Antimicrobial effect of cinnamon oil, L-lysine, and beta-carotene on multi-drug resistant Listeria monocytogenes isolated from milk and dairy products

Abstract

Despite many achievements in developed countries mainly in health and food sectors, L .monocytogenes remains a great challenge in food industries. This study was developed to determine the prevalence and antimicrobial resistance patterns of L. monocytogenes in Egyptian dairies. Furthermore, some phytochemicals such as cinnamon oil, L-lysine, and beta-carotene were used as antilisterial additives in soft cheese as a food substrate. A total of 150 dairy samples (raw milk, farm bulk tank milk, yogurt, Kareish cheese, white soft cheese (Damietta), and ice cream, 25 each) were screened to determine the prevalence of Listeria spp. The results revealed that 5, 10, 8, 6, 3, and 2 samples of bulk tank milk, market raw milk, Kariesh cheese, soft cheese, yogurt, and ice cream were contaminated with Listeria spp., respectively. The antimicrobial resistance profiling showed that 100% of L .monocytogenes (12 isolates) revealed resistance to penicillin G, amoxicillin/clavulanate, piperacillin/tazobactam, cefoxitin, and cefepime. Furthermore, molecular characterization revealed that all L. monocytogenes harbored the hylA virulent gene. Application of some phytochemicals such as cinnamon oil and L-lysine significantly (p<0.05) reduced L. monocytogenes growth in soft cheese artificially contaminated with L. monocytogenes, while beta-carotene did not reveal any significant (p<0.05) growth inhibition during 28 days of storage. In conclusion, Egyptian dairy products are considered a vehicle for the transmission of L. monocytogenes, thus strict hygienic measures should be adopted from farm to fork. In addition, cinnamon oil and L-lysine are considered good candidates for dairy sectors as food preservatives.