Control of the Food-Borne Pathogen, Shigella flexneri 1457 by Using a Plant Polyphenol Naringenin

The most contagious forms of shigellosis and bacterial dysentery are caused by the gram-negative bacteria Shigella flexneri. Antibiotics like ciprofloxacin and synthetic antimicrobial agents are used to treat this infection; however, their limitations in terms of human health and antibiotic resistance call for better drugs for treatment. Polyphenols, being plant-derived, have the potential to be an effective agent for bacterial infections. Flavonoids, naturally occurring antioxidants with antibacterial properties, can disrupt biofilm formation and reduction, which aids in the treatment. The objective of this work is to investigate the function of naringenin in the prevention of biofilm and antibacterial activity against S. flexneri. Naringenin was shown to inhibit both the growth and biofilm formation of S. flexneri at a concentration of 1000 μg/mL. Scanning electron microscopy results indicated the morphological changes of S. flexneri following treatment with naringenin. Fluorescent-activated cell sorting revealed an 87.76% increase in dead cells with naringenin (1000 μg/mL). Upon treatment with naringenin, downregulation of adhesion (yebL), quorum-sensing (rcsC, sdiA), and biofilm development (s0482) associated genes was observed through qRT-PCR analysis.