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Questions and Answers
What are the three (3) specimen collection protocols for parasitic infections?
What are the three (3) specimen collection protocols for parasitic infections?
One every other day for 10 days, Six specimens in 14 days, and a quantity of 5-6 tablespoons if the stool is watery.
Which of these options are NOT used as stool preservatives?
Which of these options are NOT used as stool preservatives?
When performing a Direct Fecal Smear, which of these methods are used to detect trophic forms of amoeba and flagellates?
When performing a Direct Fecal Smear, which of these methods are used to detect trophic forms of amoeba and flagellates?
Which of the following is the best fixative for Coccidian oocysts?
Which of the following is the best fixative for Coccidian oocysts?
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What is the purpose of Concentration Techniques?
What is the purpose of Concentration Techniques?
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Which of the following methods are used to assess the intensity of helminth infections?
Which of the following methods are used to assess the intensity of helminth infections?
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The primary goal of a microscopic examination is to identify only adult worms or worm segments.
The primary goal of a microscopic examination is to identify only adult worms or worm segments.
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What is the main instrument used in a diagnostic parasitology laboratory?
What is the main instrument used in a diagnostic parasitology laboratory?
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Which of these methods are used to assess the quality of reagents?
Which of these methods are used to assess the quality of reagents?
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Briefly explain the significance of a Quality Assessment Program (QAP).
Briefly explain the significance of a Quality Assessment Program (QAP).
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Study Notes
Specimen Collection, Transport, Preservation, and Processing
- Diagnosis of parasitic infections involves identifying parasites or their components and detecting host immune responses.
- Stool is the most common specimen for examination, but other specimens like urine, blood, CSF, sputum, and tissue samples may also be used.
- Stool specimens should be collected in clean, wide-mouthed containers with tight-fitting lids.
- For parasitic infections, stool samples should be taken every other day for 10 days, or 6 specimens within 14 days for amoebiasis
- Samples should include patient name, age, gender, date and time of collection, requested physician, procedure, presumptive diagnosis, prior infections, and travel history.
Factors to Consider for Stool Exam
- Patient's drug/medication intake (e.g., antacids, anti-diarrheals, antibiotics, antimalarials) should be noted.
- Contamination with toilet water, urine, and soil should be avoided.
- The age of stool samples affects the examination results.
- Delays in examination necessitate preservation methods.
- Stool samples should be stored at 3-5°C (refrigerator) and never frozen.
Stool Preservation
- Preservatives (e.g., formalin) prevent helminth egg and larva destruction and preserve protozoan morphology.
- The ratio of stool to preservative is 1:3.
Formalin
- Formalin, in 5% and 10% concentrations, is a common fixative.
- 5% formalin is used for protozoan cysts; 10% formalin is used for helminth eggs and larvae.
Schaudinn's Solution
- Used to preserve fresh stool for staining smears.
- Contains Mercuric Chloride (toxic).
Merthiolate-Iodine Formalin
- Contains Merthiolate/iodine solutions that stain and preserve protozoans.
Polyvinyl Alcohol
- Adheres stool to slides and preserves protozoan cysts/trophozoites for staining.
Sodium Acetate-Acetic Acid Formalin
- A liquid fixative with long shelf-life that does not contain Mercuric chloride.
Macroscopic Examination
- This involves examining the stool's color and consistency.
- Stool consistency can be liquid/soft or formed, which indicates trophozoites or cysts, respectively.
- Different stool colors correspond to different GI bleeding locations.
Microscopic Examination
- White blood cells (WBCs), red blood cells (RBCs), macrophages, Charcot-Leyden crystals, and arthropods eggs are examined.
- Parasites are identified through microscopic examination.
Parasitic Techniques
- Direct fecal smear (unstained and iodine-stained): Detects trophic forms of amoeba and flagellates.
- Kato thick smear: Detects eggs with thick shells, useful for mass stool examinations.
- Concentration Techniques (e.g., sedimentation, flotation): Recover cysts, oocysts, helminth eggs, and larvae.
- Sedimentation: Based on differences in specific gravity
- Flotation: Based on differences in specific gravity.
- Culture Methods: Used for hookworms, Strongyloides, and Trichostrongylus spp.; also for intestinal protozoans; Copro and Harada Mori.
- Egg Counting Procedures: Assess the severity of disease and worm burden.
- Permanent Stains: Identify intestinal protozoans (e.g., B. coli, G. intestinalis).
Other Specimens and Techniques
- Other specimens include blood, CSF, tissue aspirates/biopsies, sputum, and genital secretions.
- Methods to examine such specimens also include thick and thin smears, knott's concentration, and serological testing.
Quality Assurance in the Parasitological Laboratory
- A system for continuous improvement in the reliability, efficiency, and utilization of laboratory services.
- Internal Quality Control (IQC): Internal process review.
- External Quality Assessment (EQA) assessment by an outside party.
- Includes proficiency testing, rechecking/retesting, and on-site evaluations.
- Components include laboratory personnel proficiency, standardized techniques, correct sample collection/processing, proper results analysis, and accurate report writing.
- Quality Assessment Program (QAP): a clinical laboratory requirement for license renewal, including Internal and External Quality Assessment.
Procedure Manual
- Includes instructions for proper specimen collection, reagent/solution preparation, techniques, quality control, reporting, and safety precautions.
- Necessary equipment (e.g., microscope, centrifuge, incubators) and reagents (e.g., stains, fixatives) are also mentioned.
Proper Use of Microscopes
- Understand microscopy parts (head, base, arm, eyepiece, eyepiece tube, objective lens, nose piece, stage, stage clips, aperture, adjustment knobs, microscopic illuminator, condenser, diaphragm) and their functions.
- Instructions for daily microscope maintenance are included (e.g., checking for damage, cleaning, covering).
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Description
This quiz covers the essentials of specimen collection, transport, preservation, and processing for diagnosing parasitic infections. It focuses on the methods for collecting stool and other specimen types while considering factors important for accurate examination. Key information on sample preparation and patient history is also included.
