Abstract: Cronobacter sakazakii is an opportunistic pathogen transmitted by foods, which has been implicated in several forms of neonatal infections such as bacteraemia, necrotizing enterocolitis and neonatal meningitis. The aim of this study was to evaluate the antibacterial activity of plant-derived compounds to obtain potent antimicrobials. The antibacterial activity against C. sakazakii was determined by the Oxford cup method. Moreover, the minimum inhibitory concentration (MIC) against four American Type Culture Collection (ATCC) strains and five foodborne isolates was assessed using agar dilution method. Results indicated that 40 phytochemicals had obvious bacteriostatic action against C. sakazakii, and the diameters of the inhibition zones produced by 7 compounds (carvacrol, thymoquinone, thymol, cinnamaldehyde, citral, protocatechuic acid and protocatechualdehyde) were more than 13 mm. Among to 50 compounds tested, thymol and carvacrol had the most potent antimicrobial activity against 9 C. sakazakii strains with MICs ranging from 0.1 to 0.2 mg/mL. Thymoquinone, cinnamaldehyde, citral and protocatechualdehyde also demonstrated good antibacterial effect with MICs of 0.30 to 1.25 mg/mL. The MICs of ferulic acid, chlorogenic acid, syringic acid, lipoid acid, protocatechuic acid, epicatechin, caffeic acid, paeonol and cichoric acid ranged from 2.50 to 5.00 mg/mL. These findings suggest that some plant-derived compounds exhibit good antimicrobial effect against C. sakazakii strains and could be potentially used to control C. sakazakii during food processing, circulation and storage.

Key words: Cronobacter sakazakii, plant-derived compounds, growth inhibition zone, minimum inhibitory concentration