Question

Information about Streptococcus mutans (tooth decay)

Morphology- COCCI

Arrangement- STEPTOCOCCI

Capsule- POLYSACCHARIDE

Enveloped or Non- enveloped-

Type of genome, DNA OR RNA, SINGLE OR DOUBLE STANDED-

SIZE-

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Epidemiology (Incidence, Prevalence, Person, Place, Time, Relative facts)

Virulence (Describe ability to cause disease; how are host defense inhibited or evaded; how does microbe gain nutrition from host)

Etiology and Transmission: (Reservoir, Mode of transmission, Location of infection, Physical & Medical Symptoms), Drugs, Mechanism of drugs.

Answer 1

Streptococcus mutans-

Morphology and arrangement-

1.They are gram positive cocci shaped facultative anaerobes that can thrive in temperatures ranging from 18 to 40degree celsius. First isolated in 1924 by J.Killian Clarke. It is a human oral pathogen responsible for tooth decay and dental caries.

2. They are homofermentive.

3.S. mutans forms homogenous group based on several phenotypic characteristics.

Capsule-

1. They contain thick cell wall and retains a gentian violet. The cell wall is composed of peptidoglycan and teichoic acids . S.mutans has a capsule that is composed of polysaccharide and it's structural subunit is dextran glucose. The S.mutans have the ability to attach to the tooth surface and form a biofilm. They are enveloped.

Genome structure-

S.mutans have extracellular circular DNA and has atleast three closely related plasmids.The size of these plasmids are similar, approximately 5.6 kilobase. These plasmids are important to S.mutans because of their resistance to certain antibiotics. There are no bacteriophage genome present in S.mutans. They are completely sequenced. Four genes are for glucan binding proteins.

Virulence- the main factors associated with cariogenecity include adhesion, acidogenecity and acid tolerance. Each of these properties work together to cause dental plaque. The S.mutans contain a cell bound protein glycosyl transferase that serves as an adhesin for attachment to the tooth and as an enzyme that polymerized dietary sugars into glucans that leads to the formation of plaque.