Antibacterial and antibiofilm properties of Azadirachta indica (Neem), Aloe vera (Aloe vera), and Mentha piperita (Peppermint) against multidrug-resistant clinical isolates

Abstract

Background: Misuse of antibiotics globally has resulted in the development of resistant bacterial strains. One of the sole reasons for bacteria being resistant to antibiotics is the production of biofilm. Biofilms are microbial communities which get adhere to solid surfaces easily and pose an important virulence factor for causing many chronic infections. Therefore, there is an urge to find out new potential sources which can be used as an alternative to the existing antibiotics. Methods: The present study was conducted on three medicinal plant extracts Azadirachta indica, Aloe vera, and Mentha piperita to assess their antibacterial and antibiofilm properties against 58 multidrug-resistant clinical isolates using agar well diffusion method, minimum bactericidal concentration (MBC), and crystal violet modified assay at 50, 25, 12.5, and 6.25 mg/ml concentration. Results: A. indica showed a maximum zone of inhibition of (17.8 ± 1.52 mm) and (18.1 ± 1.45 mm) at 50 and 25 mg/ml concentration. Biofilm inhibition was more than 80% for Staphylococcus aureus and Pseudomonas aeruginosa and MBC came out to be 6.25 ± 2.96–6.25 ± 4.91 mg/ml (mean range). A. vera showed the highest zone of inhibition for S. aureus (18.2 ± 1.48 mm) at 50 mg/ml concentration followed by Staphylococcus saprophyticus (17.8 ± 1.48 mm) and Staphylococcus epidermidis (18.0 ± 1.60 mm). Biofilm inhibition was seen more than 50% and MBC was 50 ± 23.14–50 ± 25.72 mg/ml (mean range). Conclusion: All the three plant extracts were effective, but A. indica and A. vera were found to be more potent than M. piperita.