MCQ on Microbial Culture and Identification (Medical Microbiology)

Multiple Choice Questions on Microbial Culture and Identification 

1) A bacteriological stain also known as the differential stain is used to identify acid-fast organisms, what is the name of the stain?
a)Negative stain
b) Gram stain
c) Ziehl-Neelsen stain
d) Schaeffer stain- Fulton stain

2) A Capsule is a....................layer lying outside the bacterial cell and can be found in both gram-positive and gram-negative bacteria
a) Lipopolysaccharide layer
b) Polysaccharide
c) Phospholipid
d) None of the Above

3) Which of the following dye is commonly used for the Negative staining technique?
a) Crystal violet
b) India ink
c) Methylene blue
d) Iodine

4) All of the following are common bacteriological stains, Except:
a) Bismarck brown
b) Methylene blue
c) Eosin
d) Crystal violet 

5) Gram staining technique is used for the differentiation of gram-positive and gram-negative bacteria. What color do gram-negative bacteria show when observed under the microscope after the staining procedure?
a) Blue
b) Pink
c) Purple
d)Violet

6) MacConkey’s agar is both Selective and Differential media that is used primarily for the isolation of gram-negative bacteria. It consists of ................which inhibits the growth of gram-positive bacteria.
a) Blood
b) Peptone
c) Bile salts
d) Tryptophan

7) All of the following are lactose fermenting bacteria, except
a) Klebsiella pneumoniae
b) Escherichia coli
c) Enterobacter aerogenes
d) Pseudomonas aeruginosa

8) Which of the given bacteria has flagella and shows a positive motility test?
a) Staphylococcus aureus
b) Yersinia pestis
c) Klebsiella pneumoniae
d) Proteus vulgaris

9) The biochemical test helps in the identification and classification of microorganisms, there are many different types of this test, which of the following tests show a negative result for Escherichia Coli?
a) Lactose
b) Indole
c) Citrate
d) Glucose

10)The cultural characteristics of Clostridium perfringens are all of the given below, Except?
a) Microaerophilic
b) Spore-forming
c) Lecithinase positive
d) Stormy fermentation

11) …................is a rod-shaped, gram-positive, non-spore-forming medically important virulent foodborne pathogen that can grow in raw meat and vegetables, unpasteurized milk, cheese.
a) Bacillus cereus
b) Listeria monocytogens
c) Clostridium botulinum
d) Lactobacillus acidophilus

12)Which of the following microbe grows well and shows hemolytic properties in the blood agar?
a) Bacillus anthracis
b) Proteus vulgaris
c) Streptococcus pyogenes
d) Staphylococcus epidermidis

13) All of the statements regarding Bacillus anthracis are true, Except
a) The causative agent of smallpox
b) Nonhemolytic colonies appear on Blood agar
c) Commonly transmitted from animals to humans
d) Endospore-forming bacteria

14) Which of the following bacteria is a part of the human gut and mouth flora that is also important in making some fermented dairy products?
a) Candida albicans
b) Lactobacillus acidophilus
c) Staphylococcus aureus
d) Micrococcus luteus

15) …............is a fungus that is a part of normal gut flora and also a common skin, a vaginal and oral pathogen 
a) Neisseria gonorrhoea
b) Yersinia pestis
c) Coccidiodes immitis
d) Candida albicans
e) Penicillium marneffei

16) Which of the following organism of the Enterobacteriaceae family have the characteristics of swarming growth on culture media, produces urease enzyme, and important urinary tract pathogen?
a) Proteus spp
b) Salmonella spp
c) Lactobacillus spp
d) Klebsiella spp

17) ................is a gram-negative bacillus, encapsulated, lactose fermenter. show mucoid. It is also a part of the normal flora of the oral cavity, skin, and intestine.
a) Pseudomonas aeruginosa
b) Staphylococcus aureus
c) Streptococcus pneumoniae
d) Klebsiella pneumoniae

18) Which of the following media is one of the important and common media for the proper isolation of cocci pathogens such as Haemophilus spp and Neisseria gonorrhoea?
a) Potato dextrose agar
b) Chocolate agar
c) Nutrient agar
d) Mac Conkey agar

19) All of the statements are true about Corynebacterium spp, Except
a) Requires selective media containing tellurite
b) Gram-positive
c) Colonies appear black or gray
d) Motile

20) Mannitol Salt agar consisting of high salt concentration is both selective and differential media used for the isolation of which of the following gram-positive cocci?
a) Klebsiella spp
b) Streptococcus spp
c) Staphylococcus spp
d) Pseudomonas spp

21) Which of the following media is used for the routine bacteriological isolation of Salmonella and Shigella spp?
a) Xylose lysine deoxycholate agar
b)Thiosulfate citrate bile salts agar
c) Mannitol salt agar
d) Bile esculin agar

22) Which of the following selective media is used for the cultivation and isolation of Neisseria gonorrhoeae and N. meningitidis?
a) Buffered charcoal- yeast extract agar
b)Thayer martin agar
c)Xylose lysine deoxycholate agar
d) Bile esculin agar

23) All of the following statements are correct about the common bacteriological media known as  Sheep blood agar, Except
a) It consists of 5% of sheep blood
b) Used for the identification of common fastidious bacteria
c) It helps in the isolation and identification of hemolytic bacteria 
d) Used as a selective media for the growth of Mycobacterium tuberculosis

24) Select all the most common clinically important spore-forming bacteria
a) Bacillus anthracis
b) Aspergillus flavus
c) Lactobacillus acidophilus
d) Clostridium perfringes
e) Haemophilus influenzae

25) Biochemical tests are a common and conventional laboratory procedure in the differentiation and identification of enteric bacteria, which of the following test result (Indole, methylene, Voges-Proskauer, and Citrate) is correct in the identification of E.coli?
a) IMViC (+,+,-,-)
b) IMViC ( +,-,+,+)
c) IMViC ( -,-,+,-)
d) IMViC (+,-,+,-)

26) Select all the common specimens collected for the laboratory diagnosis of dermatophytes
a) Nail clippings
b) Skin scrapings
c) Hair 
d) Urine
e) Blood

27) Which of the following are the routine diagnostic methods for the microbial examination of blood specimen collected from a patient with a high fever for more than 2 days?
a) Direct microscopic examination
b) Culture media
c) Serodiagnosis 
d) Antibiotic susceptibility test
e) All of the above

28) Which of the following methods are the most common and routine culture methods performed in the microbiology lab for the proper isolation and identification of bacteria and fungi? Select all the correct answers
a) Streak culture/ surface plating
b) Stab culture
c) Pour plate culture
d) Liquid culture





Multiple Choice Answers
1(c), 2(b), 3(b), 4(a), 5(b), 6(c), 7(d), 8(d), 9(c), 10(a),
11(b), 12(c), 13(a), 14(b), 15(d), 16(a), 17(d), 18(b), 19(d), 20(c), 
21(a), 22 (b), 23 (d), 24 (a) and (d), 25 (a), 26 (a), (b) and (c), 27 (e), 28 a), b), c) and d)

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