Gram-Positive Cocci MCQs

  1. Which of the following organisms is classified as a Gram-positive cocci?
    • A) Escherichia coli
    • B) Staphylococcus aureus ✅
    • C) Pseudomonas aeruginosa
    • D) Klebsiella pneumoniae

  2. What is the main difference between Staphylococcus and Streptococcus species?
    • A) Shape
    • B) Gram staining characteristics
    • C) Catalase test ✅
    • D) Oxygen requirements

  3. Which of the following Gram-positive cocci is coagulase-positive?
    • A) Staphylococcus epidermidis
    • B) Streptococcus pyogenes
    • C) Staphylococcus aureus ✅
    • D) Enterococcus faecalis

  4. Which test is used to differentiate Streptococcus pneumoniae from Viridans streptococci?
    • A) Catalase test
    • B) Coagulase test
    • C) Optochin sensitivity test ✅
    • D) Novobiocin sensitivity test

  5. Which of the following is a characteristic feature of Streptococcus pyogenes?
    • A) Alpha-hemolysis
    • B) Beta-hemolysis ✅
    • C) Gamma-hemolysis
    • D) No hemolysis

  6. Which Gram-positive cocci is most commonly associated with urinary tract infections?
    • A) Streptococcus pneumoniae
    • B) Enterococcus faecalis ✅
    • C) Staphylococcus aureus
    • D) Neisseria gonorrhoeae

  7. What virulence factor is associated with Staphylococcus aureus that allows it to cause food poisoning?
    • A) Exotoxin A
    • B) Enterotoxin ✅
    • C) Streptolysin O
    • D) Lecithinase

  8. Which of the following is the primary site of infection for Streptococcus pneumoniae?
    • A) Skin
    • B) Lungs ✅
    • C) Gastrointestinal tract
    • D) Urinary tract

  9. The Lancefield classification is based on:
    • A) Capsule formation
    • B) Hemolytic properties
    • C) Carbohydrate composition of cell wall ✅
    • D) Antibiotic resistance

  10. Which test differentiates Staphylococcus saprophyticus from Staphylococcus epidermidis?
    • A) Catalase test
    • B) Coagulase test
    • C) Novobiocin sensitivity test ✅
    • D) Optochin sensitivity test

  11. Which Gram-positive cocci is commonly associated with neonatal sepsis?
    • A) Staphylococcus aureus
    • B) Streptococcus agalactiae ✅
    • C) Enterococcus faecium
    • D) Streptococcus pyogenes

  12. Which of the following is a common cause of infective endocarditis?
    • A) Enterococcus faecalis ✅
    • B) Streptococcus pyogenes
    • C) Staphylococcus saprophyticus
    • D) Bacillus anthracis

  13. What type of hemolysis is exhibited by Streptococcus pneumoniae?
    • A) Alpha-hemolysis ✅
    • B) Beta-hemolysis
    • C) Gamma-hemolysis
    • D) No hemolysis

  14. Which Gram-positive cocci is known for producing a thick, mucoid capsule that aids in virulence?
    • A) Staphylococcus epidermidis
    • B) Streptococcus pyogenes
    • C) Streptococcus pneumoniae ✅
    • D) Enterococcus faecium

  15. Which of the following is a group D Streptococcus?
    • A) Streptococcus pyogenes
    • B) Streptococcus agalactiae
    • C) Enterococcus faecalis ✅
    • D) Streptococcus pneumoniae

  16. Which Gram-positive cocci can grow in 6.5% NaCl?
    • A) Streptococcus pneumoniae
    • B) Staphylococcus aureus
    • C) Enterococcus faecalis ✅
    • D) Streptococcus pyogenes

  17. What is the typical arrangement of Streptococcus bacteria under a microscope?
    • A) Clusters
    • B) Chains ✅
    • C) Pairs
    • D) Tetrads

  18. Which Gram-positive cocci is associated with toxic shock syndrome?
    • A) Streptococcus pneumoniae
    • B) Enterococcus faecalis
    • C) Staphylococcus aureus ✅
    • D) Streptococcus pyogenes

  19. Which antibiotic is typically used to treat Methicillin-resistant Staphylococcus aureus (MRSA)?
    • A) Penicillin
    • B) Vancomycin ✅
    • C) Amoxicillin
    • D) Ciprofloxacin

  20. Which of the following species is commonly known as Group A Streptococcus?
    • A) Streptococcus pneumoniae
    • B) Streptococcus agalactiae
    • C) Streptococcus pyogenes ✅
    • D) Streptococcus bovis
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