Questions and Answers
What are the important characteristics of all Streptococci?
catalase (-), G(+) cocci in chains
Which of the following are important Streptococci species? (Select all that apply)
How is the categorization of streptococci based?
hemolysis on blood agar: alpha, beta or gamma-hemolytic, cell-wall carbohydrate detected by Lancefield grouping
Which Streptococcus is an example of alpha-hemolytic streptococci?
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Which Streptococcus is an example of beta-hemolytic streptococci?
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What is an example of gamma-hemolytic streptococci?
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Lancefield grouping is detected by lab _____ techniques.
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Lancefield grouping is especially useful in telling if you have ____.
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Which species is associated with Lancefield Group A?
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Which species is associated with Lancefield Group B?
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Which species is associated with Lancefield Group D?
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Which species is considered non-typeable in Lancefield grouping?
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Study Notes
Important Characteristics of Streptococci
- Catalase negative
- Gram-positive cocci arranged in chains
Important Streptococci Species
- Streptococcus pyogenes: Known as Group A strep
- Streptococcus agalactiae: Known as Group B strep
- Streptococcus pneumoniae: Significant pathogen
- Streptococcus bovis: Categorized as Group D strep
- Viridans streptococci: A diverse group of oral bacteria
Categorization of Streptococci
- Based on hemolysis patterns on blood agar: alpha, beta, or gamma-hemolytic
- Lancefield grouping identifies cell-wall carbohydrates: Groups A-D and others
Alpha-Hemolytic Streptococci
- Characterized by partial lysis of red blood cells (RBCs)
- Notable examples include S. pneumoniae and Viridans streptococci (noted for greenish appearance)
Beta-Hemolytic Streptococci
- Characterized by complete lysis of RBCs
- Key species are S. pyogenes and S. agalactiae (identified by a yellow halo around colonies)
Gamma-Hemolytic Streptococci
- Non-hemolytic; do not lyse RBCs
- Includes strains such as S. bovis and Viridans streptococci
Lancefield Grouping Techniques
- Involves agglutination lab techniques for classification
- Essential for identifying specific streptococcal infections
Clinical Relevance of Lancefield Grouping
- Particularly useful in diagnosing strep throat
Specific Lancefield Groups
- Group A (GAS): Identified as S. pyogenes
- Group B (GBS): Identified as S. agalactiae
- Group D (GDS): Includes S. bovis and Enterococcus species
- Non-typeable species: S. pneumoniae and Viridans streptococci
Review of Streptococcus Classification
- Recap of hemolytic patterns and Lancefield grouping for clinical and laboratory identification
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Test your knowledge on the classification and characteristics of Streptococci with these flashcards. Understand the different species, their important traits, and how they are categorized. Perfect for microbiology students and professionals alike!
