Antibacterial and anti-biofilm activity of plumbagin against multi-drug resistant clinical bacterial isolates.

Abstract

To evaluate the antibacterial activity of plumbagin (PGN) against multidrug resistance (MDR) clinical isolates. This study was carried out at the Department of Clinical Lab Sciences, King Khalid University from October 6, 2021 to December 14, 2021. We investigated the antibacterial and anti-virulence activity of PGN against MDR Gram-negative (Escherichia coli, Klebsiella pneumoniae, Salmonella Typhi, and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus [S. aureus], Staphylococcus saprophyticus [S. saprophyticus], Streptococcus pyogenes, and Enterococcus faecalis) clinical bacterial isolates. Agar well diffusion, microdilution assay, colony count method, biofilm formation, and time-kill kinetics were employed to probe the MIC, MBC, and anti-virulence activity of PGN. Plumbagin inhibited the growth of all tested isolates, with S. saprophyticus exhibiting the highest sensitivity. MIC values ranged from 0.029 to 0.117 µg/mL whereas MBC ranged from 0.235 to 0.94 µg/mL, with 79% to 99% growth inhibition. Moreover, all tested isolates showed a marked decrease in biofilm formation, with S. saprophyticus and S. aureus being the most sensitive. Plumbagin is a stand-alone, broad spectrum antibacterial with promising potential against the rising threat of antimicrobial resistance.