In vitro antibacterial activity of plant extracts and phytochemicals in comparison with antibiotic growth promoters against intestinal pathogens of farm animals

From 2022, EU legislation prohibits using all forms of routine veterinary antibiotics, including antibiotic growth promoters (AGPs), for effective farm management of food-producing animals which necessitates searching for their new alternatives.

The purpose of this study was to compare growth-inhibitory effects of plant ethanolic extracts (n=20) and phytochemicals (n=4) with AGPs (n=7) using standard antibiotics (n=4) as positive control against 12 standard strains of gut bacteria relevant to farm infections by the broth microdilution method following the CLSI protocol.

Amongst tested plants, all three samples of Embelia ribes dried fruit extracts showed strongest inhibitory activity against Bacillus cereus and Listeria monocytogenes with minimum inhibitory concentrations (MICs) ranging from 32 to 128 µg/mL. Phytochemicals namely, 8-hydroxyquinoline and sanguinarine exhibited significant activity against 12 and 8 tested bacteria (MIC 32 – 128 µg/mL), respectively. In between AGPs, carbadox displayed significant activity against 11 tested microbes (MIC 4 – 64 µg/mL). Positive control ciprofloxacin showed substantial effects (MIC 0.0625 – 0.5 µg/mL) against all tested pathogens.

In case of phytochemicals, the results were in correspondence with our previous study [1].

In conclusion, E. ribes fruit extracts may have potent antibacterial activity of veterinary importance that need further investigation. Also, 8-hydroxyquinoline and sanguinarine appear promising leads to develop novel agents in this context, although animal trials are needed.

Publikationsverlauf

Artikel online veröffentlicht:
13. Dezember 2021

• References

• 1 Kudera T. et. al. Pharmaceuticals. 2020 13. 233 DOI: 10.3390/ph13090233