Isolation and Typing of and from Caries-active Subjects.

BACKGROUND

and are main etiological agents of dental caries.

AIM

The aim of the study was to isolate, identify, characterize, and determine the minimum inhibitory concentration (MIC) of and from caries-active subjects.

MATERIALS AND METHODS

Sixty-five plaque samples were collected from caries-active subjects aged between 35 and 44 years, processed and cultured on mitis salivarius bacitracin agar. All the bacterial isolates were subjected to morphotyping and the suspected colonies were identified by 16S rDNA sequencing. The and strains were characterized by biotyping and phylogenetic analysis. The MIC of ampicillin and erythromycin was determined by microtiter plate method.

RESULTS

Of the study population, 41 isolates displayed typical colony morphologies of and . The 16S rDNA sequencing results revealed that 36 isolates were and 5 isolates were . The biotyping of these isolates demonstrated three biotypes, namely, biotype I ( = 35), biotype III ( = 1), and biotype IV ( = 2). However, 3 isolates exhibited variant biotypes. The phylogenetic analysis revealed that the clinical strains of and clustered independently along with respective reference strains. The average MIC of ampicillin and erythromycin against and was 0.047 μg/ml and 0.39 μg/ml, respectively.

CONCLUSION

The 16S rDNA sequencing was an impeccable method for and identification when compared with morphotyping and biotyping methods. The study also suggested that nonspecific bacteria might be involved in caries formation.