Antimicrobial in vitro activities of condensed tannin extracts on avian pathogenic Escherichia coli

• Published in: Letters in applied microbiology Vol. 70; no. 3; pp. 165 - 172
• Main Authors: Dakheel, M.M., Alkandari, F.A.H., Mueller‐Harvey, I., Woodward, M.J., Rymer, C.
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.03.2020
• Subjects: Animals; Anti-Bacterial Agents - pharmacology; Antibacterial activity; Antibiotic resistance; Antibiotics; Antimicrobial activity; Antimicrobial agents; antimicrobials; avian pathogenic Escherichia coli; Bacteria; biofilm; Biofilms; Biofilms - growth & development; Cell adhesion; Chickens - microbiology; condensed tannins; Drug resistance; E coli; Escherichia coli; Escherichia coli - drug effects; Escherichia coli - growth & development; Escherichia coli Infections - drug therapy; Escherichia coli Infections - veterinary; Escherichia coli Proteins - metabolism; Flowers; Growth curves; Leaves; Metabolites; Microbial Sensitivity Tests; Mode of action; Motility; Plant Extracts - pharmacology; Poultry; Poultry - microbiology; Poultry Diseases - drug therapy; Poultry Diseases - microbiology; Proanthocyanidins - pharmacology; Procyanidins; Secondary metabolites; Swarming; Swimming; Tannins; Virulence; Yew; avian pathogenic Escherichia coli; motility; condensed tannins; antimicrobials; biofilm
• ISSN: 0266-8254; 1472-765X
• DOI: 10.1111/lam.13253

Condensed 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, 2·5 mg ml−1, affected the growth curves of APEC, which gave different inhibition values for the three CT extracts. Furthermore, these CTs had significant effects (P ≤ 0·05) on APEC biofilm and motility depending on each CT concentration and composition. However, at low concentration (0·6 mg ml−1), 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. 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. 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.