Antibacterial potential of indigenous plant extracts against multidrug-resistant bacterial strains isolated from New Delhi region

Abstract

The extensive use of antibiotics to treat bacterial infections has led to the widespread emergence of multidrug-resistant (MDR) pathogens, becoming increasingly difficult to treat with currently available antibacterial agents. The present study is based on prospecting the ethnomedicinal potential of Indian plant varieties for the treatment of MDR bacteria. Plants produce an array of diverse pharmacological compounds in defence against microbial pathogens which may be employed as a novel intervention strategy to combat MDR human pathogens. In the present study, the antimicrobial activity of extracts of four common Indian plants: Azadirachta indica (Neem), Murraya koenigii (Kadipatta), Phyllanthus emblica (Amla), and Ocimum sanctum (Tulsi) prepared in four solvents, water, methanol, ethanol, and chloroform was tested against nine MDR bacterial isolates. Kirby-Bauer well diffusion assays were adopted to assess the antimicrobial activity of plant extracts against the MDR strains. The potency of plant extracts was examined by determining the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). All MDR isolates including Staphylococcus haemolyticus, Bacillus subtilis, B. thuringiensis, B. cereus, Enterobacter xiangfangensis, Klebsiella pneumoniae, and Pseudomonas aeruginosa were significantly inhibited by the plant extracts. Test extracts showed promising antibacterial potential against MDR P. aeruginosa and Bacillus sp. with low MIC values ranging between 0.02-1.56 mg/ml, while most plant extracts exhibited either moderate MBC values or bacteriostatic effects. To the best of our knowledge, this is the first study that demonstrates the potential use of endemic A. indica, M. koenigii, P. emblica, and O. sanctum as therapeutic agents against circulating MDR human pathogens in the national capital.