Streptococcus mutans

Streptococcus-mutans.jpg

Streptococcus mutans (Fig 1.) is a spherical shaped, gram positive bacteria belonging to the Streptcoccaceae family. All bacteria from this family are gram positive, facultatively anaerobic and have complex nutritional requirements. Streptococcus mutans specifically has been found to be a main cause of dental caries or tooth decay in humans.




In Human Oral Cavity

S. mutans is well suited to living in the human oral cavity. It tolerates temperatures ranging from 18-40 degrees celcius and will readily metabolize carbohydrates. The high carbohydrate diet of humans and many animals makes this area a suitable habitat. S.mutans will ferment carbohydrates primarily into lactic acid via the phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS). The lactic acid produced builds in the mouth and causes the destruction of minerals in human teeth, leading to tooth decay. Streptococcus mutans is usually found in the small pits and crevasses present in human teeth and is easily transferred from one person to another. Children are especially susceptible to the acid build up caused by it's presence.
When present in the human oral cavity, S. mutans will usually form or attach to a biofilm. In this state, studies have shown it to be over 1,000 times as resistant to antibiotics making it's removal difficult. If the concentration of medication required to remove it was administered, it would more likely be toxic to the human than the bacteria. Despite this, the method with most success has been to physically remove the bacteria, by either brushing regularly or dental scraping.




References:
1) F.A Skinner, L.B Quesnel. "Streptococci". London, Academic Press. 1978.

2) Academon Term Papers and Essays. http://www.academon.com/Descriptive-Essay-Streptococcus-Mutans/106830. Accessed: 08/02/11.

3) http://www.microscopesblog.com/2010_08_01_archive.html. Picture Accessed: 08/02/11.

4) Science Direct. http://www.sciencedirect.com/science. Accessed: 08/02/11