Tuesday, May 17, 2011

New Dental Caries Causing Species of Bacteria Identified

Streptococcus Mutans
As reported in the Journal of Clinical Microbiology.
A team of scientists from Boston has confirmed that the bacterium Streptococcus mutans is a primary culprit in early childhood caries (EEC) cavities on the first set of teeth, and has identified a new species of bacterium, Scardovia wiggsiae, which they suspect is also a major contributor.
Here is the abstract of the original paper.

Cultivable anaerobic microbiota of severe early childhood caries.


The Forsyth Institute, 245 First Street, Cambridge, MA 02142. annetanner@forsyth.org.


Severe early childhood caries (ECC), while strongly associated with Streptococcus mutans using selective detection (culture, PCR), has also been associated with a widely diverse microbiota using molecular cloning approaches. The aim of this study was to evaluate the microbiota of severe ECC using anaerobic culture. The microbial composition of dental plaque from 42 severe ECC children was compared with that of 40 caries-free children. Bacterial samples were cultured anaerobically on blood and acid (pH 5) agars. Isolates were purified, and partial sequences for the 16S rRNA gene were obtained from 5,608 isolates. Sequence-based analysis of the 16S rRNA isolate libraries from blood and acid agars of severe ECC and caries-free children had >90% population coverage, with greater diversity occurring in the blood isolate library. Isolate sequences were compared with taxon sequences in the Human Oral Microbiome Database (HOMD), and 198 HOMD taxa were identified, including 45 previously uncultivated taxa, 29 extended HOMD taxa, and 45 potential novel groups. The major species associated with severe ECC included Streptococcus mutans, Scardovia wiggsiae, Veillonella parvula, Streptococcus cristatus, and Actinomyces gerensceriae. S. wiggsiae was significantly associated with severe ECC children in the presence and absence of S. mutans detection. We conclude that anaerobic culture detected as wide a diversity of species in ECC as that observed using cloning approaches. Culture coupled with 16S rRNA identification identified over 74 isolates for human oral taxa without previously cultivated representatives. The major caries-associated species were S. mutans and S. wiggsiae, the latter of which is a candidate as a newly recognized caries pathogen.

Now, there is a need to develop strategies to combat these additional bacteria besides regular dental care and various mouth rinses (chlorhexidine, Povodine iodine and fluoride). There has also been the hope of the development of an anti-caries vaccine but research continues.

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