Antibacterial Properties of Cinamaldehyde and its Impact on Biofilm Formation by Respiratory Isolates of Corynebacterium Propinquum

Objective: Analyze the antibacterial properties of cinnamaldehyde (CN) and its effect on biofilm formation by Corynebacterium propinquum. Theoretical Framework: C. propinquum can form biofilm and be multiresistant. In the context of advancing resistance and the need for new and more effective drugs, constituents extracted from cinnamon, such as CN, stand out as they have proven antimicrobial activity. Method: It was investigated whether CN essential oil (EO) was hemolytic for sheep erythrocytes. The antibacterial activity against nasopharyngeal C. propinquum strains was evaluated by determining the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC), and by analyzing the combinatorial effect with chloramphenicol (CL). Biofilm formation on a hydrophobic surface (polystyrene), in the presence or absence of subinhibitory concentrations (SubMIC) of CN, was also evaluated. Results and Discussion: The results demonstrated that CN was not hemolytic. Despite the MIC being higher than that of CL, the antibacterial action was strong for both strains, but it was impossible to determine the MBC. The combinatorial antibacterial effect of CN+CL demonstrated partial synergy or indifference. Weak biofilm formation was observed for the strains and the presence of CN SubMIC, although it did not change the pattern, increased its production. Research Implications: This research's practical and theoretical implications suggest promising antibacterial properties of CN on emerging pathogen C. propinquum. Originality/Value: This study is relevant not only because it demonstrates aspects of virulence of a pathogen that has been little studied, but also because it shows the antibacterial action of CN, a constituent of an easily accessible spice. It highlighted the possibility of future research into the treatment of infections caused by a microorganism that is often multi-resistant.