Food-producing animals are the major reservoirs for many foodborne pathogens such as Campylobacter species, non-Typhi serotypes of Salmonella enterica, Shiga toxin-producing strains of Escherichia coli, and Listeria monocytogenes. The zoonotic potential of foodborne pathogens and their ability to produce toxins causing diseases or even death are sufficient to recognize the seriousness of the situation. This manuscript reviews the evidence that links animals as vehicles of the foodborne pathogens Salmonella, Campylobacter, Shiga toxigenic E. coli, and L. monocytogenes, their impact, and their current status. We conclude that these pathogenic bacteria will continue causing outbreaks and deaths throughout the world, because no effective interventions have eliminated them from animals and food.

The use of natural compounds from plants can provide an alternative approach against food-borne pathogens. The mechanisms of action of most plant extracts with antimicrobial activity have been poorly studied. In this work, changes in membrane integrity, membrane potential, internal pH (pH _in ), and ATP synthesis were measured in V ibrio cholerae cells after exposure to extracts of edible and medicinal plants. A preliminary screen of methanolic, ethanolic, and aqueous extracts of medicinal and edible plants was performed. Minimal bactericidal concentrations (MBCs) were measured for extracts showing high antimicrobial activity. Our results indicate that methanolic extracts of basil ( Ocimum basilicum L.), nopal cactus ( Opuntia ficus-indica var. Villanueva L.), sweet acacia ( Acacia farnesiana L.), and white sagebrush ( Artemisia ludoviciana Nutt.) are the most active against V. cholera , with MBCs ranging from 0.5 to 3.0 mg/ml. Using four fluorogenic techniques, we studied the membrane integrity of V. cholerae cells after exposure to these four extracts. Extracts from these plants were able to disrupt the cell membranes of V. cholerae cells, causing increased membrane permeability, a clear decrease in cytoplasmic pH, cell membrane hyperpolarization, and a decrease in cellular ATP concentration in all strains tested. These four plant extracts could be studied as future alternatives to control V. cholerae contamination in foods and the diseases associated with this microorganism.

Quorum Sensing (QS), a signaling system present in bacteria, influences the expression of a variety of virulence factors. This study investigated the ability of citrus extracts to inhibit the activity of AI-2 molecules that mediate QS in Campylobacter jejuni and the effects of these extracts on motility, biofilm formation and expression of flaA-B. Cultures of C. jejuni were exposed to extracts of Citrus limon, Citrus medica and Citrus aurantium peels at various concentrations. Swarm motility tests were performed in Muller Hinton agar; biofilm formation was determined colorimetrically in microtiter plates; AI-2 activity was measured with a bioluminescence assay using V. harveyi; and flaA-B expression was determined by qRT-PCR. Treatment with C. limon or C. medica peel extract reduced swarm motility 44–59%, whereas treatment with C. aurantium extract reduced swarm motility 35–40%. Biofilm formation was reduced 60–75 % by these extracts, depending on extract concentration and /or strain tested. All three citrus extracts decreased AI-2 activity by about 90 %, and at 75 % of MBC, significantly (P ≤ 0.05) reduced expression of flaA-B. These findings provide preliminary metabolic and molecular insights into the effects of edible antimicrobials on QS and virulence factors of C. jejuni.