Ziehl-Neelsen Staining 50 FAQs and 30 MCQs
Ziehl-Neelsen Staining 50 FAQs
What is the Ziehl-Neelsen stain?
It is a bacteriological staining technique used to identify acid-fast bacteria under microscopy.
What is the purpose of the Modified Ziehl-Neelsen stain?
To detect acid-fast bacilli in clinical specimens.
Who is responsible for performing the Modified Ziehl-Neelsen staining?
Laboratory technicians.
Who oversees the implementation of the SOP for Ziehl-Neelsen staining?
The laboratory supervisor/manager.
What is the role of the Quality Assurance Officer in this process?
To monitor and evaluate quality control measures.
What are acid-fast bacteria?
Bacteria that retain stain despite decolorization by weak acids, typically due to a waxy cell wall.
Why can’t Mycobacterium species be stained by simple stains?
Their cell walls contain mycolic acid, making them impervious to aqueous staining solutions.
What is the significance of acid-fast staining in diagnosing tuberculosis?
It helps identify Mycobacterium tuberculosis in sputum samples.
What are the two types of acid-fast staining methods?
Hot method (Ziehl-Neelsen) and cold method.
Who introduced acid-fast staining?
Ehrlich in 1882.
What PPE should be worn during Ziehl-Neelsen staining?
Gloves, laboratory coat, and safety goggles.
Why is proper ventilation important during staining?
To minimize exposure to fumes from staining solutions.
How should carbol fuchsin and acid-alcohol decolorizer be handled?
With caution, as they may cause irritation and staining.
What should be done with waste materials after staining?
Dispose of them according to laboratory safety protocols.
What is the risk of overheating slides during heat fixation?
It may distort the morphology of the bacilli.
What are the primary reagents used in Ziehl-Neelsen staining?
Carbol fuchsin, acid-alcohol decolorizer, and methylene blue counterstain.
What equipment is needed for heat fixation?
Bunsen burner or alcohol burner.
What is the purpose of a staining rack?
To hold slides during the staining process.
Why are positive and negative control slides used?
To ensure the reliability of staining results.
What is the role of immersion oil in microscopic examination?
To enhance resolution under the 100x objective lens.
How is a heat-fixed smear prepared?
By passing the slide through a flame several times to fix the specimen.
What is the purpose of heating the carbol fuchsin solution?
To soften the waxy material on the bacterial cell wall.
How long should the carbol fuchsin be heated?
Until steam rises, but not boiling, for about 5 minutes.
What is the purpose of decolorization with acid-alcohol?
To remove the stain from non-acid-fast organisms.
How long should the decolorization process take?
Approximately 15-20 seconds.
What is the role of methylene blue in the staining process?
To counterstain non-acid-fast organisms and the background.
How long should the counterstain be left on the slide?
1-2 minutes.
What should be done if the smear is not properly decolorized?
Repeat the decolorization process.
How should the slide be dried after staining?
Gently blot with bibulous paper or allow it to air-dry.
What magnification is used for microscopic examination?
1000x under oil immersion.
What do acid-fast bacilli look like under the microscope?
Bright red against a blue background.
What do non-acid-fast organisms look like?
Blue.
What should be recorded during microscopic examination?
Observations and any abnormalities detected.
How should staining results be documented?
In a laboratory notebook or electronic record, including dates and procedures.
Where should stained slides be stored?
In slide boxes or folders for future reference.
Why are control slides used in each staining batch?
To ensure the reliability of results.
How often should staining reagents be checked for contamination?
Regularly, with stains filtered at least weekly.
How many slides should be stained per batch?
Twelve, including two control slides.
What should be done if staining reagents show signs of deterioration?
Replace them immediately.
Why is it important to clean the 100x lens before and after use?
To prevent false-positive results from debris.
What is the main application of Ziehl-Neelsen staining?
Diagnosing pulmonary tuberculosis.
What type of sample is used for tuberculosis diagnosis?
Sputum
What does a positive result for acid-fast bacilli indicate?
The presence of Mycobacterium tuberculosis or other acid-fast bacteria.
What is the significance of mycolic acid in Mycobacterium species?
It makes the cell wall impervious to aqueous staining solutions.
Why is Ziehl-Neelsen staining considered a differential staining method?
It differentiates acid-fast bacteria from non-acid-fast organisms.
What should be done if the smear is not uniformly stained?
Ensure proper heat fixation and even application of reagents.
What causes false-positive results in Ziehl-Neelsen staining?
Contaminated reagents or debris on the lens.
How can overheating during heat fixation be avoided?
Pass the slide through the flame quickly and avoid prolonged heating.
What should be done if the counterstain appears too dark?
Reduce the counterstaining time or dilute the methylene blue solution.
How can staining quality be consistently maintained?
By following SOPs, using control slides, and regularly monitoring reagents.
Ziehl-Neelsen Staining 30 MCQs
- What is the primary purpose of the Ziehl-Neelsen stain?
a) To identify Gram-positive bacteria
b) To detect acid-fast bacilli✔
c) To stain fungal hyphae
d) To differentiate viruses - Which bacteria are primarily identified using Ziehl-Neelsen staining?
a) Escherichia coli
b) Mycobacterium tuberculosis ✔
c) Staphylococcus aureus
d) Streptococcus pneumoniae - What makes Mycobacterium species resistant to simple staining methods?
a) Lack of a cell wall
b) Presence of mycolic acid in the cell wall ✔
c) High water content
d) Presence of flagella - Who introduced the acid-fast staining technique?
a) Louis Pasteur
b) Robert Koch
c) Paul Ehrlich ✔
d) Alexander Fleming - What type of staining method is Ziehl-Neelsen staining?
a) Simple staining
b) Differential staining ✔
c) Negative staining
d) Fluorescent staining
- Which PPE is essential during Ziehl-Neelsen staining?
a) Gloves and lab coat
b) Safety goggles and gloves
c) Lab coat, gloves, and safety goggles ✔
d) Only a lab coat - Why is proper ventilation important during staining?
a) To prevent bacterial contamination
b) To minimize exposure to staining fumes ✔
c) To maintain slide temperature
d) To avoid staining errors - What should be done with waste materials after staining?
a) Dispose of them in regular trash
b) Follow laboratory safety protocols✔
c) Reuse them for future staining
d) Burn them immediately
- Which reagent is used as the primary stain in Ziehl-Neelsen staining?
a) Methylene blue
b) Carbol fuchsin ✔
c) Acid-alcohol
d) Gram’s iodine - What is the purpose of acid-alcohol in Ziehl-Neelsen staining?
a) To fix the smear
b) To decolorize non-acid-fast organisms✔
c) To counterstain the background
d) To heat the slide - Which equipment is used for heat fixation?
a) Microscope
b) Bunsen burner ✔
c) Staining rack
d) Centrifuge - What is the role of immersion oil in microscopic examination?
a) To clean the slide
b) To enhance resolution under the 100x objective ✔
c) To fix the smear
d) To decolorize the slide
- How long should the carbol fuchsin be heated during staining?
a) 1 minute
b) 5 minutes ✔
c) 10 minutes
d) 15 minutes - What is the purpose of heating the carbol fuchsin solution?
a) To kill the bacteria
b) To soften the waxy cell wall of Mycobacterium ✔
c) To fix the smear
d) To enhance the color of the stain - What is the decolorizing agent used in Ziehl-Neelsen staining?
a) 20% H2SO4 ✔
b) 95% ethanol
c) Methylene blue
d) Gram’s iodine - How long should the decolorization process take?
a) 5-10 seconds
b) 15-20 seconds ✔
c) 1-2 minutes
d) 5 minutes - What is the counterstain used in Ziehl-Neelsen staining?
a) Carbol fuchsin
b) Acid-alcohol
c) Methylene blue✔
d) Gram’s iodine - How long should the counterstain be left on the slide?
a) 30 seconds
b) 1-2 minutes✔
c) 5 minutes
d) 10 minutes
- What color do acid-fast bacilli appear under the microscope?
a) Blue
b) Green
c) Pink/red✔
d) Purple - What color do non-acid-fast organisms appear under the microscope?
a) Blue✔
b) Pink
c) Green
d) Purple - What magnification is used for microscopic examination?
a) 40x
b) 100x
c) 400x
d) 1000x✔ - What should be recorded during microscopic examination?
a) Only positive results
b) Observations and abnormalities ✔
c) Only negative results
d) The time taken for staining
- Why are control slides used in each staining batch?
a) To save time
b) To ensure the reliability of results✔
c) To reduce reagent usage
d) To increase staining speed - How often should staining reagents be filtered?
a) Daily
b) Weekly✔
c) Monthly
d) Yearly - What is the maximum number of slides that should be stained per batch?
a) 5
b) 10
c) 12✔
d) 20
- What is the main application of Ziehl-Neelsen staining?
a) Diagnosing viral infections
b) Detecting fungal infections
c) Diagnosing pulmonary tuberculosis✔
d) Identifying Gram-negative bacteria - Which sample is commonly used for tuberculosis diagnosis?
a) Blood
b) Urine
c) Sputum✔
d) Stool - What does a positive result for acid-fast bacilli indicate?
a) Presence of Mycobacterium tuberculosis✔
b) Presence of Escherichia coli
c) Presence of Staphylococcus aureus
d) Presence of Candida albicans
- What causes false-positive results in Ziehl-Neelsen staining?
a) Overheating the slide
b) Contaminated reagents or debris on the lens✔
c) Using too much counterstain
d) Insufficient decolorization - How can staining quality be consistently maintained?
a) By skipping control slides
b) By following SOPs and using control slides✔
c) By reducing staining time
d) By reusing reagents
Possible References Used
