Anti-biofilm activity of Azadirachta indica and Ocimum sanctum Aqueous Extract Combination against MRSA

Abstract

The objective of the current work is evaluate phytochemicals in Azadirachta indica (Indian Lilac; Neem) and Ocimum sanctum (Holy Basil; Tulsi) extracts and study the anti-biofilm activity alone or in-combination against MRSA. Azadirachta indica and Ocimum sanctum aqueous extracts were prepared based on ayurvedic principles, tested for phytochemicals, and examined for biofilm inhibiting potential on methicillin-sensitive and methicillin-resistant S. aureus strains alone or in fixed-dose combination. Both Azadirachta indica and Ocimum sanctum extracts were detected with alkaloids, flavonoids, glycosides, sugars and protein. The crude extracts maximally inhibited biofilm formation of MRSA1 at 60-70%. The concentrated extract of Azadirachta indica dose-dependently inhibited the biofilm formation of methicillin-sensitive S. aureus (MSSA) and –resistant S. aureus strains (MRSA1 and MRSA2) with maximum inhibition of 67, 50 and 45% respectively. Likewise, Ocimum sanctum extract also exhibited maximum biofilm inhibition of 48, 35 and 45% respectively. Further, combination of the concentrated extracts of Azadirachta indica and Ocimum sanctum exhibited a very significant biofilm inhibition of > 80% in both sensitive and resistant strains. The combination of Azadirachta indica and Ocimum sanctum extracts prepared as per ayurvedic principles is effective in inhibiting biofilm formation of MSSA and MRSA. This finding may also be experimented further with pathogens like Pseudomonas aeruginosa, Klebsiella pneumoniae, Acetanobacter baumanii for anti-biofilm activity. Also, this combination can be used as an organic disinfectant in place of synthetic sanitizers since the former can eradicate the pathogens colonized in the environmental surfaces to avoid co-infection in situations like COVID-19 pandemic.