Streptococcus Taxonomy Quiz

Questions and Answers

What are the four main groups into which Streptococcus bacteria are often clustered?

Anaerobic streptococci (correct)

Other streptococci (correct)

Oral streptococci (correct)

Pyogenic streptococci (correct)

What was the family of the genus Streptococcus in the first edition of Bergey's manual?

Streptococcaceae

Which two new genera were created from species previously in the genus Streptococcus?

Enterococcus and Lactococcus

What is the domain and phylum of the genus Streptococcus?

Bacteria, Firmicutes Signup and view all the answers

List three types of hemolytic patterns.

Beta-hemolysis, Alpha-hemolysis, Gamma-hemolysis Signup and view all the answers

Match the following groups of streptococci with their characteristics:

S.pyogenes = Beta-hemolytic S.agalactiae = Beta-hemolytic S.pneumoniae = Alpha-hemolytic S.mitis = Alpha-hemolytic S.mutans = Alpha-hemolytic Signup and view all the answers

Who developed the serologic classification scheme for streptococci?

Rebecca Lancefield Signup and view all the answers

All streptococci have Lancefield antigens.

False Signup and view all the answers

What caused the outbreak associated with Streptococcus suis in pigs in China in 2005?

Contact with or consumption of infected pigs Signup and view all the answers

What are the general characteristics of Streptococcus members?

Gram-positive, non-motile, non-sporeforming, fastidious nutrition Signup and view all the answers

What is the G+C content range of streptococci genomes?

34-46% Signup and view all the answers

Study Notes

Taxonomy

Genus Streptococcus is large and complex, categorized into four main groups.
Pyogenic streptococci: Includes S. pyogenes (causes strep throat) and S. agalactiae.
Oral streptococci: Notably includes S. mutans (associated with dental caries) and S. pneumoniae.
Anaerobic streptococci: Includes S. morbillorum.
Other streptococci: Includes S. bovis.

Taxonomy History

First included in Bergey's manual under family Streptococcaceae, which had ten genera.
Major revisions since 1980 led to the creation of Enterococcus and Lactococcus from species within Streptococcus.

Taxonomy Present

Domain: Bacteria
Phylum: Firmicutes
Class: Bacilli
Order: Lactobacillales
Family: Streptococcaceae, now with three genera: Streptococcus, Lactococcus, Lactovum.

Groups

Sixteen S rRNA gene sequence analyses reveal seven multispecies phylogenetic units within Streptococcus sensu stricto.
Includes multiple groups: Pyogenic, S. bovis, S. anginosus, S. mitis, S. mutans, S. salivarius, and an unaffiliated group (S. suis).
Last four phylogenetic clusters are categorized as Viridans group streptococci.

Viridans Group Streptococci

Comprises a heterogeneous group that can act as commensal flora or pathogens in humans.
Inclusive of four phylogenetic clusters: Mitis, Mutans, Salivarius, and Anginosus.

Classification Schemes

Classification of Streptococcus spp. utilizes three schemes:
- Hemolytic pattern on sheep RBC
- Serologic properties
- Biochemical properties (fermentation/enzymes)

Hemolytic Pattern

Three main types of hemolysis:
- Beta-hemolysis: Complete lysis of RBC, clear zone.
- Alpha-hemolysis: Partial lysis, greenish color.
- Gamma-hemolysis: No lysis, no color change (non-hemolytic).
S. pyogenes and S. agalactiae are β -hemolytic; most human pathogens are α-hemolytic.

Serologic Properties

Developed by Rebecca Lancefield in the 1930s, based on group-specific antigenic composition (Lancefield antigens).
Classifies mainly β -hemolytic streptococci into groups A-T.
Group A includes S. pyogenes, B includes S. agalactiae, C includes S. equi, and D includes S. bovis.
S. pneumoniae and viridans streptococci are termed non-groupable.

Outbreak Associated with Streptococcus suis in Pigs (2005)

S. suis infection results from contact with or consuming infected pigs.
Outbreak linked to a single strain, confirmed through ribotyping.

General Properties

Gram-positive cocci or ovoid (0.5-2 μm), appear singly, in pairs, and chains.
Non-motile, non-sporeforming, some encapsulated.
Fastidious nutrition needs enriched media, facultative anaerobes, homofermentative (producing lactic acid from glucose fermentation).
Catalase-negative and oxidase-negative, distinguishing them from Neisseria species.
Susceptible to vancomycin.

Genomes of Streptococci

Genome sizes range from 1800-2500 kb; S. pyogenes is 1.9 Mb, S. pneumoniae is 2 Mb.
G+C content ranges from 34-46%, indicating low to medium G+C content.

Description

Test your knowledge of the taxonomy of Streptococcus bacteria. This quiz covers various groups within the genus, including pyogenic, oral, anaerobic, and other streptococci. Perfect for students and biology enthusiasts looking to deepen their understanding of these important microorganisms.