In vitro growth-inhibitory activity of plant extracts and phytochemicals against diarrhoea-associated and probiotic bacteria of veterinary importance

Diarrhoea is a common cause of morbidity and mortality of farm animals, especially during the pre-and post-weaning periods of youngs. Among others, bacterial infections are the leading causes of neonatal diarrhoea. Though antibiotics effectively prevent casualties, they often induce gut dysbiosis [1], [2]. Thus, it warrants searching for new alternatives that can inhibit the growth of pathogens without affecting beneficial gut bacteria. Therefore, this study aimed to evaluate the growth-inhibitory effects of 18 ethanolic plant extracts and 6 phytochemicals against 12 diarrhoea-associated bacteria, 6 bifidobacteria and 6 lactobacilli by the broth microdilution method following protocols of the CLSI [3] and Hecht (1999) [4] for aerobes and anaerobes, respectively. Extract of Embelia ribes fruits showed strong growth inhibitory activity against Bacillus cereus and Listeria monocytogenes with minimum inhibitory concentrations (MICs) of 64 and 128 µg/mL, respectively. It was only moderately toxic to 10 out of 12 probiotic bacteria (MICs ≥ 256 µg/mL). Besides, 8-hydroxyquinoline exhibited potent activity against Streptococcus bovis (MIC8 µg/mL) and 8 other infectious agents (MICs 32 µg/mL); and was weakly toxic to all the probiotic strains (MICs ≥ 128 µg/mL). Sanguinarine displayed strong effects in 3 pathogens (MICs 32 µg/mL). Results of 8-hydroxyquinoline and sanguinarine were in accordance with our previous research [5]. The study suggests that E. ribes extracts inhibited pathogens and had lesser toxic effects on probiotic bacteria. Thus, it may be of future veterinary importance to treat diarrhoea in farm animals, although animal trials are needed. We declare no conflict of interest.

 

Scroll to top

• References

• 1 Duan H, Yu L, Tian F. Antibiotic-induced gut dysbiosis and barrier disruption and the potential protective strategies. Crit Rev Food Sci Nutr 2022; 62 (06) 1427-1452
• 2 Holland RE. Some infectious causes of diarrhea in young farm animals. Clin Microbiol Rev 1990; 3 (04) 345-375
• 3 CLSI. Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically, 11th edition. CLSI Standard M07. Wayne: Clinical and Laboratory Standards Institute; 2018
• 4 Hecht DW. Antimicrobial Agents and Susceptibility Testing: Susceptibility Testing of Anaerobic Bacteria. In: Murray PR, Baron EJ, Pfaller MA, Tenover FC, Yolken RH. ed. Manual of Clinical Microbiology, 7th ed. Washington DC: American Society for Microbiology; 1999: 1555-1563
• 5 Kudera T, Doskocil I, Salmonova H. et al. In Vitro Selective Growth-Inhibitory Activities of Phytochemicals, Synthetic Phytochemical Analogs, and Antibiotics against Diarrheagenic/Probiotic Bacteria and Cancer/Normal Intestinal Cells. Pharmaceuticals 2020; 13: 233

Publication History

Article published online:
12 December 2022