The chestnut industry generates a large amount of by-products. These agro-industrial wastes have been described as potential sources of phenolic compounds with high bioactive potential. Therefore, we aimed to extract the phenolic compounds from chestnut by-products and assess their antioxidant potential and evaluate their antimicrobial activity against multidrug resistant bacteria. The individual phenolic compounds in the ethanolic extracts of chestnut shell, inner shell, bur, and leaves were characterized by HPLC-DAD/electrospray ionization (ESI)-MS. The antioxidant properties were determined by DPPH and ABTS assays. The minimum inhibitory concentration (MIC) and the antimicrobial susceptibility was performed using the Kirby–Bauer disc diffusion method against 10 bacterial strains. The major phenolic compounds identified in the extracts were trigalloyl-HHDP-glucose, gallic acid, quercetin, and myricetin glycoside derivatives. All chestnut by-products presented promising antioxidant activity in both assays, with leaf samples the ones presenting the highest antioxidant capacity. The inner shell’s extract was effective against all Gram-positive and two Gram-negative bacteria; nevertheless, all extracts showed antibacterial activity. Staphylococcus epidermidis showed susceptibility to all extracts while none of the extracts was able to suppress the growth of Escherichia coli and Salmonella enteritidis. Chestnut by-products are a source of phenolic compounds with prominent antioxidant and antimicrobial activities. Nevertheless, further studies should be conducted to assess the correlation between phenolic compounds and the bioactivities obtained.

Escherichia coli are one of the most important pathogenic bacteria readily found in the livestock and widely studied as an indicator that carries drug-resistant genes between humans, animals, and the environment. The use of antimicrobials in the food chain, particularly in food-producing animals, is recognized as a significant contributor to the development and spread of antimicrobial resistance (AMR) and resistance genes can be transferred from the farm through the food-chain. The objective of this review is to highlight the background of the antimicrobials use in food-producing animals, more specifically, to study clonal lineages and the resistance profiles observed in E. coli, as well as in extended spectrum beta-lactamases (ESBL) producing E. coli, in a set of food-production animals with greater relevance in food consumption, such as pigs, poultry, cattle, fish farming and rabbits. Regarding the prevalence of ESBL-producing E. coli among farm animals, high-to-moderate prevalence was observed, and the highest resistance rates to tetracycline and ampicillin was detected in different farms in all geographic regions. Worldwide pandemic clones and high-risk zoonotic E. coli clones have been identified in most food-producing animals, and some of these clones are already disseminated in different niches, such as the environment and humans. A better understanding of the epidemiology of E. coli and ESBL-producing E. coli in livestock is urgently needed. Animal production is one of the major causes of the antibiotic resistance problem worldwide and a One Health approach is needed.