EXERCISE 3: COLLECTION AND PRESERVATION OF STOOL SPECIMEN

Question 1

TRUE OR FALSE

During intestinal parasitosis, parasites are intermittently shed in the feces

Answer 1

TRUE

Question 2

most common procedure performed in the area of parasitology for diagnosis of intestinal parasitosis.

Answer 2

ova and parasites
(abbreviated as O & P)

Question 3

examined for the presence of
intestinal parasites in order to rule out or to consider parasitosis.

Answer 3

Stool specimens

Question 4

TRUE OR FALSE

Diagnosis of intestinal parasitosis relies largely on macroscopic and microscopic examination of stool specimen.

Answer 4

TRUE

Question 5

TRUE OR FALSE

A stool specimen should be examined before a patient’s intake of drugs or collected a week after intake.

Answer 5

TRUE

Question 6

TRUE OR FALSE

Certain medications such as anti-diarrheal, antacids, anti-malarial agents; and
substances such as bismuth and barium (as x-ray contrast medium) may leave
crystalline residues which can interfere with identification of parasites.

Answer 6

TRUE

Question 7

A- FIRST TRUE
B- SECOND TRUE
C- BOTH TRUE
D- BOTH FALSE

Oily laxatives such as castor oil, mineral oil, or suppositories also interfere with the
examination as they retard the motility of protozoan trophozoites, and distort
morphology of select parasites.

Antibiotics that affect the normal gastrointestinal flora usually increases the
number of protozoans for several weeks (i.e., 2 weeks), since they feed on
intestinal bacteria.

Answer 7

A

second statement, “usually decreases the number of protozoans”

Question 8

A- FIRST TRUE
B- SECOND TRUE
C- BOTH TRUE
D- BOTH FALSE

The fit of the lid is important to prevent accidental spillage of the specimen and
to maintain moisture within the specimen.

Integrity of the morphology of certain
parasites are affected by desiccation (removal of moisture).

Answer 8

C

Question 9

A- FIRST TRUE
B- SECOND TRUE
C- BOTH TRUE
D- BOTH FALSE

Urine may destroy protozoans especially the motile stages.

Toilet water and/or soil as they may contain free-living organisms
that can be mistaken for human parasites, thus, complicate
diagnosis of infections.

Answer 9

C

Question 10

Volume of the fecal sample for a formed stool

Answer 10

a thumb-sized specimen

Question 11

Volume of the fecal sample for a watery specimen.

Answer 11

1/2 teaspoon or 5-6 tablespoons

Question 12

A- FIRST TRUE
B- SECOND TRUE
C- BOTH TRUE
D- BOTH FALSE

For routine examination for parasites before treatment, a series of 5 fecal samples is considered minimum for adequate examination.

Fecal samples should be collected on separate days, if possible every other day,
or within a 10-day period.

Answer 12

B

first statement, “3 fecal samples”

Question 13

A- FIRST TRUE
B- SECOND TRUE
C- BOTH TRUE
D- BOTH FALSE

To ensure the recovery of parasitic organisms that are passed intermittently and
in fluctuating numbers, the examination of a minimum of three specimens
collected over a 7- to 10-day period is recommended.

2 specimens
collected from normal bowel movement and 1 specimen collected after
catharsis/purge.

Answer 13

C

Question 14

are prescribed in order to stimulate some “flushing action” within the
GIT, possibly allowing one to obtain more organisms for recovery and identification.

Answer 14

Cathartics

Question 15

TRUE OR FALSE

Oil-based cathartics should NOT be used since they retard the motility of trophozoites and distort the morphology of the parasites.

Answer 15

TRUE

Question 16

A- FIRST TRUE
B- SECOND TRUE
C- BOTH TRUE
D- BOTH FALSE

When a patient is suspected of having intestinal amoebiasis, 6 specimens is
recommended

Collected on separate days or
within 14-day period:

Answer 16

C

Question 17

A- FIRST TRUE
B- SECOND TRUE
C- BOTH TRUE
D- BOTH FALSE

3 specimens collected from normal bowel movement and 3 specimen collected after catharsis/purge is required for patients who have intestinal amoebiasis

For post-therapy examinations, 3 specimens are also recommended

Answer 17

C

Question 18

A- FIRST TRUE
B- SECOND TRUE
C- BOTH TRUE
D- BOTH FALSE

For protozoan infection, stool specimen must be
checked 3–4 weeks after therapy.

As for Taenia infection, fecal sample must be
examined 5–6 weeks after therapy.

Answer 18

C

Question 19

TRUE OR FALSE

The time limit recommendations are most relevant for the recovery and
identification of intestinal protozoa.

Answer 19

TRUE

Question 20

TRUE OR FALSE

Examination of liquid stool must be carried
out within 60 minutes of passage

Answer 20

30 minutes

Question 21

A- FIRST TRUE
B- SECOND TRUE
C- BOTH TRUE
D- BOTH FALSE

Soft/Semi-formed stool must be examined within of passage 24 hours

whereas, formed stool be examined at any time within 1 hour after passage as
immediate examination is not critical.

Answer 21

D

first statement, “1 hour”
second statement, “24 hours”

Question 22

A- FIRST TRUE
B- SECOND TRUE
C- BOTH TRUE
D- BOTH FALSE

protozoan cysts which due to
their cyst wall are more resistant to disintegration are found more commonly in
formed stools

most helminth eggs and larvae will survive for extended periods.

Answer 22

C

Question 23

TRUE OR FALSE

Although freshly passed stools are preferred for examination, if general time recommendation is not possible, preservatives should be used.

Answer 23

TRUE

Question 24

TRUE OR FALSE

Fecal sample should be submitted promptly to the hospital.

Answer 24

FALSE

“laboratory”

Question 25

A- FIRST TRUE B- SECOND TRUE C- BOTH TRUE D- BOTH FALSE Reasons for a lag time between specimen passage and examination in the lab include: 1. Transit distance or time for the specimen to reach the facility. 2. Workload in the laboratory.

Answer 25

C

Question 26

When employed, this method generally preserves protozoan cysts , and helminth eggs and larvae however, trophozoites are killed.

Answer 26

REFRIGERATION (3-5 C)

Question 27

TRUE OR FALSE prolonged refrigeration can bring about desiccation.

Answer 27

TRUE

Question 28

TRUE OR FALSE In chemical preservation and efficient stool preservation, fecal samples must be adequately mixed with selected preservative in a proportion of 1 part stool to 3 parts preservative.

Answer 28

TRUE

Question 29

An all-purpose fixative appropriate for helminth eggs and larvae, and for protozoan cysts, oocysts, and spores. But not suitable for some permanent stained smears like trichrome.

Answer 29

Formalin

Question 30

Easy to prepare, and has a long shelf life and suitable for concentration procedures. But Inadequate preservation of the morphology of protozoan trophozoites.

Answer 30

Formalin and MIF

Question 31

Suitable for acid-fast, safranin and chromotrope stains, and compatible with immunoassay detection kits. But can interfere with polymerase chain reaction after extended fixation time.

Answer 31

Formalin

Question 32

A- FIRST TRUE B- SECOND TRUE C- BOTH TRUE D- BOTH FALSE 2 concentrations of formalin commonly used: 5 % - recommended for preservation of protozoan cysts 10% - for helminth eggs and larvae

Answer 32

C

Question 33

Components (formalin): [5%] Formaldehyde (USP): ? Saline (0.85% NaCl): ?

Answer 33

Formaldehyde (USP): 50 ml Saline (0.85% NaCl): 950 ml

Question 34

Components (formalin): [10%] Formaldehyde (USP): ? Saline (0.85% NaCl): ?

Answer 34

Formaldehyde (USP): 100 ml Saline (0.85% NaCl): 900 ml

Question 35

TRUE OR FALSE Formaldehyde is normally purchased as 37-40% solution; however, for dilution, it should be considered to be 100%.

Answer 35

TRUE

Question 36

TRUE OR FALSE Buffered Formalin: 1 liter of 5% or 10% formalin 0.8 g of phosphate buffer salt mixture - 6.10 g Na2HPO4 - 0.15 g NaH2PO4

Answer 36

TRUE

Question 37

preservative is prepared in 2 stock solutions and mixed immediately before use.

Answer 37

MIF (Merthiolate-Iodine-Formaldehyde)

Question 38

Good stain preservative for most kinds and stages of parasites found in feces. But not suitable for some permanent stained smears like trichrome.

Answer 38

MIF

Question 39

A- FIRST TRUE B- SECOND TRUE C- BOTH TRUE D- BOTH FALSE [MIF] Useful for field surveys but Iodine interferes with other stains and fluorescence. Iodine may cause distortion of protozoa.

Answer 39

C

Question 40

[MIF] COMPONENTS: Solution I (stored in brown bottle) Distilled water 50 ml Formaldehyde (USP) 5 ml Thimerosal (tincture of merthiolate, 1:1,000) 40 ml Glycerin 1 ml Solution II – Lugol’s solution (good for several weeks in tightly stoppered brown bottle) Distilled water 100 ml Potassium iodide crystals 10 g Iodine crystals 5 g Procedure: Combine 9.4 ml of solution I with 0.6 ml of solution II.

Answer 40

IMEMORIZE MO

Question 41

TRUE OR FALSE [MIF] preserved specimen, if undisturbed within 24 h, form 3 well-defined layers: upper, interface, bottom

Answer 41

TRUE

Question 42

[mif] clear orange fluid, consists mainly of formalin, merthiolate and water; it does NOT trap eggs and protozoa

Answer 42

Upper

Question 43

[mif] thick, pale orange or creamy yellow, usually 1-2 mm thick; may trap some protozoa and helminth eggs

Answer 43

interface

Question 44

[mif] consists of deeper staining particulate matter; eggs and protozoa are found throughout this layer

Answer 44

bottom

Question 45

Suitable for both concentration procedures and permanent stained smears but poor adhesive properties (requires additive, e.g., albumin-glycerin, for adhesion of specimens to the slides).

Answer 45

SAF (Sodium Acetate-Acetic Acid-Formalin)

Question 46

Easy to prepare or commercially available from a number of suppliers, and has a long shelf life but Protozoan morphology with trichrome stain not as clear as with PVA or Shaudinn’s smears. Hematoxylin staining gives better results.

Answer 46

SAF

Question 47

Compatible with immunoassay detection kits and Does not contain mercury compounds but May be a bit more difficult to use and More difficult for inexperienced workers to use

Answer 47

SAF

Question 48

Components: Sodium acetate 1.5 g Acetic acid, glacial 2.0 ml Formaldehyde, 37-40% solution 4.0 ml Distilled water 92.0 ml

Answer 48

SAF (Sodium Acetate-Acetic Acid-Formalin)

Question 49

1. Mix equal parts of egg white and glycerin. 2. Place 1 drop on microscope slide, and 1 drop of SAF-preserved fecal sediment. 3. After mixing, allow the smear to dry at room temperature for 30 min prior to staining

Answer 49

Mayer’s Albumin

Question 50

Components: [I. Mercuric Chloride, Saturated Aqueous Solution:] Mercuric chloride 110 g Distilled water 1,000 ml Procedure: 1. Use a beaker as water bath. 2. Boil until mercuric chloride is dissolved. 3. Let stand several hours until crystals form. [II. Schaudinn’s Fixative (Stock Sol’n):] Mercuric Chloride, sat. aq. 600 ml Ethyl alcohol, 95% 300 ml *Immediately before use, add 5 ml glacial acetic acid per 100 ml stock solution.

Answer 50

WALA LANG IMEMORIZE MO LANG DIN ULIT, OKAY? SIGE JINJJARO (*insert sir culliao's voice*)

Question 51

Provides excellent preservation of morphology of protozoan trophozoites and cysts but Inadequate preservation of helminth eggs and larvae, coccidian and microsporidia.

Answer 51

PVA (Polyvinyl Alcohol)

Question 52

Long shelf life (months to years) tightly sealed containers at room temperature and allows the specimen to be shipped to any laboratory for subsequent examination. But contains mercuric chloride which may cause disposal problems, Difficult to prepare in the laboratory, May turn white and gelatinous when it begins to dehydrate or when refrigerated and Cannot be used with immunoassay detection kits.

Answer 52

PVA (Polyvinyl Alcohol)

Question 53

[PVA] Components: PVA 10.0 g Ethyl Alcohol, 95% 62.5 ml Mercuric chloride, sat. aq. 125.0 ml Acetic acid, glacial 10.0 ml Glycerin 3.0 ml Procedure: 1. Mix the liquid ingredients in a beaker, then add the PVA powder. 2. Cover and allow PVA to soak overnight. Heat the solution slowly to 75 C. 3. When this temperature is reached, remove the beaker and swirl the mixture for 30 secs until a homogeneous, slightly milky solution is obtained.

Answer 53

BEH IMEMORIZE MO NALANG OR FAMILIARIZE WHATEVER PAGOD NAKO :))

Question 54

TRUE OR FALSE Stool O and P is a routine laboratory procedure performed for diagnosis of intestinal parasitosis.

Answer 54

TRUE

Question 55

TRUE OR FALSE A thumb-sized specimen of formed stool is considered sufficient to perform routine parasitologic procedures such as O and P.

Answer 55

TRUE

Question 56

TRUE OR FALSE Ideally, a single specimen is sufficient to conclude whether or not a patient has intestinal parasitosis.

Answer 56

FALSE

Question 57

TRUE OR FALSE With the exception of oil-based ones, cathartics allow higher yield of parasites, hence better diagnosis of parasitosis.

Answer 57

TRUE

Question 58

Information on the specimen container should match those that are found in the requisition form during submission of a fecal sample.

Answer 58

TRUE