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Questions and Answers
What constitutes the principal marker for potentially pathogenic streptococci in cultures of throat swabs or other clinical samples?
Which type of hemolysis is the principal marker for potentially pathogenic streptococci in cultures of throat swabs or other clinical samples?
Which type of Streptococci can be serologically classified using a common C carbohydrate according to Lancefield classification?
Which test differentiates Group A Streptococci from other Streptococci?
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What is the function of the E.CAMP Test (Christie Atkins Munch Petersen Test)?
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Which classification does the Pyogenic 10 C - 37 C + 45 C - Viridance - + + refer to?
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What is the basis of classification for Streptococci and Enterococci?
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Which type of Streptococci produces a clear, colorless zone of hemolysis around it?
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Which Streptococcus group is associated with incomplete or partial hemolysis?
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What kind of zone of hemolysis is characteristic of Beta-hemolytic Streptococci?
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Lancefield grouping is used for classification based on what characteristic of Streptococci?
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Which type of Streptococci is more likely to appear in chains when grown in broth cultures?
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Which hemolysin is oxygen-stable and non-antigenic?
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Which virulence factor of Group B Streptococci is known for its antiphagocytic properties?
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Which exotoxin causes Scarlet Fever?
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What is the function of Lipoteichoic acid and Protein F?
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Which Streptococcus species has small, transparent, and smooth colonies with beta-hemolysis?
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Which test is used to measure Streptolysin O levels?
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Study Notes
Streptococcus Characteristics
- Streptococcus spp. belong to the family Streptococcaceae
- Inhabit various sites, notably the upper respiratory tract, and live harmlessly as commensals
- Catalase-negative, gram-positive cocci, usually arranged in pairs or chains
- Cells of Enterococci and some Streptococci appear more elongated than spherical
- Streptococcal cells are more likely to appear in chains when grown in broth cultures
- Most members are aerotolerant anaerobes (but behave like facultative anaerobes)
- Some species are capnophilic
Hemolysis
- Alpha hemolysis: partial hemolysis, greenish discoloration around the colony
- Beta hemolysis: complete hemolysis, sharply defined, clear, colorless zone of hemolysis
- Gamma hemolysis: no hemolysis
Lancefield Classification
- Based on the group-specific C carbohydrate (polysaccharide) antigen
- Used to classify Streptococci serologically
Streptococcus Groups
- Group A: S. pyogenes, β-hemolysis, Lancefield group A
- Group B: S. agalactiae, β-hemolysis, Lancefield group B
- Group C: S. equisimilis, β-hemolysis, Lancefield group C
- Group D: Enterococci, α-hemolysis, Lancefield group D
- Group F: S. bovis, non-hemolytic, Lancefield group F
Laboratory Tests
- Bacitracin Susceptibility Test (Taxo A): differentiates Group A Streptococci from other Streptococci
- CAMP Test (Christie Atkins Munch Petersen Test): test for Group B Streptococci
- Gram Stain: gram-positive cocci in pairs or chains
- Cultural Characteristics: pinpoint colonies, β-hemolysis
- J. Leucine Aminopeptidase Test: detects J. Leucine aminopeptidase enzyme
- SXT Susceptibility Test: detects susceptibility to SXT antibiotic
- Serological Tests: detects antibodies against Streptococci
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Description
Test your knowledge on the classification and characteristics of Streptococci, including colony appearance, growth preferences, and serological classification based on Lancefield classification. Learn about the significance of ß-hemolysis in identifying potentially pathogenic streptococci.
