An investigation on anti-biofilm potential of Aegle marmelos fruit extract against multi-drug-resistant Staphylococcus aureus.

Background: Staphylococcus aureus, member of ESKAPEE pathogens is a noteworthy contributor to the global crisis rising due to antimicrobial resistance. Biofilms are the primary reason behind the increased antibiotic resistance and tolerance of pathogens. Hence targeting bacterial biofilms has been prioritized as an alternative strategy to counter antibiotic resistance. Aegle marmelos has gained prominence in Indian traditional medicine as seeds, fruits, leaves, bark and roots of this plant are being in use extensively in treating several kinds of ailments by the inhabitants of this subcontinent due to its ethno-pharmacological relevance. The fruit of this plant has been found with remarkable anti-bacterial properties along with other therapeutic efficacies. The present study aimed to identify the anti-biofilm potential of methanolic fruit extract of Aegle marmelos (AMFE) against multi-drug-resistant (MDR) S. aureus strains as a resort to counter the global crisis of antimicrobial resistance for alternative approaches.

Results: MBIC and MBEC of AMFE ranged between 100 and 200 µg.mL^-1 and 300-500 µg.mL^-1, respectively. AMFE could substantially reduce the carbohydrate and protein content of the exo-polymeric substance (EPS), crucial for biofilm production. Expressions of major biofilm promoting genes icaAD and its accessory sarA were down-regulated upon AMFE treatment as revealed from qRT-PCR analysis whereas the quorum sensing gene agr that promotes biofilm detachment was up-regulated. Fluorescence, scanning electron and atomic force microscopic studies confirm the reduction of biofilm biomass upon AMFE treatment. Up to 10 mg.mL^-1 AMFE was non-toxic to human lymphocytes with cell viability of 75.35%. GC-MS and FT-IR studies could detect the bioactive components where 9-octadecenoic acid, n-hexadecanoic acid, 9,12-octadecadienoic acid, methyl 4,7,10- hexadecatrienoate were the major components.

Conclusion: Anti-biofilm activity of AMFE towards MDR S. aureus have been established through in vitro biochemical and gene expression studies that were further substantiated by microscopic studies which reveal that AMFE could be explored in the management of S. aureus-associated infections.