Evaluation of the Efficacy of Some Natural Products Against Methicillin-Resistant Staphylococcus aureus Biofilms by Scanning Electron Microscopy.

Several highly antibiotic-resistant infections are caused by methicillin-resistant Staphylococcus aureus (MRSA) due to its ability to form biofilms. Antibiofilm strategies cannot be developed without the use of comprehensive microscopic techniques. This study aimed to examine the antibiofilm activity of linoleic acid, ferulic acid, vanillic acid, and iso-vanillic acid against the MRSA and its biofilm. The microdilution method was used to study the antibacterial activity of selected natural products against MRSA in vitro. SEM was used to examine the effect of selected natural products on the degradation of extracellular polymeric substances of MRSA biofilms. Metabolic activity was monitored using the tetrazolium (MTT) assay. SEM images revealed that sub-inhibitory concentrations of linoleic acid, vanillic acid, ferulic acid, and isovanillic acid significantly prevented MRSA cell adhesion, and altered bacterial morphology. Whereas, treatment of mature biofilms with higher concentrations of vanillic acid, linoleic acid, ferulic acid, and isovanillic acid resulted in significant destruction of biofilms and their extracellular polymeric substances. Linoleic acid, ferulic acid, vanillic acid, and iso-vanillic acid, therefore, could help in the prevention of MRSA biofilm formation, and the removal of preformed biofilms, which will lead to the development of combinatorial strategies against biofilm-related MRSA infections.