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Questions and Answers
What is the primary disadvantage of using permanent stains in preserving protozoa morphology?
What is the primary disadvantage of using permanent stains in preserving protozoa morphology?
- The preparation process is difficult
- The shelf life is short
- It does not preserve parasite morphology adequately (correct)
- It is expensive
What is the alternative to mercury-based PVA in modified PVA?
What is the alternative to mercury-based PVA in modified PVA?
- Schaundinn's solution
- Both a and b (correct)
- Zinc sulfate
- Copper sulfate
What is the advantage of using Schaundinn's fixative?
What is the advantage of using Schaundinn's fixative?
- It is suitable for concentration methods
- It is less expensive than PVA
- It is easy to prepare and preserves morphology of protozoan trophozoite and cysts (correct)
- It does not contain mercuric chloride
What is the primary advantage of using mercury-containing preservatives?
What is the primary advantage of using mercury-containing preservatives?
Which of the following is a limitation of direct wet preparation for the examination of O&P?
Which of the following is a limitation of direct wet preparation for the examination of O&P?
What is the limitation of using trophozoites in permanent stained smears?
What is the limitation of using trophozoites in permanent stained smears?
What is the primary disadvantage of using PVA in preparing slides for staining?
What is the primary disadvantage of using PVA in preparing slides for staining?
Which of the following stool colors is associated with upper GI bleeding?
Which of the following stool colors is associated with upper GI bleeding?
What is the purpose of adding iodine to a stool specimen in direct wet preparation?
What is the purpose of adding iodine to a stool specimen in direct wet preparation?
What is the advantage of using modified PVA in concentration methods?
What is the advantage of using modified PVA in concentration methods?
Which of the following is NOT a type of direct wet preparation?
Which of the following is NOT a type of direct wet preparation?
What is the primary disadvantage of using Schaundinn's fixative?
What is the primary disadvantage of using Schaundinn's fixative?
What is a possible cause of a pale yellow-colored stool?
What is a possible cause of a pale yellow-colored stool?
Which of the following organisms can be detected using direct wet preparation?
Which of the following organisms can be detected using direct wet preparation?
What is a characteristic of direct wet preparation using saline?
What is a characteristic of direct wet preparation using saline?
Which of the following is NOT a possible cause of a red-colored stool?
Which of the following is NOT a possible cause of a red-colored stool?
What is the primary advantage of using the Direct Saline Wet Preparation technique?
What is the primary advantage of using the Direct Saline Wet Preparation technique?
What is the purpose of using a 22-mm square coverslip in the Direct Saline Wet Preparation?
What is the purpose of using a 22-mm square coverslip in the Direct Saline Wet Preparation?
What is the primary reason why parasitic diseases are prevalent in underdeveloped tropical and subtropical countries?
What is the primary reason why parasitic diseases are prevalent in underdeveloped tropical and subtropical countries?
What is the main difference between the Direct Saline Wet Preparation and the Zinc Sulfate Flotation Technique?
What is the main difference between the Direct Saline Wet Preparation and the Zinc Sulfate Flotation Technique?
What is the effect of iodine on trophozoites in the Direct Iodine Preparation?
What is the effect of iodine on trophozoites in the Direct Iodine Preparation?
What is the recommended duration before or after taking a drug that interferes with sample collection?
What is the recommended duration before or after taking a drug that interferes with sample collection?
What is the primary advantage of using the Zinc Sulfate Flotation Technique?
What is the primary advantage of using the Zinc Sulfate Flotation Technique?
What is the minimum acceptable amount of stool required for analysis?
What is the minimum acceptable amount of stool required for analysis?
Why is it important to avoid collecting stool samples from the toilet bowl?
Why is it important to avoid collecting stool samples from the toilet bowl?
What is the main disadvantage of using the Direct Saline Wet Preparation technique?
What is the main disadvantage of using the Direct Saline Wet Preparation technique?
What is the purpose of using Lugol's Iodine or D'Antoni's formula in the Direct Iodine Preparation?
What is the purpose of using Lugol's Iodine or D'Antoni's formula in the Direct Iodine Preparation?
What is the main reason why water should not be used to collect stool samples?
What is the main reason why water should not be used to collect stool samples?
What is the recommended duration after antibiotic or anti-malarial therapy before collecting stool samples?
What is the recommended duration after antibiotic or anti-malarial therapy before collecting stool samples?
What is the main difference between the Direct Iodine Preparation and the Zinc Sulfate Flotation Technique?
What is the main difference between the Direct Iodine Preparation and the Zinc Sulfate Flotation Technique?
What is the primary purpose of the three phases of laboratory analysis in parasitic disease diagnosis?
What is the primary purpose of the three phases of laboratory analysis in parasitic disease diagnosis?
Why is it important for clinicians to have knowledge of the clinical manifestation of parasitic diseases?
Why is it important for clinicians to have knowledge of the clinical manifestation of parasitic diseases?
What is the principle of the Formalin-Ethyl Acetate Sedimentation Procedure?
What is the principle of the Formalin-Ethyl Acetate Sedimentation Procedure?
What is the main advantage of the Trichrome stain?
What is the main advantage of the Trichrome stain?
What is the purpose of reviewing 300 fields under the microscope?
What is the purpose of reviewing 300 fields under the microscope?
What is the main difference between sedimentation and flotation techniques?
What is the main difference between sedimentation and flotation techniques?
What is the primary use of the Acid Fast stain?
What is the primary use of the Acid Fast stain?
What is the advantage of using stool screening methods?
What is the advantage of using stool screening methods?
What is the purpose of using a commercial antibody in stool screening methods?
What is the purpose of using a commercial antibody in stool screening methods?
What is the main difference between Iron Hematoxylin and Modified Iron Hematoxylin stains?
What is the main difference between Iron Hematoxylin and Modified Iron Hematoxylin stains?
Study Notes
Laboratory Techniques for Parasitology
- Direct Saline Wet Preparation:
- Made by mixing a drop of 0.85% saline with a small portion of unfixed stool on a glass slide
- Advantage: good recovery of most parasites and easy to perform
- Disadvantage: contains more fecal debris than floatation techniques, making it challenging for microscopists
- Direct Iodine Wet Preparation:
- Uses a single drop of Lugol's Iodine or D'Antoni's formula instead of saline
- Enhances detail of protozoan cysts (glycogen and nuclei) and kills trophozoites present
- Zinc Sulfate Flotation Technique:
- Based on differences in specific gravity, where parasites float on top and debris sinks to the bottom
- Advantage: removes more fecal debris, yielding a cleaner preparation for microscopic examination
- Disadvantage: some helminth eggs are dense and will not float
Clinical Parasitology
- Introduction:
- Parasitic diseases are a significant threat globally, prevalent in underdeveloped tropical and subtropical countries
- Climate conditions, poor sanitation, and personal hygiene practices contribute to the spread of parasitic diseases
- Importance of Laboratory Testing:
- Critical for clinicians to understand laboratory tests and clinical manifestations of parasitic diseases
- Successful laboratory identification of parasites requires knowledge and practice of laboratory testing in three phases
Stool Collection and Handling
- Stool Specimen:
- Must be collected in a clean, tight container with a tight-fitting lid
- Acceptable amount: 2.5 grams (walnut or pea size)
- Must not be contaminated with urine, as it can destroy parasites
- Interfering Elements:
- Barium, bismuth, and mineral oil can interfere with laboratory tests
- Samples from patients taking these medications must be collected 5-7 days before or after treatment
Permanent Stains
- Advantages:
- Easy to prepare
- Preserves specimen for several years
- Has long shelf life
- Disadvantages:
- Does not preserve parasite morphology adequately
- Trophozoites can't be recovered, and morphologic details of cysts and eggs may fade with time
Concentration Techniques
- Formalin-Ethyl Acetate Sedimentation Procedure:
- Most widely used sedimentation technique
- Principle: parasites are heavier than the solution and settle in the sediment of the tube
- Zinc Sulfate Flotation Technique:
- Based on differences in specific gravity, where parasites float on top and debris sinks to the bottom
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Description
This quiz covers the advantages and disadvantages of preserving protozoa morphology using permanent stains and mercury-containing preservatives. Learn about the benefits and drawbacks of different preservation methods.
