MCQ on Laboratory diagnosis - specimen collection, culture methods and identification (Medical microbiology)

 

         MCQ on Laboratory diagnosis of the diseases caused by bacteria, fungi, and viruses

1) Select all the important procedures that are required when performing the routine collection method of microbial specimens

a. A specimen should be collected in a sterile container

b. A specimen should be properly labeled with the patient's name, date, and time of collection

c. A specimen should be collected by using a sterile cotton swab or collection needles 

d. A specimen should be collected only after the start of antibiotic therapy 

2) Which of the following is the correct volume size of blood specimen taken from the adult patient for the routine laboratory diagnosis of the infection and the identification of the possible pathogen?

a. 1 ml

b. 10 ml     

c. 20 ml

d. 0.5 ml

3) Which of the following specimens are appropriate clinical specimens and are commonly used for the proper diagnosis of Salmonellosis? 

Select all the correct options

a. Blood specimen     

b. Throat swab

c. Urine specimen

d. Stool specimen     

4) Which of the following specimen collection procedure can give accurate results for the laboratory diagnosis of Tuberculosis?

a. Throat swab specimen each morning for 3 consecutive days

b. Sputum specimen each morning for 3 consecutive days      

c. Blood specimens once a week for 2 weeks

d. Skin biopsy test before the start of antibiotics therapy

5) Name the routine method used for the direct microscopic examination of a urine sample taken from a person suspected of urinary tract infection?

a. Wet mount method

b. Hanging drop method

c. Thin and thick smear method

d. Widal test method

6) Herpes simplex virus is one of the contagious viral diseases, HSV 1 is can spread from person to person. 

Which of the following cells appear as multinucleated cells taken from the lesion specimen and can be observed by the direct microscopy method?

a. 

b. Buruli ulcer cells

c. Schizont cells

d. Tzanck cells     

7) Which of the following temperature can be optimal for the storage of swab specimens taken from the Coronavirus infected patient while performing the Covid-19 test method? 

a. 2 to 4 degrees Celsius for up to 24 hours after the specimen collection

b. 25 degrees celsius for up to 3 days after the specimen collection

c. 2 to 4 degrees Celsius for up to 72 hours after the specimen collection     

d. 5 to 10 degrees Celsius for up to a week after the specimen collection

8) Which of the following microorganism can be detected by their ability to produce a toxin and can be identified by Elek's test method?

a. Cryptococcus neoformans

b. Corynebacterium diphtheria     

c. Mycobacterium tuberculosis

d. Bacillus anthracis

9) Which of the following chemical compound is commonly used to clean and decontaminate the infected skin area or nail before the collection of the specimens and laboratory diagnosis?

a. Iodine solution

b. KOH solution

c. Warm water

d. 70% alcohol     

10) Which of the following is the most widely used test for the detection of genetic material in the Covid-19 swab sample?

a. PCR test (Polymerase chain reaction)      

b. Western blot test

c. ELISA (Enzyme-linked immunosorbent assay)

d. Animal inoculation test

11) Which of the following specimen is appropriate for the laboratory diagnosis of meningitis?

a. Throat swab

b. Hair and skin samples

c. Cerebrospinal fluid

d. Urine specimen

12) Direct microscopy is a common laboratory diagnosis procedure performed for the detection of spores or mycelia present in fungi. 

Select all the correct methods or steps for the procedure

a. 1- 2 drops of potassium hydroxide are added to the slide that contains the specimen (skin, hair, or sputum) 

b. The slide is covered with the coverslip

c. The slide is kept in the refrigerator for 15 minutes to digest the keratin present in a specimen

d. The slide is observed under the microscope

13) Name all the common types of cell culture methods most frequently used in the isolation of a virus

a. Animal inoculation

b. Tissue culture

c. Embryonated eggs

d. Agar culture media

14) A blood smear is considered the gold standard diagnosis for identification of malarial parasite.

Name the commonly used stain for the identification of the material parasite and detection of the life stages of the parasite?

a. Lactophenol cotton blue

b. Giemsa stain

c. Gram stain

d. Malachite green 

15) Select all the important laboratory techniques and methods used for the identification of different microorganisms

a. Microscopic methods

b. Culture methods

c. Serological methods

d. Animal inoculation

e. Antigen detection test

f. Molecular methods

16) What is the ideal time period limit for the transportation of the specimen to the laboratory after the collection method?

a) 2 minutes

b) 30 minutes

c) 1 hour

d) 2 hours

17) Which of the following preservatives is commonly used to preserve urine specimen?

a. Boric acid

b. Ethyl alcohol

c. Formalin

d. Hydrogen peroxide

18) Which of the following anticoagulant is used for the preservation of blood and bone marrow specimens?

a. Boric acid

b. Ethyl alcohol

c. Polyvinyl alcohol

d. Sodium polyanethol sulfonate (SPS)

19) What is the correct standard method used by a microbiologist for the storage of specimens such as urine, stool and swabs?

a. Storage at frozen -80 degree Celsius

b. Storage at refrigerator at 4 degree Celsius

c. Storage at room temperature at 25 degree Celsius

d. None of the above

20) Which of the following is the appropriate oxygen and carbon dioxide levels for the incubation and culture of capnophilic bacteria such as Haemophilus influenzae and Neisseria gonorrhoeae?

a. 0.03% CO2 and 21% O2 

b. 5% to 10% CO2 and 0% O2

c. 5% to 10% CO2 and15% O2

d. 0.03% CO2 and 0% O2 

21) Gram stain also known as differential stain is the principle stain mainly used in the microscopic identification and differentiation of which of the following group of pathogens?

a) Gram positive and gram negative bacteria

b) Mold, yeast and Fungi

c) DNA and RNA Viruses

d) Helminths and protozoa 

22) All of the following are macroscopic morphology in culture/agar media that should be observed by a microbiologist in the identification process of the bacteria, Except

a. Colony shape and size

b. Pigmentation of the colony

c. Surface appearance of the colony

d. Microscopic observation of the colony

Answers:

1) a., b., and c

2) 10 ml

3) a. Blood specimen and d. Stool specimen

4) Sputum specimen each morning for 3 consecutive days

5) Wet mount method

6) d. Tzanck cells

7) c. 2 to 4 degrees Celsius for up to 72 hours after the specimen collection 

8) b. Corynebacterium diptheriae

9) d. 70% alcohol

10) a. PCR test

11) c. Cerebrospinal fluid

12) a., b., and d. are the correct answers. 

The option c) is incorrect, the slide should be heated gently over the flame to digest the keratin

13) a., b., and c. are the correct answers. 

The option d) is incorrect, because virus cultivation is very difficult in artificial culture media (solid agar culture media) 

14) b. Giemsa stain

15) All of the options, a) to f)

16) d. 2 hours

17) a. Boric acid

18) d. Sodium polyanethol sulfonate (SPS), it is added in collection tubes or vials to prevent clotting of blood specimens.

19) b. Storage at refrigerator at 4 degree Celsius

20) c. 5% to 10% CO2 and15% O2 

21) a. Gram positive and gram negative bacteria

22) a. Colony shape and size, b. Pigmentation of the colony and c. Surface appearance of the colony