Identification of biofilm producing bacterial species causing dental caries and their sensitivity to zoocin A and clove hydroalcoholic extract

Abstract

Introduction: Dental caries is an infectious disease mostly associated with streptococcal species, especially Streptococcus mutans, as the main etiologic agent. Zoocin A protein is extracted as a recombinant protein from Streptococcus zooepidemicus and Escherichia coli with high effect on S. mutans. Clove extract has also been shown to have antimicrobial effects on several bacterial species, such as S. mutans. Objectives: The purpose of this study was to isolate and identify common bacteria causing dental caries and their susceptibility to zoocin A and clove extract. Patients and Methods: This study was performed on 133 dental caries samples in Tehran province. The isolates were identified by phenotypic and molecular methods. Molecular identification was performed by 16S rRNA gene sequence. The effects of antibiotics, zoocin A and clove extract were studied. Results: There was no significant difference between men and women regarding dental caries (P=0.422), but age group of 16-30 years were the most common (P=0.002). Dominant biofilm forming bacteria identified with 16srRNA analysis including S. mutans, S. mitis, S. sanguinis, S. gordonii, Lactobacillus gasseri, Jemela hemolysin, and Granulicatella adiacens. Zoocin A exhibited a strong inhibitory effect with minimum inhibitory concentration (MIC) range of 2-4 µg/mL mostly against S. mutans. MIC of hydroalcoholic extract of clove was 8-16 µg/mL. Conclusion: Streptococcal species were predominant causes of tooth decay. Zoocin A and clove extract showed antimicrobial activity even on antibiotic-resistant and biofilm-forming species causing tooth decay.