides

A
  • fecal-oral route
  • tropical/temperate areas
  • most common and largest roundworm
  • deworming programs
  • high number of worms may require surgery
40
Q

hookworm

A
  • necator (new world) and ancylostama (old world)
  • found in poor sanitation and areas where ppl go barefoot (larvae can penetrate skin)
  • anemia bc worm secretes an anticoag
  • rarely found in stool bc attaches to intestinal wall
41
Q

Trichuris trichiura

A
  • whipworm
  • confined to intestinal tract
  • football shaped egg
  • warmer climates
42
Q

Stronglyoides stercoralis

A
  • threadworm
  • can exist without human host
  • autoinfection life cycle = can persist for decades
  • females are parthenogenic (no fertilization necessary for repro)

MLSCI 340 (16 decks)

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