MCQs on bacterial and fungal culture media: Medical microbiology, Pathology

                                  MCQs on bacterial and fungal culture media

1. Select all the important categories of media that can be used in the laboratory diagnosis of the bacteria?

a) Enrichment media

b) Selective media

c) Differential media

d) Otitis media    

2. Which of the following media (agar or broth) is a commonly used general nutritive rich growth media for gram positive and gram negative bacteria, fungi and yeasts?

a) Brain Heart Infusion (BHI) media      

b) MacConkey agar 

c) Columbia colistin nalidixic acid (CNA) agar

d) Chocolate agar 

3. All of the following are the important constituents of sheep blood agar (BA) medium used for the growth of numerous gram positive and gram negative bacteria, Except

a) 5% sheep blood

b) Sodium chloride (NaCl)

c) Protein source (tryptones)

d) Phenylethyl alcohol

4.  The standard and common sterilization requirement is 121°C and 15 minutes for both culture broth media and agar media before using it for the cultivation and isolation of microorganisms. 

What is the appropriate temperature for molten agar before being poured to petri plates?

a) 25°C 

b) 50°C 

c) 100°C 

b) 121°C  

5. Which of the following selective agar medium is used for the cultivation and isolation of fungal pathogens that cause dermatophytosis?

a) Chocolate agar

b) MacConkey agar

c) Nutrient agar

b) Yeast extract phosphate agar

6. Which of the following incubation temperature is most suitable for the proper growth of Campylobacter jejuni?

a) 4°C 

b) 30°C 

c) 42°C      

d) Room temperature (25°C )

7. What is the suitable pH range for the proper growth of most of the clinically important bacteria?

a) pH 4- 5

b) pH 6.5- 7.5    

c) pH 7

d) pH 7-10 

8. Which of the following agar is most commonly general purpose medium used for the isolation of pathogenic fungi?

a) Columbia colistin nalidixic acid (CNA) agar 

b) Eosin-Methylene blue agar

c) Sabouraud Dextrose with Brain Heart Infusion (SABHI) agar      

d) Xylose Lysine Deoxycholate agar (XLD agar)

9. Thiosulfate-Citrate-Bile-Salt Sucrose Agar (TCBS agar) is a selective medium for isolation of............................

a) Mycobacterium tuberculosis 

b) Salmonella typhi

c) Streptococcus pneumoniae

d) Vibrio cholerae    

10. What is the purpose of the use of  the Cornmeal agar with Tween 80 and trypan blue?

a) Identification of Candida albicans and its chlamydospores   

b) Isolation and identification Identification of Cryptococcus neoformans  (niger seed agar)

c) Isolation and identification of dimorphic fungus Blastomyces dermatidis

d) Isolation and identification of Clostridium tetani and its spores

11. All of the following fastidious bacteria can be isolated using the selective Chocolate agar, Except

a) Brucella spp

b) Haemophilus spp 

c) Candida albicans

d) Neisseria spp

12. Which of the following culture media contains inhibitors to suppress bacterial growth, making it selective for fungi? 

a) Czapek-Dox Agar

b) MacConkey Agar 

c) Sabouraud Dextrose Agar (SDA) 

d) Sabouraud Chloramphenicol Agar 

13. Which of the following is the correct pH range that promote the growth of the fungi and inhibit the growth of bacteria in Sabouraud Dextrose Agar (SDA)?

a) pH 5- 6

b) pH 6.5- 7.5  

c) pH 7

d) pH 9

14. Which of the following agar is a selective medium used for the isolation of filamentous fungi?

a) Bird Seed Agar

b) Czapek-Dox Agar 

c) Xylose Lysine Deoxycholate agar

d) Mannitol salt agar (MSA)

15. Which of the following agar is a differential, yeast extract agar for the isolation of Shigella spp and Salmonella spp?

a) Bird Seed Agar

b) New York City (NYC) agar

c) Sabouraud Dextrose Agar (SDA) 

d) Xylose lysine deoxycholate (XLD) agar

Answers:

1. a) Enrichment media, b) Selective media and c) Differential media. Otitis media is not a culture/agar medium, it is a term for ear infection.

2. a) Brain Heart Infusion (BHI) media. MacConkey agar is a differential media used for the isolation of lactose fermenting gram negative bacteria. Columbia colistin nalidixic acid (CNA) agar is a selective medium used for the isolation of gram positive cocci. Chocolate agar is a medium used for the isolation of gram negative cocci (Neisseria spp)

3. d) Phenylethyl alcohol, it inhibits gram negative bacteria

4. b) 50°C 

5. d) Yeast extract phosphate agar

6. c) 42°C 

7. b) pH 6.5- 7.5   

8. c) Sabouraud Dextrose with Brain Heart Infusion (SABHI) agar 

9. d) Vibrio cholerae 

10. a) Identification of Candida albicans and its chlamydospores

11. c) Candida albicans, it is a yeast

12. d) Sabouraud Chloramphenicol Agar, chloramphenicol inhibits the growth of bacteria.

13. a) pH 5- 6, a low pH in SDA inhibits the growth of bacteria.

14. b) Czapek-Dox Agar, contains sodium nitrate, potassium chloride, magnesium sulfate, and other nutrients that support the growth of filamentous fungi while inhibiting the growth of bacteria and yeasts.

15. d) Xylose lysine deoxycholate (XLD) agar, inhibits the growth of gram positive bacteria.