Staphylococcus aureus MCQs Quiz: A Set of Questions, Options, and Answers

Introduction

Here is a Staphylococcus aureus MCQs Quiz Set with questions, options, and answers.

Staphylococcus aureus MCQs Quiz

1. What type of organism is Staphylococcus aureus?

A) Virus
B) Gram-positive bacterium
C) Gram-negative bacterium
D) Fungus

2. How does Staphylococcus aureus appear under Gram staining?

A) Gram-negative rods
B) Gram-positive cocci in clusters
C) Gram-positive bacilli
D) Gram-negative cocci in pairs

3. What is the natural habitat of Staphylococcus aureus?

A) Intestinal tract
B) Nasal cavity and skin
C) Blood
D) Respiratory tract

4. Which of the following diseases is NOT caused by Staphylococcus aureus?

A) Toxic shock syndrome
B) Pneumonia
C) Typhoid fever
D) Endocarditis

5. What is the key virulence factor of Staphylococcus aureus?

A) Capsule
B) Coagulase enzyme
C) Lipid A
D) Endospore

6. What is the common appearance of Staphylococcus aureus colonies on Mannitol Salt Agar (MSA)?

A) Pink colonies
B) Yellow colonies
C) Green colonies
D) Transparent colonies

7. Staphylococcus aureus can ferment which sugar on Mannitol Salt Agar (MSA)?

A) Glucose
B) Lactose
C) Mannitol
D) Sucrose

8. Which toxin is associated with Staphylococcus aureus food poisoning?

A) Shiga toxin
B) Enterotoxin
C) Exotoxin A
D) Cholera toxin

9. Which enzyme is used to distinguish Staphylococcus aureus from coagulase-negative staphylococci (CoNS)?

A) Catalase
B) Coagulase
C) Urease
D) Oxidase

10. What type of hemolysis does Staphylococcus aureus show on blood agar?

A) Alpha hemolysis
B) Beta hemolysis
C) Gamma hemolysis
D) No hemolysis

11. Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to which class of antibiotics?

A) Beta-lactams
B) Macrolides
C) Tetracyclines
D) Fluoroquinolones

12. What gene is responsible for methicillin resistance in MRSA?

A) mecA
B) blaZ
C) katG
D) rpoB

13. Which of the following is NOT a risk factor for Staphylococcus aureus infection?

A) Hospitalization
B) Indwelling catheters
C) Intravenous drug use
D) Vegetarian diet

14. What is the mechanism of action of enterotoxins produced by Staphylococcus aureus?

A) Inhibits protein synthesis
B) Acts as a superantigen
C) Breaks down cell walls
D) Disrupts DNA replication

15. Staphylococcus aureus biofilm formation is a major factor in which condition?

A) Urinary tract infection
B) Implant-associated infections
C) Gastroenteritis
D) Malaria

16. Which test confirms the presence of Staphylococcus aureus?

A) Catalase test
B) Coagulase test
C) Oxidase test
D) Urease test

17. What color does Staphylococcus aureus appear on Nutrient Agar?

A) White
B) Golden yellow
C) Green
D) Red

18. Which protein helps Staphylococcus aureus evade the immune system by binding to the Fc portion of antibodies?

A) Protein A
B) Protein G
C) Protein M
D) Protein E

19. Which antibiotic is the drug of choice for MRSA infections?

A) Vancomycin
B) Amoxicillin
C) Ciprofloxacin
D) Doxycycline

20. What is the mechanism of alpha-toxin produced by Staphylococcus aureus?

A) Pore formation in cell membranes
B) Inhibition of protein synthesis
C) DNA damage
D) RNA synthesis inhibition

Answer

1. B) Gram-positive bacterium
2. B) Gram-positive cocci in clusters
3. B) Nasal cavity and skin
4. C) Typhoid fever
5. B) Coagulase enzyme
6. B) Yellow colonies
7. C) Mannitol
8. B) Enterotoxin
9. B) Coagulase
10. B) Beta hemolysis
11. A) Beta-lactams
12. A) mecA
13. D) Vegetarian diet
14. B) Acts as a superantigen
15. B) Implant-associated infections
16. B) Coagulase test
17. B) Golden yellow
18. A) Protein A
19. A) Vancomycin
20. A) Pore formation in cell membranes