Antimicrobial Effect of Essential Oils on Multidrug-Resistant Salmonella typhimurium in Chicken Fillets

Abstract

Chicken meat, which could be a healthy and nutritionally food, is regrettably incriminated as a source of Salmonella typhimurium which has a great ability to cause human salmonellosis. This study aimed to assess the prevalence of multidrug-resistant S. typhimurium in chicken meat and the effects of essential oils on its viability. A total of 300 chicken meat and its products samples were streaked on XLD agar plates, which was followed by identification of the isolates based on biochemical and serological tests. Ten isolates were serotyped as S. typhimurium then assayed for susceptibility to 14 antimicrobials by the single diffusion method. Eight isolates (80%) showed multiple antimicrobial resistance (MAR) for 3 or more antimicrobials with MAR index of 0.4857 in average. Serotyped S. typhimurium strain with the highest antimicrobial resistance, confirmed by 16s RNA sequencing, was selected for studying the effects of thyme, oregano, and lemon essential oils with concentrations of 0.5, and 1% on its viability after inoculating into chicken fillets by intensity of 3.0×106 and on sensory traits of chicken fillets on 2nd, 4th, 6th, and 8th days of inoculation during cold storage (4ºC). All results showed a significant reduction of S. typhimurium counts with highest inhibition obtained using 1% lemon essential oil. The sensory properties of treated chicken fillets were improved by all used essential oils, compared to the control samples after 6th day, and 8th day of the storage period. The samples treated with 0.5, and 1% lemon essential oil revealed the highest improvement of sensory attributes. This study proved that the majority of S. typhimurium existing in chicken meat are Multidrug-resistant and have no negative effect on sensory traits, hence, posing a public health hazard. Natural essential oils have, also, great antimicrobial effect on S. typhimurium, thus it could replace chemical antimicrobials.