Detection and Categorization of Biofilm-forming Staphylococcus aureus, Viridans streptococcus, Klebsiella pneumoniae, and Escherichia coli Isolated from Complete Denture Patients and Visualization Using Scanning Electron Microscopy.

AIMS: Complete denture patients have a plethora of microorganisms inhabiting their complete dentures. Some bacteria are capable of causing systemic illness such as aspiration pneumonia and infective endocarditis. Hence, detection as well as the categorization of biofilms, which form on the denture surface is vital in the study of denture biofilm-associated local and systemic diseases. This study aimed at the detection and categorization of biofilm-forming Staphylococcus aureus, Viridans streptococcus, Klebsiella pneumoniae, and Escherichia coli isolated from complete dentures and visualization of biofilms using scanning electron microscopy (SEM). MATERIALS AND METHODS: Thirty complete denture patients were selected for the study and swabs were collected from their complete denture surfaces. Isolation of the bacteria was done using selective media and confirmed using biochemical tests and 16SrRNA sequencing. The bacteria were subjected to biofilm assays via Microtiter plate assay. The biofilm-forming bacteria were categorized as weak, moderate, and strong biofilm formers based on optical density (OD) values. As a visual confirmation of the biofilms, scanning electron microscopic (SEM) images were taken for each of the strong biofilm-forming bacteria. Descriptive statistical analysis was carried out with the help of Statistical Package for the Social Sciences (SPSS) statistical package version 20.0. RESULTS: The average OD of S. aureus was 1. 333±0. 015 and the average OD of V. streptococcus species was 1. 304 ± 0.023. The average OD value of K. pneumoniae was 0.8 ± 0.012 and the average value of E. coli was 1.014 ± 0.01. CONCLUSIONS: The study of biofilms especially the strongly biofilm formers is very useful to understand the potential pathogenic effect of biofilms. These biofilms cause the systemic spread of the planktonic bacteria which could lead to systemic diseases that are resistant to conventional treatment. This could be due to the inherent nature of the biofilm to offer drug resistance to existing antibacterial agents.