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Abstract
The occurrence and persistence of bacterial pathogens on food products could be partially attributed to increases in resistance/tolerance to antimicrobials that are commonly used during food production. Therefore, it is imperative to evaluate the effectiveness of these antimicrobials in controlling major bacterial foodborne pathogens. Here, the effect of 1) different organic acids, including formate, succinate, and fumarate, and 2) natural antimicrobials (coffee extracts), including citric acid, malic acid, quinic acid, and trigonelline were evaluated against different strains of Campylobacter, Salmonella and E. coli O157:H7. The minimum inhibitory (MIC) and bactericidal (MBC) concentrations were assessed for each antimicrobial. The antimicrobials were also evaluated against artificially contaminated chicken breast meat and lettuce. Each meat and lettuce sample were inoculated with ~8 log CFU/g of bacterial cocktails and immersed in solutions containing antimicrobials. Bacterial colony forming units (CFU) counts were determined by standard microbiological methods. Inhibitory concentrations of all antimicrobials used in chicken and lettuce decontamination assays were significantly different from those determined in culture. PAA and chlorine were superior to formate, succinate, and fumarate. However, PAA and chlorine, at the tested concentrations, were insufficient to eliminate the bacteria from the chicken breasts and lettuce matrices. It was found that trigonelline might be a promising natural antimicrobial candidate; however, further evaluation and optimization are required. Lastly, the prevalence of Campylobacter spp. isolated from chicken breast meat collected from retail stores in Georgia, USA was ~ 42%. Molecular analyses showed that isolates were diverse, belonging to important sequence types and carried virulence and antibiotic resistance genes. Taken together, the findings highlight 1) the need to optimize interventions to enhance the control of pathogenic foodborne bacteria, and 2) the advantage of exploring natural antimicrobials as an additional option in a tool kit of interventions.