MCQ on Microbial Culture and Identification (Medical Microbiology)

Multiple Choice Questions on Microbial Culture and Identification

1) A bacteriological stain also known as 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 both gram positive and gram negative bacteria
a) Lipopolysaccharide layer
b) Polysaccharide
c) Phospholipid
d) None of the Above

3) Negative staining is the technique where the background of a specimen is stained whereas positive staining stains the whole specimen. Which dye is required 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

6) MacConkey’s agar is both Selective and Differential media 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 positive motility test?
a) Staphylococcus aureus
b) Yersinia pestis
c) Klebsiella pneumoniae
d) Proteus vulgaris

9) The biochemical test helps in 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, when grown on Blood agar, are all of the given below, Except?
a) Microaerophilic
b) Spore-forming
c) Lecithinase positive
d) Stormy fermentation

11) … a rod-shaped gram-positive, a non-spore forming organism that can cause foodborne illness in human and animals. It can grow at very low temperature on a wide variety of food including raw meat, raw vegetables, unpasteurized milk, cheese, etc., and is considered one of the most virulent foodborne pathogenic bacteria.
a) Bacillus cereus
b) Listeria monocytogens
c) Clostridium botulinum
d) Lactobacillus acidophilus

12)Which of the given organism when grown in blood agar media is classified according to its hemolytic properties?
a) Bacillus anthracis
b) Proteus vulgaris
c) Streptococcus pyogens
d) Staphylococcus epidermidis

13) All of the statements for Bacillus anthracis are true except
a) Grows aerobically as well as anaerobically
b) Nonhemolytic colonies on Blood agar
c) Major foodborne pathogen
d) Endospore-forming bacteria

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

15) … part of human normal gut flora and also a clinically important pathogen, it's infection can lead to symptoms such as itchy skin, itchy genital area, white coat on the tongue and mouth ulcers, constipation. When grown in the lab, the organism produces green pigmented colonies on CHROMagar.
a) Streptococcus mutans
b) Mycobacterium tuberculosis
c) Proteus mirabilis
d) Candida albicans

16) Which of the following organism of the Enterobacteriaceae family have the characteristics of swarming growth on culture media, produces urease enzyme, do not usually ferment lactose and is mainly the cause of urinary tract infections and nosocomial infections?
a) Proteus spp
b) Salmonella spp
c) Lactobacillus spp
d) Klebsiella spp

17) a gram-negative bacillus, encapsulated, lactose fermenter and show mucoid colonies on media. 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) …......... is a blood agar media prepared by slowly heating the media at 80 degree Celsius until it becomes brown, it is used for the isolation of some important pathogenic organisms 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 for Corynebacterium spp, except
a) Requires selective media containing tellurite
b) Gram-positive
c) Colonies appear black or gray
d) Motile

20. Mannitol Salt agar is both selective and differential media, it is used for the isolation of ................, the high salt concentration inhibits the growth of gram-negative bacteria.
a) Micrococcus spp
b) Streptococcus spp
c) Staphylococcus spp
d) Corynebacterium spp

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(c), 14(b), 15(d), 16(a), 17(d), 18(b), 19(d), 20(c)

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