The Antibacterial Activity of Nanosilver Coupled Edible Plant Extracts Against Streptococcus mutans, the Cause of Dental Caries

Streptococcus mutans strains were found to have a substantial role in the development of caries. The objective of this study is to evaluate the potential antibacterial activity of some edible plant extracts against Streptococcus mutans isolates. Fifty oral dental plaque specimens were obtained from various dental clinics in Jeddah city from 23 males and 27 females with median ages ranging between 19.9 to 51.25 years. All isolates were subjected to microbiological, biochemical, and molecular identification. The results showed that 36.3% of the bacterial isolates were identified as Streptococcus mutans, 4.5% as Streptococcus gallolyticus, and 4.5% as Staphylococcus aureus followed by two Yeast species Candida albicans (45.4%) and Candida glabrata (9.0%). The PCR products of the size of 600 and 517 bp DNA fragments were successfully amplified from 16S rRNA and glucosyltransferase gene (gtfb) from the S. mutans isolates and reference strain ATCC25175. The gtfb sequences were submitted to NCBI and assigned accessions MW491783, MW491784, MW491785, and MW491786. Six plant extracts (Guava leaves, Olive Leaves, Clove, Garlic, Green Ginger, and Cinnamon), Nanosilver 25 nm, and 15% of two commercially available toothpastes (A and B) were evaluated against the S. mutans isolates by agar well diffusion test. Most plant extracts tested exhibited considerable inhibitory effects when coupled with Nanosilver 25 nm (1:1). Clove/SNP; 106.8±4.95, and Garlic/SNP; 105.3±3.2) had the greatest mean values of MIC, whereas (Olive/SNP) exhibited the lowest (56.5±3.89). In conclusion, although there are lot of studies on edible plant extracts, incorporating nanoparticles can synergistically increase its antibacterial effectiveness.