Date of Award

Spring 2023

Thesis Type

Open Access

Degree Name

Honors Bachelor of Arts

Department

Biology

Sponsor

Dr. Brendaliz Santiago-Narvaez

Committee Member

Dr. Paul Stephenson

Committee Member

Dr. Matthew Forsythe

Abstract

Streptococcus mutans is the known etiological agent of dental caries. S. mutans’ virulence factors, namely biofilm formation and lactic acid fermentation, contribute to its pathogenic behavior within the oral cavity. Biofilms are thick, antibiotically resistant communities of bacteria that are much more difficult to treat than planktonic or free-floating bacteria. Continued misuse of antibiotics against dynamic communities, like biofilms, has led to increased research on non-antibiotic alternatives. Amongst these alternatives, there are silver and silver-based compounds. Silver is commonly incorporated into medicine due to its inhibitory and bactericidal effects and antibacterial properties. Silver (I) cyanoximates have demonstrated promising antibacterial activity against various microorganisms that colonize the surfaces of subcutaneous medical devices. To study the antimicrobial properties of silver (I) cyanoximates, specifically Silver(I) Nitrosodicyanomethanide (Ag(ACO)) and Silver(I)α-Oximido-(2-benzoyl)acetonitrile (Ag(BCO)), aerobic and anaerobic growth curves, hydroxyapatite (HA) disc assays, and in vivo treatment assays were performed against S. mutans UA159. Both compounds inhibited planktonic growth aerobically and anaerobically at concentrations between 32 ug/mL and 128 ug/mL. Both compounds also inhibited biofilm formation on HA discs at concentrations between 64 ug/mL and 128 ug/mL. To test whether the compounds showed antibacterial activity in-vivo, Galleria mellonella larvae were used. All concentrations of Ag(BCO) and Ag(ACO) successfully eliminated, limited, or delayed bacterial infection in G. mellonella larvae compared to S. mutans UA159 control. Continued research on antibiotic alternatives that target and disrupt biofilm-forming microorganisms contributes to the general understanding of how to treat S. mutans biofilms. This may lead to the incorporation of silver (I) cyanoximates in the prevention and treatment of dental caries and other biofilm-related infections.

Rights Holder

Jill Hughes

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