Antimicrobial Effect of Garlic (Allium sativum) and Thyme (Zataria multiflora Boiss) Extracts on Some Food Borne Pathogens and Their Effect on Virulence Gene Expression

Abstract

The incrementing scope of pathogenic resistance to antibiotics has encouraged the search for antivirulence natural extracts. Therefore, our study designed to demonstrate the antimicrobial activity of an aqueous-garlic and thyme oil extracts against Gram-positive (Staphylococcus aureus) and Gram-negative (Salmonella spp.) bacteria by evaluating the influence of sub-inhibitory concentrations on the expression of the most critical virulence genes of the tested isolates.The antibacterial potential of both herbs was checked by the agar well diffusion method and minimum inhibitory concentration (MIC) assay. Interestingly, all isolates were inhibited by both extracts up to 50% concentration. Also, the MIC values of garlic extract (0.125-1µg/ml) against Salmonella isolates were lower than the values of thyme extract (0.5-8µg/ml). But in S. aureus isolates, the MIC values of thyme extract (0.25-2µg/ml) were the lowermost. Conventional PCR investigated that all S. aureus isolates carried the hlg (hemolysin) and icaA (intracellular adhesion) genes, but only six Salmonella isolates (three S. typhimurium and one each of S. kentucky, S. anatum, and S. lagos) had both the sopB (Salmonella outer protein B) and mgtC (membrane protein) genes. Real-time RT-PCR assays were performed to evaluate the extract's effect on the virulence genes. The thyme-oil extract has significantly repressed S. aureus virulence genes expression more than aqueous-garlic extract, which later one has effectively more than thyme-oil extract in downregulating the Salmonella virulence genes. In conclusion, garlic and thyme extracts can be used not only as a flavor, but also as potential antimicrobial agents against Gram-positive and negative bacteria.

Effects of phytogenic substances on growth and biofilm formation of Escherichia coli and Salmonella field isolates

“…The main compounds of the garlic oil used in the present study are diallyl disulfide and diallyl trisulfide. El-Azzouny et al (2018) demonstrated that aqueous garlic extract with its main compound allicin has a high antibacterial effect on Salmonella. Therefore, the differences in chemical composition, which resulted from different extraction procedures, may have high impact on the antibacterial efficacy of garlic extracts.…”

Characterization and antimicrobial potential of bioactive components of sonicated extract from garlic ( Allium sativum ) against foodborne pathogens

“…Moreover, inhibition of several bacterial enzymes such as trypsin and other proteases (Ifesan, Fadipe, & Ifesan, ) by allicin and other sulfur compounds has also been reported. Of these various reported compounds, allicin is the chief component (El‐Azzouny, El‐Demerdash, Seadawy, & Abou‐Khadra, ).…”

Immunomodulators for Curtailing COVID-19: a Positive Approach

“…Later demonstrations of its action against cytomegalovirus [109] and infectious bronchitis virus are also worth consideration [110]. Being a good antimicrobial, it has depicted significant effect against staphylococcus aureus, E. coli, campylobacter jejuni, streptococcus mutans, lactobacillus acidophilus and salmonella species [111,112,113,114,115]. In an interesting study aged garlic was found to have more potent antioxidant and antimicrobial activities than fresh one [116].…”