Objectives: The frequency of occurrence of the family
Bifidobacteriaceae in human dental root caries was studied. Samples (n=19 from 17 patients), were obtained from sound exposed root surfaces and from root caries lesions ranging in severity from arrested to soft caries. Methods:
Bifidobacteriaceae were isolated on mupirocin-containing trypticase phytone selective media, Gram-stained and subcultured for identification. Total anaerobic counts were determined using FAA medium. Presumptive identification was based on morphological and growth characteristics, biochemical tests including detection of fructose-6-phosphate phosphoketolase, carbohydrate fermentation profiles and detection of α-galactosidase, α-glucosidase. DNA was extracted and the isolates were identified using genus-specific PCR primers in combination with 16S rRNA sequencing. The 16S rRNA sequence data were subjected to BLAST searching and analysed using the RDP (http://rdp.cme.msu.edu/). Results: A total number of 322 isolates were identified, 250 were
Bifidobacterium dentium, 24 were
B. subtile, 1 was
B. breve, 8 were
Parascardovia denticolens, 7 were
Scardovia inopicata, and 5 were identified as
S. genomosp. C1. The remaining 27 isolates could not be identified using the present primer pairs.
B. dentium was present in 15 out of 19 samples.
B. subtile in 3 out of 19 (3 different lesions in same patient),
P. denticolens in 2 out of 19,
S. inopicata in 2 out of 19,
S. genomosp. C1 in 2 out of 19 and
B. breve in 1 sample.
Bifidobacteriacae formed 7.4±3.0 per cent of the microbiota from the soft lesions which was significantly greater (p=0.003) than from the other sample types. Conclusion: The
Bifidobacteriacae of root carious lesions was found to be more complex than previously reported and there was a clear tendency of an increased prevalence of bifids with root lesion severity and no
Bifidobacteriacae were isolated from healthy exposed root surface dentine or from arrested root caries lesions.
Funded by KCL Dental Institute.