In Vitro Antimicrobial Activity of Medicinal Plant Extracts against Some Bacterial Pathogens Isolated from Raw and Processed Meat

Background and aim: The poultry meat and its products are considered ideal media for bacterial growth and spoilage, as they are highly nutritive with a favorable pH. The food industry has focused its attention on a great diversity of plant species as food preservatives. The aim of this study was to investigate the presence of Staphylococcus aureus, Escherichia coli O157: H7, and Klebsiella pneumonia in food samples and to evaluate of the antibacterial activity of some medicinal plant extracts against these bacteria. Methods: Raw and processed meat samples (n = 60) were collected from abattoirs and local markets. S. aureus, E. coli O157: H7, and K. pneumonia were isolated, identified by phenotypic methods, and then confirmed by 16S rRNA gene sequencing. The antibacterial activity and spectrum of essential oils and spices powder of cumin, black seeds, cloves, cinnamon, and marjoram was determined against the isolated strains in this study by microbial count and well-diffusion techniques. Results: A total of 33 isolates have been identified as S. aureus, 30 isolates were identified as E. coli O157: H7, and 15 isolates were identified as K. pneumonia. S. aureus, E. coli O157: H7, and K. pneumonia could be detected in both fresh and processed food with higher prevalence in the processed meat. There was a significant decrease in microbial count in treated samples either with the spices powder or essential oils of the tested medicinal plants compared to control samples during storage time period. Furthermore, while the microbial count increased in the control samples, the microbial count decreased to reach zero in almost all treated samples with essential oils after 15 days of storage. Conclusion: S. aureus, E. coli O157: H7, and K. pneumonia are associated with food from animal sources, in either fresh or processed meat samples. The prevalence of them was higher in the processed meat than in fresh meat. The essential oils and spices powder of cumin, black seeds, cloves, cinnamon, and marjoram have an in vitro wide spectrum antibacterial activity with the highest antibacterial activity for the black seeds.