Evaluation of Matrix-Removed Moraxella catarrhalis Biofilm Susceptibility to Antimicrobial Photodynamic Therapy
Almarghalani, Abrar Abdulaziz
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Antimicrobial photodynamic therapy (aPDT) does not promote the development of antibiotic-resistant bacterial strains. Acute otitis media (AOM) and otitis media with effusion are common childhood disorders and a leading cause of health care visits worldwide. Otitis media (OM) is an inflammation of the middle ear that has serious complications which includes but is not limited to hearing loss. One of the most important factors that contribute to the development of OM is bacterial biofilm caused by Moraxella catarrhalis. The emergence of antibiotic-resistant bacteria is a major cause of treatment failure in children with OM. Therefore, it is important to search for an alternative treatment that will help in treating OM. Photodynamic therapy (PDT) has shown promising antimicrobial capabilities in treating biofilms but still shows lower effect against Gram-negative than Gram-positive bacteria. In this study PDT was used to reduce the Gram-negative strain of Moraxella catarrhalis biofilm protected viability with the help of a matrix-removal reagent – delmopinol that allows greater access of PDT to microbes in biofilms. Moraxella catarrhalis has been grown in planktonic cultures and as biofilms on microscopic slides. Each group of planktonic and biofilm samples was subjected to 3 main treatments compared with control group using only distilled water. These treatments included delmopinol alone, PDT alone, delmopinol then PDT. Assays for remaining bacterial viability with and without treatments including colony forming unit trials and confocal microscopy were performed. These data demonstrate that the delmopinol-treated biofilms were more susceptible to PDT than the control.