FECT Flashcards
ADVANTAGES of CONCENTRATION TECHNIQUE
Maximizes the number of organisms detected which may be too scanty to be seen by direct microscopy alone.
Separate parasites from fecal debris
DISADVANTAGES of CONCENTRATION TECHNIQUE
Destroys trophozoite stages
Distorts any cellular components
ADVANTAGES of SEDIMENTATION TECHNIQUE
Recovers most ova, cysts, and larvae.
Morphology of most parasites is retained.
Less risk of infection from bacteria and viruses.
DISADVANTAGES of SEDIMENTATION TECHNIQUE
Preparation contains debris.
Some parasites do not concentrate well.
Ether is flammable and formalin is an irritant.
Liquid feces do not concentrate well.
ADVANTAGES of FLOATATION TECHNIQUE
The concentrate is clear of debris
DISADVANTAGES of FLOATATION TECHNIQUE
Delay in examination can result in distortion
Larvae and some fluke eggs do not concentrate
Frequent checking of specific gravity
2 Sedimentation techniques
Acid Ether Concentration Technique + 40% HCI
Formalin Ether/Ethyl Acetate Concentration Technique
4 Concentration techniques
Brine Floatation (NSs)
Zinc Sulfate Floatation
Sheather’s Sugar Floatation
McMaster Technique
A procedure that allow for the detection of parasitic elements (eggs, larvae, oocysts and cysts) that may be missed when examining only a direct wet preparation
FECT
FECT
A procedure that allow for the detection of parasitic elements (ELOC) that may be missed when examining only a direct wet preparation
eggs
larvae
oocysts
cysts
This technique is not recommended for eggs of_______ and larvae of______
Fasciola spp.
Strongyloides stercoralis
FECT
Examples of parasitic stages that might be seen under the microscope
Faciola egg
Entamoeba cysts.
Ancylostoma Egg.
Bacterial rods
Isospora oocyst
Isospora canis (coccidia) oocysts
Coccidia
_________ in General
Are techniques used to separate parasites from fecal debris and increase the chances of detecting parasitic organisms when these are in small numbers.
Concentration Techniques
2 types of conc. techniques
Sedimentation technique
Floatation/Flotation technique
Floatation techniques (3)
Saturated saline
Zinc sulfate
Sheather’s sugar
Sedimentation techniques
Saline
Formol ether
Use solutions of lower specific gravity than the parasitic organisms, thus concentrating the latter in the sediment.
Sedimentation technique
are recommended for general diagnostic laboratories because they are easier to perform and less prone to technical errors.
Sedimentation techniques
_____ is the sedimentation technique used at CDC of USA and is recommended by the WHO
FECT
Floatation Techniques
Most frequently used:
zinc sulfate
Sheather’s sugar
Floatation techniques
Use solutions which have _________ sg than the organisms to be floated so that the organisms rise to the top and the debris sinks to the bottom together with the solution, since mas mabigat sila essentially.
higher specific gravity
The main advantage of this technique is to produce a cleaner material than the sedimentation technique.
Floatation technique
The disadvantages of most floatation techniques are that the walls of____ and ____ will often collapse, thus hindering identification.
Also, some parasite eggs do not float
eggs and cysts
is a widely used sedimentation technique for the diagnosis of intestinal protozoa in preserved stool samples
The formalin-ether concentration technique (FECT)
The most commonly used fixatives for stool preservation are either ______ or _______
formalin
sodium acetate-acetic acid-formalin (SAF)
The use of________ instead of_____ avoids the flammability problem of ____, and EA can be used with specimens preserved in formalin, MIF or SAF.
ethyl acetate
ether
can be used with specimens preserved in formalin, MIF or SAF.
Ethyl acetate
FECT lacks sensitivity for the diagnosis of________
helminths
Its diagnostic accuracy is inferior to that of the widely used Kato-Katz technique for the diagnosis of:
Schistosoma mansoni
Common soil-transmitted helminths
(A. lumbricoides, T. trichiura, and hookworm)
______ conical centrifuge tube
15 mL
4 layers after final centrifugation
Top layer of ethyl acetate/ether/
A plug of fatty debris that is adherent to the wall of the tube
A layer of formalin
The sediment ( which should contain the parasite in search of)
What can we detect using Sedimentation
•Heavy eggs (Ascaris egg)
• Operculated eggs (Trematodes)
• Larvae (Strong stercolaris.)
• Cysts
What can we detect using Floatation
• Non Operculated eggs
Trematodes (Schistosoma.)
Cestode
Nematode (Hookworms)
• Cysts
Less distortion of cysts occurs with this technique than with zinc sulfate method and it is more effective in concentrating formalinized specimens.
FECT
______ eggs may be missed, however, and concentration of_____ cysts and____ cysts may not be very good.
Hymenolepis nana
Giardia lamblia
iodamoeba butschlii
Ether, ethyl acetate or, if these solvents are unavailable,________.
gasoline
is highly volatile and will ignite and explode quickly if there is an open flame or spark nearby.
Ether
FECT
This procedure makes use of 10% formalin which is an_______, and ether, which can______ in the stool.
all purpose fixative
dissolve neutral fats
FECT
This is useful in the recovery of both
helminth eggs
protozoan cysts
FECT can also be done with______ stools
More parasites can be recovered from formalin preserved samples.
Parasite morphology is also better preserved in formalin than in PVA.
Sediments from FECT can be stored for a long period of time.
formalin-preserved and PVA-preserved stools.
Those who have tried ethyl acetate claim that it is more efficient than ether in the recovery of______ and _____
However, ethyl acetate is not as efficient as ether in the extraction of____ or _____ from the stool.
cestode eggs and Giardia cysts
fat or mucoidal material
Formalin is an all purpose fixative.
A_____ concentration is recommended for protozoan cysts, while a ____concentration is recommended for helminth eggs and larvae.
5%
10%
Formalin solution may be buffered with_______ to preserve the morphological characteristics of the organisms.
Preserved stool can be concentrated using___________
sodium phosphate
formalin-ether/ ethyl acetate concentration technique (FECT)
