gram+ cocci -

Gram-Positive Cocci MCQs

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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