View source for Microbewiki:''Streptoccus mutans'' and Dental Caries

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What is ''Streptococcus mutans''?

Contents

[Classification]

[S. mutans and dental caries]

[Biofilm]

[S. mutans and early childhood caries]

[References]

[[File:Streptococcus_mutans_01.jpg‎]] 

Gram Stain of ''Streptoccus mutans''.  CDC/Dr. Richard Facklam.  1975.

''Streptococcus mutans'' 
is a Gram positive streptococcus bacterium that inhabits human teeth and has been demonstrated to be the primary bacterial cause of dental caries (commonly known as cavities).  ''S. mutans'' is part of the normal flora or normal microbiota of humans, so the presence of ''S. mutans'' in the mouth does not automatically cause dental caries.  

Here is a culture of ''Streptococcus mutans'' grown in the laboratory: 

[[File:Hedetniemi_Liao_Streptococcus_mutans_luria_agar_37_C.jpg‎]] 

LA plate streaked with Streptococcus mutans and incubated at 37ºC for 24 hours
   
Hedetniemi, Kevin and M-K, Liao. 2006.  Luria Broth (LB) and Luria Agar (LA) Media and Their Uses: Streptococcus mutans. Furman University, Greenville, SC. http://www.microbelibrary.org/index2.php?option=com_resource&controller=article&Itemid=73&article=3033. 25 April 2013.


Want to know more about how ''S. mutans'' causes cavities? 
See the [S. mutans and dental caries] page. 

References:
* Image 1043, Public Health Image Library.  CDC website.  
  http://phil.cdc.gov/phil/details.asp?pid=1043

* Tortora, G. J., Funke, B. R., and Case, C. L. ''Microbiology: An Introduction'', Tenth edition.  2010 Pearson Education, Inc.

Classification

h2 Classification of ''Streptococcus mutans''

''Streptoccus mutans'' is a gram positive bacterium.

* Domain: Bacteria
* Phylum: Firmicutes (low G-C, Gram + bacteria)
* Class: Bacilli 
* Order: Lactobacillales 
* Family:Streptococcaceae
* Genus: Streptococcus
* Species: ''Streptococcus mutans''


Note: Historically, ''Streptococcus mutans'' has sometimes been categorized in the group mutans Streptococci, a group of oral bacteria discovered concurrently.  More recently, it has been realized that the original researchers had actually cultured multiple species that were not as related as they believed.  
For more explanation on the various oral bacteria related to ''Streptococcus mutans'', follow this link to a tutorial:

http://www.ncl.ac.uk/dental/oralbiol/oralenv/tutorials/streps.htm 


References:

* Allmann, Amber.  ''Streptococcus mutans''.  Wiki.    
http://bioweb.uwlax.edu/bio203/s2007/allmann_ambe/  
* Image 1043, Public Health Image Library.  CDC website.  
  http://phil.cdc.gov/phil/details.asp?pid=1043

h2 The role of ''Streptococcus mutans'' in dental caries

 

h3 What are dental caries?
* dental caries areas of decay brought on by bacterial infections of the teeth 
* dental caries are considered to be an infectious disease
 
[[File:Toothdecaystages_wikieducator.jpeg‎]]  

Open content from WikiEducator.org

This figure shows the progression of dental caries from affecting only the outer surface of the tooth (enamel caries) to more advanced forms of decay in which inner tooth structures are also affected.  Different species of bacteria are involved in these stages of dental caries.  ''Streptoccus mutans'' is associated with the early stage, enamel caries.  

h3 How do caries form?
* ''Streptococcus mutans'' exist as part of the normal flora of the mouth

* ''S. mutans'' adhere to the teeth as part of a [biofilm] 

* other species of bacteria join this mass of ''S. mutans'' bacteria on the teeth

     * ''Actinomyces'' attaches by extensions called fimbriae to the dextran (a sugar) that ''S. mutans'' secretes 

* ''S. mutans'' metabolizes sucrose (table sugar) and secretes lactic acid as a byproduct

* lactic acid can demineralize the teeth, leading to indentations in the enamel that are called cavities

* ''S. mutans'' is involved in enamel caries, but other bacteria are more abundant in later stages of caries



References:


* Oral Health in America: A Report of the Surgeon General.  Ch. 3: Dental and Periodontal Infections.     
  http://www.nidcr.nih.gov/datastatistics/surgeongeneral/sgr/chap3.htm
* Tortora, G. J., Funke, B. R., and Case, C. L.  ''Microbiology: An Introduction'', Tenth edition.  2010 Pearson Education, Inc.  p. 81, 163, 431, 707-708


h3 Biofilms

h2 What is a biofilm? 
* a coating (film) of bacteria (bio) that adhere to one another and to a surface
* Biofilms are made up of the bacteria (or other microbes) and also a matrix of sugars and other polymeric substances that connect the cells to one another.  

[[File:Sauer_Biofilms_and_Biocomplexity.png‎]]

Figure adapted from "Biofilms and Biocomplexity."  Karin Sauer, Alex. H. Rickard, and David G. Davies.  The biofilm developmental process in stages. (1) reversible attachment, (2) irreversible attachment, (3 & 4) maturation and (5) dispersion.


h2 Some common biofilms:

* dental plaque
* shower scum
* algae on swimming pool walls 

Bacteria in biofilms communicate and form pillars so that water and nutrients can flow past each of them.


Here is a biofilm on glass shower door:
 
 {image:worksite:/Wiki figures/shower scum_windowcleaningz dotcom_2.jpg|shower scum_windowcleaningz dotcom_2.jpg}


And here is a swimming pool wall bearing a biofilm of algae:

 {image:worksite:/Wiki figures/algae_biofilm_pool.png|algae_biofilm_pool.png}




h2 Why do biofilms matter?

Biofilms are stubborn against techniques like brushing and even antibiotics or disinfectants, so dental plaque will still build up even if a person does brush his teeth.  This is why regular cleanings are important: the tools the hygienist uses can help to remove the plaque from teeth.


References:
* Marsh, P.D.  "Dental Plaque as a Microbial Biofilm."  ~~Caries Research~~.  2004.
* Sauer, K., Rickard, A. H., and Davies, D.G.  "Biofilms and Biocomplexity." ~~Microbe~~, 2007, 2:7, p. 350.   
* Tortora, G. J., Funke, B. R., and Case, C. L.  ~~Microbiology: An Introduction~~, Tenth edition.  2010 Pearson Education, Inc. p. 81, 163, 431, 707-708


h2 Early Childhood Caries (ECC)

[[File: Green-baby-bottle-md.png‎]]

* Early Childhood Caries, also known as ECC, is defined by the American Dental Association as a condition of currently decayed teeth, teeth that are missing due to caries, or fillings for caries occurring in a child between 0 years and just under 6 years old (71 months).
* One major risk factor for the development of early childhood caries is the continual intake of sugary drinks from baby bottles.  Dentists generally recommend that children not be sent to bed with a bottle because of this risk.         
* The effects of ECC may be more severe than the effects of adult caries.  
* ECC tends to occur in higher rates among "disadvantaged populations."
* In the United States, Alaskan native and American Indian populations are one group that experiences a higher than normal prevalence of ECC. 



References:
* de Silva-Sanigorski1, A. M., Calache, H., Gussy, M., Dashper, S., Gibson, J., Waters, E.  "The VicGeneration Study: A Birth Cohort to Examine the Environmental, Behavioural and Biological Predictors of Early Childhood Caries: Background, Aims and Methods."  ~~BMC Public Health~~, 2010, 10:97.  
http://www.biomedcentral.com/1471-2458/10/97
* "Statement on Early Childhood Caries."  American Dental Association.
http://www.ada.org/2057.aspx
* "2010 Symposium on Early Childhood Caries in American Indian and Alaska Native Children." Council on Access, Prevention and Interprofessional Relations.   American Dental Association, 2011.
http://www.ada.org/sections/professionalResources/pdfs/2010_ecc_symposium_report.pdf


h2 References


 
* Allmann, Amber.  ~~Streptococcus mutans~~.  Wiki.    
http://bioweb.uwlax.edu/bio203/s2007/allmann_ambe/ 

* de Silva-Sanigorski1, A. M., Calache, H., Gussy, M., Dashper, S., Gibson, J., Waters, E.  "The VicGeneration Study: A Birth Cohort to Examine the Environmental, Behavioural and Biological Predictors of Early Childhood Caries: Background, Aims and Methods."  ~~BMC Public Health~~, 2010, 10:97.  
http://www.biomedcentral.com/1471-2458/10/97

* Forssten, S., Björklund, M., and Ouwehand, A. C. "~~Streptococcus mutans~~, Caries and Simulation Models."  ~~Nutrients~~ 2010, 2, 290-298.     

* Marsh, P.D.  "Dental Plaque as a Microbial Biofilm."  ~~Caries Research~~.  2004.

* Oral Health in America: A Report of the Surgeon General.  Ch. 3: Dental and Periodontal Infections.     
  http://www.nidcr.nih.gov/datastatistics/surgeongeneral/sgr/chap3.htm

* Image 1043, Public Health Image Library.  CDC website.  
  http://phil.cdc.gov/phil/details.asp?pid=1043

* Sauer, K., Rickard, A. H., and Davies, D.G.  "Biofilms and Biocomplexity." ~~Microbe~~, 2007, 2:7, p. 350.   
http://www.microbemagazine.org/images/stories/arch2007/july07/znw00707000347.pdf 

* "Statement on Early Childhood Caries."  American Dental Association.
http://www.ada.org/2057.aspx

* "2010 Symposium on Early Childhood Caries in American Indian and Alaska Native Children." Council on Access, Prevention and Interprofessional Relations.   American Dental Association, 2011.
http://www.ada.org/sections/professionalResources/pdfs/2010_ecc_symposium_report.pdf    

* Tortora, G. J., Funke, B. R., and Case, C. L. ~~Microbiology: An Introduction~~, Tenth edition. 2010 Pearson Education, Inc. p. 81, 163, 431, 707-708