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Significance and Impact of the Study: This study showed that condensed tannins (CTs), which were a group of secondary metabolites of many plants and rich in prodelphinidins (PD), had greater antibacterial activity against avian pathogenic Escherichia coli (APEC) than CTs that were rich in procyanidins (PC). The mode of action of the CTs was to inhibit the swimming and swarming motility of APEC, and its ability to form biofilms. The significance of this finding is that the use of PD-rich CTs to control APEC should not encourage the development of antibiotic resistance by APEC because a different mechanism is used. If confirmed in vivo, this could provide the poultry industry with a valuable and novel means of controlling the antibiotic resistance. AbstractCondensed tannins (CTs), which extracted from yew leaves, tilia flower and black locust leaves, were examined for their antimicrobial in vitro activity against avian pathogenic Escherichia coli (APEC). Past research demonstrated that CTs which contain procyanidins and prodelphinidins that could inhibit the growth of a wide range of bacteria. However, there is no information on how these affect pathogenic bacteria from chickens such as APEC. The high concentration of extracts, 10, 5, 2Á5 mg ml À1 , affected the growth curves of APEC, which gave different inhibition values for the three CT extracts. Furthermore, these CTs had significant effects (P ≤ 0Á05) on APEC biofilm and motility depending on each CT concentration and composition. However, at low concentration (0Á6 mg ml À1 ), the tilia flowers, a high molar percentage of procyanidins, enhanced bacterial cell attachment and improved the swimming motility of APEC. In contrast, yew, an equal molar percentage of procyanidins/ prodelphinidins, and black locust, a high molar percentage of prodelphinidins, interrupted and blocked swarming and swimming motility. The data suggested that the antimicrobial activity of the CT extracts was elicited by a positive relationship between anti-biofilm formation and anti-motility capacities.

Poultry provides an important protein source consumed globally by human population, and simultaneously, acts as a substantial reservoir of antibiotic resistant bacterial species such as Escherichia coli , Salmonella , Campylobacter , Clostridium perfringens . These bacterial species can include commensal strains with beneficial roles on poultry health and productivity, and pathogenic strains not only to poultry but zoonotically to man. This review paper evaluates the role of phytochemicals as possible alternatives to antibiotics and natural anti-bacterial agents to control antibiotic resistance in poultry. The focus of this paper is on the polyphenolic phytochemicals as they constitute the major group; carvacrol oil (the active ingredient of oregano), thymol oil (the main ingredient of oregano), oregano oil, and tannins oil as feed additives and their mechanism of actions that might enhance avian gut health by controlling antibiotic-resistant bacterial strains spread in poultry.

Although various meat and meat products may include various foodborne pathogens, meat is still an excellent source of nutrients compared to other foods. Due to bioactive materials, numerous plants and their extracts, including pomegranate, have been reported to possess antibacterial and antioxidant effects. Sixty fresh beef samples, bought from the local stores Karkh/ Baghdad, were properly divided into three similar groups; each group included 20 samples. The first group served as a control group, and it was soaked in distilled water. The second group was soaked in a 20g/L treatment dose of pomegranate pomace solution and was referred to as the treated group (T1). The third group was administered as 40g/L pomegranate pomace solution(T2). The results showed that the pomegranate pomace solution (T1 and T2) exhibited antimicrobial activity on the total bacterial count, lipid oxidation, and pH values. The current findings demonstrated that beef immersed into both concentrations of pomegranate pomace was more resistant to elevation in bacterial counting plus lower levels of peroxidation, measured using Thiobarbituric acid reactive substances plus fewer pH values compared to the control, as it was preserved for more days. The pomegranate pomace solutions might be utilized as natural preservatives of meat products, even at low concentrations.

Two different types of condensed tannins (CTs), which were extracted and purified from tilia (Tilia L.) and black locust (Robinia pseudoacacia), were studied and tested against two kinds of bacteria, including Gram-negative and Grampositive, avian pathogenic E. coli (APEC) and Staphylococcus epidermidis (S. epidermidis) respectively, by minimal bactericidal concentrations (MBCs) and scanning electron microscopy (SEM).Both CT extracts were significantly effective (P ≤ 0.05) at MBCs of 5 -10 mg CT/ml against APEC (Gram-negative), and at 1.25 -5 mg CT/ml on S. epidermidis (Gram-positive). This indicated that the CTs were more potent against the Grampositive than the Gram-negative bacteria. Further, SEM revealed that CTs caused mainly morphological deformations of the bacterial cells and some conjoined cell growth.