EXERCISE 3: COLLECTION AND PRESERVATION OF STOOL SPECIMEN Flashcards
TRUE OR FALSE
During intestinal parasitosis, parasites are intermittently shed in the feces
TRUE
most common procedure performed in the area of parasitology for diagnosis of intestinal parasitosis.
ova and parasites
(abbreviated as O & P)
examined for the presence of
intestinal parasites in order to rule out or to consider parasitosis.
Stool specimens
TRUE OR FALSE
Diagnosis of intestinal parasitosis relies largely on macroscopic and microscopic examination of stool specimen.
TRUE
TRUE OR FALSE
A stool specimen should be examined before a patient’s intake of drugs or collected a week after intake.
TRUE
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.
TRUE
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.
A
second statement, “usually decreases the number of protozoans”
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).
C
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.
C
Volume of the fecal sample for a formed stool
a thumb-sized specimen
Volume of the fecal sample for a watery specimen.
1/2 teaspoon or 5-6 tablespoons
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.
B
first statement, “3 fecal samples”
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.
C
are prescribed in order to stimulate some “flushing action” within the
GIT, possibly allowing one to obtain more organisms for recovery and identification.
Cathartics
TRUE OR FALSE
Oil-based cathartics should NOT be used since they retard the motility of trophozoites and distort the morphology of the parasites.
TRUE
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:
C
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
C
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.
C
TRUE OR FALSE
The time limit recommendations are most relevant for the recovery and
identification of intestinal protozoa.
TRUE
TRUE OR FALSE
Examination of liquid stool must be carried
out within 60 minutes of passage
30 minutes
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.
D
first statement, “1 hour”
second statement, “24 hours”
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.
C
TRUE OR FALSE
Although freshly passed stools are preferred for examination, if general time recommendation is not possible, preservatives should be used.
TRUE
TRUE OR FALSE
Fecal sample should be submitted promptly to the hospital.
FALSE
“laboratory”
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.
C
When employed, this method generally
preserves protozoan cysts , and helminth eggs and larvae however, trophozoites are
killed.
REFRIGERATION (3-5 C)
TRUE OR FALSE
prolonged refrigeration can bring about desiccation.
TRUE
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.
TRUE
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.
Formalin
Easy to prepare, and has a long shelf
life and suitable for concentration
procedures. But Inadequate preservation of the
morphology of protozoan
trophozoites.
Formalin and MIF
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.
Formalin
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
C
Components (formalin):
[5%]
Formaldehyde (USP): ?
Saline (0.85% NaCl): ?
Formaldehyde (USP): 50 ml
Saline (0.85% NaCl): 950 ml
Components (formalin):
[10%]
Formaldehyde (USP): ?
Saline (0.85% NaCl): ?
Formaldehyde (USP): 100 ml
Saline (0.85% NaCl): 900 ml
TRUE OR FALSE
Formaldehyde is normally purchased as
37-40% solution; however, for dilution, it
should be considered to be 100%.
TRUE
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
TRUE
preservative is prepared in 2
stock solutions and mixed immediately
before use.
MIF (Merthiolate-Iodine-Formaldehyde)
Good stain preservative for most
kinds and stages of parasites
found in feces. But not suitable for some permanent stained smears like trichrome.
MIF
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.
C
[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.
IMEMORIZE MO
TRUE OR FALSE
[MIF]
preserved specimen, if undisturbed
within 24 h, form 3 well-defined layers: upper, interface, bottom
TRUE
[mif]
clear orange fluid, consists
mainly of formalin, merthiolate
and water; it does NOT trap eggs and protozoa
Upper
[mif]
thick, pale orange or
creamy yellow, usually 1-2 mm
thick;
may trap some protozoa
and helminth eggs
interface
[mif]
consists of deeper staining
particulate matter;
eggs and protozoa are found
throughout this layer
bottom
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).
SAF (Sodium Acetate-Acetic Acid-Formalin)
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.
SAF
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
SAF
Components:
Sodium acetate 1.5 g
Acetic acid, glacial 2.0 ml
Formaldehyde,
37-40% solution 4.0 ml
Distilled water 92.0 ml
SAF (Sodium Acetate-Acetic Acid-Formalin)
- Mix equal parts of egg white and
glycerin. - Place 1 drop on microscope slide,
and 1 drop of SAF-preserved fecal
sediment. - After mixing, allow the smear to dry at
room temperature for 30 min prior to
staining
Mayer’s Albumin
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.
WALA LANG IMEMORIZE MO LANG DIN ULIT, OKAY? SIGE JINJJARO (insert sir culliao’s voice)
Provides excellent preservation of
morphology of protozoan
trophozoites and cysts but Inadequate preservation of helminth eggs and larvae, coccidian and microsporidia.
PVA (Polyvinyl Alcohol)
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.
PVA (Polyvinyl Alcohol)
[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.
BEH IMEMORIZE MO NALANG OR FAMILIARIZE WHATEVER PAGOD NAKO :))
TRUE OR FALSE
Stool O and P is a routine laboratory procedure performed for diagnosis of intestinal parasitosis.
TRUE
TRUE OR FALSE
A thumb-sized specimen of formed stool is considered sufficient to
perform routine parasitologic procedures such as O and P.
TRUE
TRUE OR FALSE
Ideally, a single specimen is sufficient to conclude whether or not a patient has intestinal parasitosis.
FALSE
TRUE OR FALSE
With the exception of oil-based ones, cathartics allow higher yield of parasites, hence better diagnosis of parasitosis.
TRUE
Information on the specimen container should match those that are
found in the requisition form during submission of a fecal sample.
TRUE
