PRELIMS Flashcards
What is the most common specimen in the laboratory for stool examination?
Stool
What type of container is recommended for stool specimen collection?
Clean, wide-mouth plastic containers with tight-fitting lids
What factors should be considered during stool specimen collection?
- Intake of certain medicines (antacids, anti-diarrheals, barium, bismuth, laxatives)
- Amount of stool collected
- Presence of contaminants
- Age of stool sample
What are the three main types of stool examination?
- Physical
- Microscopic
- Chemical
What does the physical examination of stool involve?
Color and consistency
Fresh, unpreserved stool specimens are preferred.
How is stool consistency categorized?
- Formed
- Soft
- Loose
- Watery
What does black stool indicate?
- Bleeding in the upper gastrointestinal tract
- iron / bismuth subsalicytes
What does red stool indicate?
- Bleeding from the lower gastrointestinal tract
- red dye, food, drink
- hemorrhoids
- This is also referred to as hematochezia.
What color of stool suggests a lack of bile?
White or clay-colored stool.
What does yellowish stool indicate?
- Inability to digest fats or oils properly
- small intestinal infx
What is the purpose of chemical examination in stool analysis?
Detection of occult or small bleeding.
What is the principle behind guaiac-based occult blood testing (gFOBT)?
Detect pseudoperoxidase activity of hemoglobin.
What is the main principle of the fecal immunochemical test (FIT)?
Antigen-antibody reaction specific to hemoglobin in blood from the lower gastrointestinal tract.
What are the common techniques used in microscopic examination of stool?
- Direct Wet Film
- Concentration Techniques (sedimentation and flotation)
What does the direct wet film technique detect?
Trophic form of amoeba and flagellates.
What is the goal of concentration techniques in stool examination?
Separate protozoan cysts and helminth eggs from the bulk of fecal matter.
What reagents are used in the acid ether concentration technique?
- 40% Hydrochloric acid
- Ether
What is the main reagent in the formalin ether/ethyl acetate technique (FECT)?
Formalin and ether.
What is the specific gravity range for zinc sulfate flotation technique?
1.18 - 1.20.
What is the purpose of the Baermann apparatus?
To yield a good concentration of living larvae of Strongyloides stercoralis.
What is the Kato-Katz method used for?
Assessing the intensity of infection for soil-transmitted helminths.
What type of specimen is best for recovering Trichomonas vaginalis?
Urine.
What is the best specimen for diagnosing Naegleria fowleri?
Cerebrospinal fluid.
What staining technique is used for coccidians like Cryptosporidium?
Modified Acid-fast staining (Kinyoun method).
What is the significance of the buffy coat films in blood examination?
Concentrates Trypanosoma and Leishmania species.
What does the Harada-Mori test tube culture method utilize?
Test tubes and filter paper strips.
Presence of reddish color in loose stool?
- red dye, foods,drinks
- bleeding lower gut / rectum
Fill in the blank: The stool should be broken up with an _______.
applicator stick.
True or False: The stool culture methods can identify species between Hookworm and Strongyloides.
True.
Greenish stool is caused by …
- green dye / vegetables
- antibiotics
- bacterial infection
least used exam for stool
chemical exam
refers to degree of moisture of stool
consistency
Bright red blood or bloody mucus in loose
stool is suggestive of
intestinal parasitic
infection
The surface of the stool should be examined for
presence of parasites:
- pinworms
- ascaris
- tapeworm proglottids
Pinworms can be found
?
@ anal
ascaris can be found at ?
vomit or stool
Bleeding in excess of _______ of stool considered significant but not necessarily present with signs of bleeding
2.5 mL per 150 gm
Easily affected by
nonhuman heme & dietary peroxidases
indicates positive result at gFOBT
blue coloration
principle of FIT
Antigen-Antibody reaction, specific
to Hgb in blood from lower GIT
causes of FALSE-POSITIVE results in gFOBT
- Ingestion of nonhuman heme (meat products)
- Ingestion of peroxidases (broccoli)
- Ingestion of non-GI blood (epistaxis /nosebleed/)
- Use of: aspirin, NSAIDS, or anticoagulant med
causes of FALSE-POSITIVE results in FIT TEST
- Use of: aspirin, NSAIDS, or anticoagulant med
causes of FALSE-NEGATIVE results in FIT TEST
- Bleeding from upper GIT or proximal lower GIT
causes of FALSE-NEGATIVE results in GFOBT
- Ingestion of antioxidants (peroxidase affected)
Used to detect parasites and other significant fecal constituents
MICROSCOPIC EXAM
DIRECT WET FILM IS USED TO DETECT ?
TROPHIC FORM of AMOEBA &
FLAGELLATES
PROCEDURE OF DIRECT WET FILM EXAM
A small portion of feces is mixed with
a drop of NORMAL SALINE on a clean
slide and a cover slip is placed on
prep.
After examining an unstained film,
Iodine may be added to stain the
CYSTS
What kills trophs in direct wet film exam
Iodine
What is mixed in direct wet film to detect cysts
Normal saline
What does CONCENTRATION TECHNIQUE aims to do / goal
separate protozoan cysts & helminth
eggs from the bulk of fecal matter through differences in gravity
what are the 2 techniques of CONCENTRATION TECHNIQUE
- sedimentation
- flotation
Sedimentation techniques;
- acid ether CT
- formalin ether / ethyl acetate technique
what parasite does AECT recover?
- TRICHURIS
- CAPILLARIA
- TREMATODE EGGS (esp. Schistosoma)
main reagents of FECT
formalin & ether (ethyl acetate)
what parasite does FECT recover?
Helminth eggs & Protozoan
cysts
Ethyl Acetate is more efficient for the recovery of
Giardia Cysts
used to preserve stool in FECT
Formalin-preserved and
PVA-preserved stool
List all flotation techniques
- zinc sulfate F.
- brine F.
- Sheathers sugar F.
list all common stains
- iron hematoxylin
- trichrome
- periodic acid schiff
- chlorazol black e
What is the main reagent used in Zinc Sulfate flotation?
33% Zinc Sulfate Solution
What is the ideal specific gravity of the Zinc Sulfate solution?
1.18 - 1.20
What happens if parasites are exposed to higher specific gravity in Zinc Sulfate flotation?
Distortion and shrinkage of protozoan cysts and thin-walled nematode eggs may occur.
what can CSF diagnose
- naegleria fowleri
- trypanosoma cruzi
- trypanosoma brucei complex
- parastrongylus cantonensis
What is the main reagent used in brine flotation?
Saturated table salt (NaCl)
What is mixed with the stool in brine flotation?
brine solution
technique which has no need for centrifugation
brine flotation
technique where eggs of Hookworm and Schistosoma are shrunken.
brine flotation
For which type of eggs is brine flotation not useful?
Operculated eggs (Clonorchis, Opistorchis, & Heterophyids) because they won’t float.
process of CSF specimen
centrifuged at 7,000g for 10mins
What is the main reagent used in Sheather’s sugar flotation?
Boiled sugar preserved with Phenol
parasites recovered in URINE
- trichomonas vaginalis
- schistosoma haematobium
- wuchereria bancrofti
What is Sheather’s sugar flotation considered best to recover for?
Coccidian oocysts (ccc)
Name three types of Coccidian oocysts that Sheather’s sugar flotation can recover.
- Cryptosporidium
- Cyclospora
- Cystoisospora
species in blood at some point
- Helminthic parasites (filarial worms)
- protozoan p (plasmodium, trypanosoma, babesia)
What is the purpose of stool culture methods?
Identifying species between Hookworm and Strongyloides
What can a stool with a positive culture indicate?
Presence of Hookworm ova and/or Strongyloides Rhabditiform larva
Mixing stools positive with ova/larva with moistened soil or granulated charcoal
(SIMULATION OF NATURE)
coproculture
What procedure is used to harvest larvae in coproculture?
Baermann procedure
What does the Harada-Mori or test tube culture method utilize?
Test tubes and filter paper strips
- designed to facilitate the movement of larvae for easier recovery.
What is the process in the Harada-Mori method after applying positive stool?
Place filter paper in a test tube with 7 mL of boiled/distilled water
In the Harada-Mori method, where do Strongyloides larvae move?
Strongyloides larvae may move upward and can be recovered at the upper end
True or False: Stool cultures should be refrigerated.
False
What type of larvae can be cultured until Filariform Larva develops?
Hookworm ova and/or Strongyloides Rhabditiform larva
What is a common use for stool cultures besides Hookworm and Strongyloides identification?
Identifying Trichostrongylus sp.
stains used in blood specimen
gemsia & wright stains
What is the HARADA-MORI method?
It is a test tube culture method that makes use of test tubes and filter paper strips.
How is a positive stool sample prepared in the HARADA-MORI method?
Positive stool is applied to the filter paper and placed into a test tube with 7 mL of boiled or distilled water.
What happens to the filariform larva in the HARADA-MORI method?
The filariform larva moves downward against the upward movement of water and can be recovered from the water or at the bottom of the tube.
How does Strongyloides larva behave in the HARADA-MORI method?
Strongyloides larva may also move upward and can be recovered at the upper end of the test tube.
What should be noted about stool cultures in the HARADA-MORI method?
Stool cultures shouldn’t be refrigerated.
parasites found in blood
trypanosoma & leishmania
Knotts concentration procedure
microfilaria, 1ml + 10ml of 2% Formalin
Buffy coat layers stains
- gemsia
- wright
parasites recovered in sputum
- migrating larvaes of; Ascuris, Strongloides, & hookworm
- paragonimus ova
- echinococcus granulosus hooklet from PHC
- protozoans (e. histolytica, cryptosporidium)
consistencies of stool in macroscopic exam in sputum
serous, mucous, bloody
what does yellow color of stool of sputum indicate
pus
greenish tint of sputum indicates?
pseudomonas
microscopic examination in sputum
- wet amt using SALINE / IODINE SOLXN
- sputum con. using 3% NAOH
duodenal aspirate retrieves which parasites
- giardia lamlia
- strongyloides stercoralis
ENTERO TEST/ STRING TEST
yarn left at duodenum for 4hrs, retrieved with mucoidal material clinging to spring
parastrongylus cantonensis is correlated with CSF what
eusinophilia
what will be perished within 20mins in examination of CSF
TRYPOMASTIGOTES & NAEGLARIA TROPHS
specimen useful for the diagnosis of TRICHINELLA SPIRALIS
MUSCLE biopsy
