Clinical Microbiology: Streptococcus and Enterococcus

Microbiology

An overview of the taxonomy, classification, virulence, and laboratory identification of Streptococcus and Enterococcus species.

Bacteriology Clinical Pathology Infectious Diseases

15 Questions Hard Ages 18+ Oct 10, 2026

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About this Study Set

This study set covers Microbiology through 15 practice questions. An overview of the taxonomy, classification, virulence, and laboratory identification of Streptococcus and Enterococcus species. Every question includes the correct answer so you can learn as you go — pick any format above to get started.

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Browse all 15 questions from the Clinical Microbiology: Streptococcus and Enterococcus study set below. Each question shows the correct answer — select a study format above to practice interactively.

1 What is the primary characteristic of the Gram stain for the genus Streptococcus?

A Gram-negative rods
B Gram-positive cocci in chains
C Gram-positive diplococci
D Gram-negative spirilla

2 Which test is used to differentiate Streptococcus and Enterococcus from the catalase-positive Staphylococci?

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

3 What does the Lancefield grouping system classify based on?

A Hemolysis pattern
B Cell-wall carbohydrate antigens
C Morphology
D Sugar fermentation

4 Which type of hemolysis is characterized by complete lysis of red blood cells and a clear area around the colony?

A Alpha
B Beta
C Gamma
D Alpha-prime

5 Which organism is the primary cause of neonatal sepsis and meningitis?

A S. pyogenes
B S. pneumoniae
C S. agalactiae
D E. faecalis

6 Which virulence factor of S. pyogenes is responsible for its antiphagocytic properties and is a major determinant of virulence?

A M protein
B Hyaluronidase
C Streptokinase
D DNase

7 Which test demonstrates the synergistic effect of the CAMP factor produced by S. agalactiae?

A Optochin test
B CAMP test
C Bile-esculin test
D Bacitracin test

8 Which species is known for being lancet-shaped diplococci and is optochin-susceptible?

A S. pyogenes
B S. agalactiae
C S. pneumoniae
D E. faecium

9 What is the key distinguishing feature of Enterococcus regarding its environment?

A Strict aerobe
B Salt tolerant (6.5% NaCl)
C Requires high CO2
D Acidophile only

10 Which test is positive for both S. pyogenes and Enterococcus?

A PYR hydrolysis
B Hippurate hydrolysis
C Optochin sensitivity
D Bacitracin sensitivity

11 What does the Neufeld (Quellung) reaction confirm?

A Hemolysis
B Capsular swelling
C Catalase production
D Salt tolerance

12 Which toxin is associated with the skin rash of scarlet fever?

A Streptolysin O
B Streptokinase
C Streptococcal pyrogenic exotoxin
D Hyaluronidase

13 Which organism is intrinsically resistant to vancomycin?

A S. pyogenes
B E. faecalis
C Pediococcus
D S. agalactiae

14 What is the primary clinical significance of the Viridans streptococci group?

A Neonatal meningitis
B Subacute bacterial endocarditis
C Toxic shock syndrome
D Impetigo

15 Which enzyme, produced by S. pyogenes, acts as a spreading factor by breaking down hyaluronic acid?

A Streptodornase
B Hyaluronidase
C Protease
D Neuraminidase

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