5

Question 1

1. What is the primary structural difference between gram-positive and gram-negative bacteria?
   a) The presence of a thicker peptidoglycan layer in gram-negative bacteria
   b) The presence of an outer membrane in gram-positive bacteria
   c) The presence of lipopolysaccharides in gram-negative bacteria
   d) The presence of teichoic acids in gram-negative bacteria

Answer 1

C

Question 2

2. What component of the gram-negative bacteria’s outer membrane is detected by the immune system?
   a) Teichoic acid
   b) Lipid A
   c) O-polysaccharide
   d) Peptidoglycan

Answer 2

C

Question 3

3. What is the purpose of the mordant iodine in the Gram staining procedure?
   a) It stains the peptidoglycan layer
   b) It causes the crystal violet to stick to the bacterial cell wall
   c) It dissolves the outer membrane of gram-negative bacteria
   d) It counterstains gram-negative bacteria

Answer 3

B

Question 4

4. Which of the following is a characteristic feature of Gram-positive bacteria?
   a) A thin peptidoglycan layer
   b) Presence of an outer phospholipid bilayer
   c) The presence of teichoic and lipoteichoic acids in the peptidoglycan layer
   d) A high lipid content in the cell wall

Answer 4

C

Question 5

5. What is the main distinguishing feature of Gram-negative bacteria in a Gram stain?
   a) A thicker peptidoglycan layer
   b) Presence of a counterstain that makes them appear red
   c) The lack of a cytoplasmic membrane
   d) The ability to retain crystal violet dye

Answer 5

B

Question 6

6. Which of the following organisms is a Gram-negative aerobic cocci?
   a) Staphylococcus aureus
   b) Streptococcus pneumoniae
   c) Neisseria meningitidis
   d) Enterococcus faecalis

Answer 6

C

Question 7

7. What type of bacteria are classified as Gram-positive aerobic cocci and are often differentiated by the coagulase test?
   a) Streptococci
   b) Staphylococci
   c) Enterococci
   d) Bacilli

Answer 7

B

Question 8

8. What does a positive coagulase test for Staphylococci indicate?
   a) The bacterium is pathogenic
   b) The bacterium is commensal
   c) The bacterium is a Gram-negative rod
   d) The bacterium can cause pneumonia

Answer 8

A

Question 9

9. Which of the following bacteria is most commonly associated with causing urinary tract infections (UTIs) and is a Gram-negative aerobic bacillus?
   a) Streptococcus pneumoniae
   b) Escherichia coli
   c) Staphylococcus aureus
   d) Neisseria gonorrhoeae

Answer 9

B

Question 10

10. Which of the following bacteria causes gastrointestinal infections and is a Gram-negative aerobic bacillus?
    a) Salmonella spp.
    b) Staphylococcus epidermidis
    c) Streptococcus pyogenes
    d) Clostridium difficile

Answer 10

A

Question 11

11. What is the role of the lipopolysaccharide (LPS) in Gram-negative bacteria?
    a) It stabilizes the peptidoglycan layer
    b) It forms a protective barrier against antibiotics
    c) It anchors the outer membrane to the cytoplasmic membrane
    d) It is a primary component of the bacterial flagellum

Answer 11

B

Question 12

12. What does the Gram stain reveal when testing for a Gram-negative bacillus like Escherichia coli?
    a) Red rods with a thin peptidoglycan layer and outer membrane
    b) Blue cocci with a thick peptidoglycan layer
    c) Green cocci with partial hemolysis
    d) Yellow rods with no outer membrane

Answer 12

A

Question 13

13. Which of the following bacterial genera is classified as Gram-positive aerobic cocci that can be further divided into alpha, beta, and non-hemolytic species?
    a) Staphylococci
    b) Streptococci
    c) Neisseria
    d) Enterobacteria

Answer 13

B

Question 14

14. Which of the following Gram-positive bacteria is most commonly associated with cellulitis, bone and joint infections, endocarditis, and bacteremia?
    a) Staphylococcus epidermidis
    b) Streptococcus pneumoniae
    c) Staphylococcus aureus
    d) Streptococcus pyogenes

Answer 14

C

Question 15

15. Which method is used to test for antibiotic resistance and sensitivity in cultured bacteria?
    a) Gram staining
    b) Coagulase test
    c) Antibiotic resistance and sensitivity plate
    d) Time of flight (TOF) mass spectrometry

Answer 15

C

Question 16

16. When obtaining a blood sample for culture, what is a key indicator that the bacteria are metabolizing and causing an infection?
    a) The bacteria produce CO2, which changes the color of the discs in the blood culture bottles
    b) The bacteria produce antibiotics, which prevent growth on agar plates
    c) The bacteria do not grow on any agar medium
    d) The bacteria exhibit no change in color or growth patterns

Answer 16

A

Question 17

17. Which of the following is the primary reason for conducting a Gram stain on a blood culture sample?
    a) To differentiate between viral and bacterial infections
    b) To identify the presence of bacteria and determine their Gram characteristics
    c) To determine the presence of antibiotics in the bloodstream
    d) To identify the presence of fungal organisms

Answer 17

B

Question 18

18. Which Gram-negative bacterium can cause infections such as urethritis, cervicitis, and pelvic inflammatory disease?
    a) Escherichia coli
    b) Neisseria gonorrhoeae
    c) Salmonella spp.
    d) Staphylococcus aureus

Answer 18

B

Question 19

19. Which of the following bacteria is responsible for causing meningitis and is a Gram-negative aerobic cocci?
    a) Streptococcus pneumoniae
    b) Neisseria meningitidis
    c) Enterococcus faecalis
    d) Listeria monocytogenes

Answer 19

B

Question 20

20. What is the most common clinical syndrome caused by Staphylococcus aureus?
    a) Pneumonia
    b) Cellulitis, bone and joint infections
    c) Gastroenteritis
    d) Urinary tract infection

Answer 20

B