Safety Precautions In Handling Biological Specimens Flashcards
Laboratorians working with stool specimens face potential risks including:
ingestion of eggs or cysts
skin penetration by infective larvae
infection by nonparasitic agents found in stool and biologic fluids
risks can be minimized by adopting__________ as well as____________ (Biosafety Level ___)
universal precautions
standard microbiological laboratory practices
2
Wear protective (3) when processing specimens.
safety glasses, gloves, and laboratory coat
Use_______ as needed.
biological safety cabinets
_________ work surface at least once a day and after spill of potentially infectious material.
Decontaminate
If you have cuts or abrasions on the skin on your hands, cover them with
adhesive dressing
_________ and ________ after completing any task involving the handling of fecal material.
Remove gloves and wash your hands
T or F
stool specimens that have been fixed in preservatives because may still be infectious.
True
fixation in_____ takes days or weeks to kill some parasite cysts or oocysts that are protected by a thick shell.
formalin
Eggs of nematodes like:
may continue to develop into the infective stage even when preserved in formalin.
Ascaris lumbricoides
Trichuris trichiura
hookworm
Follow universal precautions for the prevention of bloodborne pathogens when working with human serum and other body fluids. These include:
Wear personal protective equipment such as safety glasses, gloves, and laboratory coats.
If you have cuts or abrasions on the skin of your hands, cover them with adhesive dressing.
Use needles and lancets only once, and dispose of them in a “sharps” container for decontamination.
Remove gloves and wash your hands after completing any task involving the handling of biological material.
is the most commonly used specimen in the diagnosis of parasitic infections.
However:
(5) may also be used for the demonstration of parasites’ diagnostic stages.
Stool specimen
blood, sputum, urine, other body fluids, and tissue biopsy
The usual diagnostic stages of intestinal parasites are protozoan ____ and ____ and, helminth _____ and _____
trophozoites and cysts
eggs and larvae
Since stool is the most commonly used specimen in the laboratory, proper (4) should be done so as to ensure a more accurate and reliable result.
collection
preservation
transportation
processing
Proper_____ and proper______ for collecting materials must be provided to ensure satisfactory specimen for examination.
instructions
containers
The following factors should be considered in collecting fecal specimens:
type of container
Size
age of the specimen
substances that might interfere with examinations
The container should be (3) to accommodate a sample of adequate size.
clean, dry, and sufficiently large
Container should be______, with a tight-fitting lid to prevent spills
leak proof
______ and _____ should be recorded on the container or should accompany the specimen.
Information identifying the patient and the date and hour of passage
Information in identifying the patient
Name
Age
Sex
Ideally, unpreserved specimens should arrive in the laboratory within _____ after passage
1 to 2 hours
To allow adequate macroscopic and microscopic examination, the________ should be submitted to the laboratory.
entire fecal passage
Portion that is preferred for preparing smears for staining
soft and mucoid portion
Portion that are used for concentration.
more formed portions
is often useful in the diagnosis of Shistosoma mansoni and Entamoeba histolytica infections.
Surface material
If the entire fecal specimens cannot be submitted, a quantity of about _____ should be provided to the laboratory.
20-30 grams
if formed (size)
the size of a medium-size walnut
if loose or watery (size or hm)
2-3 tablespoonful
Several substances generally referred to as “________”, will make the specimen unsuitable for parasitologic examinations.
interfering substances
Interfering substances
– will destroy trophozoites
Urine and water
Interfering substances
Feces contaminated with _____ and ____ is not suitable for examination.
soil and pollen
Not only does_____ destroy trophozoites, but there is danger in free-living organisms contaminating the feces and making diagnosis difficult.
water
Certain drugs and compounds will also render the stool specimens unsatisfactory for examination or for detection of organisms. Among these are:
antidiarrheal compounds
Antibiotics
Antacids
Bismuth
Barium
antimalarial agents
Oily laxatives such as mineral oil may also interfere with examination.
– may decrease the number of organisms, especially protozoa, in the intestinal tract for several weeks
antibiotics or contrast media
After barium and bismuth have been given
Specimens should not be collected ___________ since crystals and particles of these compounds in the feces will interfere with examination and may destroy trophozoites by their abrasive action
7 to 10 days
stools should not be collected in patients given gallbladder dye – until about ______ afterwards
3 weeks
Specimens collected in very cold regions should not be allowed to freeze since_______ and _______ – may destroy protozoan cysts and trophozoites
freezing and thawing
Portions of the specimen should be preserved for future examination and for staining. Most laboratories use a ________
two-vial technique
two-vial technique:
one portion of specimen is fixed in three parts of_________ and another portion in three parts of________
5-10% buffered formalin
polyvinyl alcohol (PVA) fixative
MIF
merthiolate-iodine-formalin
SAF
sodium acetate-formalin (SAF)
PVA
Polyvinyl alcohol
Fixatives that contain mercury
Schaudinn’s
PVA fixatives
Does not contain mercury
SAF
the quality of ________ when using SAF is not as good as with Schaudinn’s or PVA fixatives
permanent stains
Best for concentration
Formalin
Best for permanent stain
PVA
The stool specimen should be submitted with the following information:
- patient’s name
- age
- sex
- date/time of collection
- requesting physician
- requested procedure
- presumptive diagnosis
- prior infections
- travel history
- antacids
- anti-diarrheals
- barium
- bismuth
- laxatives
All of these drugs have been found to leave_____ residues that can interfere with the identification of parasites. Stool samples should be collected _____ after the last intake of any of these drugs
crystalline
week
Intake of_____ usually decreases the number of protozoans for several weeks.
antibiotics
Contamination with toilet water, urine, or soil must be prevented since these can destroy__________.
In addition, soil and water may contain free-living organisms that would complicate diagnosis of infections.
protozoan trophozoites
Age of the stool sample is very important for diarrheic specimens since the trophozoites it may contain are likely to die within____________ after passage. Therefore, stools must be examined within that period of time.
30 minutes to 1 hour
Delay in examination of specimens may require______ to ensure that parasites are present in the identifiable stage.
preservation
Temporary storage of fecal samples in a refrigerator______ is acceptable, but prolonged refrigeration can bring about desiccation.
_______are killed by refrigeration, although______&_____ are usually not damaged.
(3-5°C)
Trophozoites
helminth eggs and protozoan cysts
NEVER ______ STOOL SAMPLES.
NEVER KEEP THEM IN______.
F R E E Z E
INCUBATORS
