The Role of Biofilm Formation in Antibiotic Resistance of Bacteria Isolated from Saliva of Patients with Dental Caries

Objectives: This study aim to determine the bacterial diversity, biofilm forming ability and the antimicrobial resistance of bacteria isolated from saliva of patients with dental caries conditions with the using of 16S rRNA gene sequencing technique for identification of the most virulent isolates.

Methods: Isolation and identification of microorganisms were done employing standard bacteriologic techniques, followed by biofilm detection using tissue culture plate method. The strong biofilm forming isolates were selected for antibiotic susceptibility test against selected antibiotics using disk diffusion technique. In order to identify the selected isolates. The genomic DNA obtained following the extraction process were used for the amplification of the bacterial 16S rRNA gene.

Results: A total of 137 bacterial isolates were obtained and identified as belonging to 21 genera. Tissue culture plate (TCP) method were employed for screening the isolates according to its biofilm forming ability, its showed that 55 (40.1%) of the total isolates were strong, 57 (41.6%) were moderate and 25 (18.3%) were weak biofilm producers. The antimicrobial susceptibility test showed the multi antibiotics resistance of the strong biofilm former isolates to the conventional antibiotics. Enterococcus faecalis isolates showed the highest biofilm formation and antibiotic resistance. The 16S rRNA gene for two of these isolates have been amplified using PCR and the product sequenced, analyzed and registered in the National Center for Biotechnology Information (NCBI) as UKMS1 and UKMS2 and the accession numbers KX960104.1 and KX960105.1 respectively.

Conclusion: The study has revealed that antimicrobial resistance of bacteria isolates from saliva of patients with dental caries conditions is associated with biofilm formation. Other uncommon pathogenic bacteria were also isolated in this study as a result of the use of non-selective enrichment medium for culturing. Enterococcus faecalis isolates indicated the highest biofilm formation and antibiotic resistance.