Studying bacteriophage therapy in chickens

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Fowl typhoid (FT) is among the most significant poultry bacterial diseases worldwide, mostly affecting developing countries.¹ The causal agent of FT is Salmonella enterica Gallinarum. Although S enterica Gallinarum is egg-transmitted and produces lesions in chicks and poults, there is a much greater tendency to spread among growing or mature flocks. Mortality in young birds is possible but tends to be higher in older birds.²

In a poster presentation at the 2023 World Anti-Microbial Resistance Congress in Philadelphia, Pennsylvania, researchers from Purdue University in West Lafayette, Indiana, and the University of Veterinary and Animal Sciences (UVAS) Lahore, Pakistan, stated that, “Antibiotics are often used to prevent or control fowl typhoid; however, such practices contribute to the continually global challenge of antibiotic resistance.”¹

“In previous studies, we developed a polyphage prototype that significantly reduced Salmonella Gallinarum in experimentally challenged chickens. Here, we evaluated the pact of treatment with the polyphage prototype on microbial communities surrounding the targeted bacteria.”¹

The study

Day-old broiler chickens (50 males and 50 females) were randomly distributed into 5 treatment groups (n = 30 chickens) per group as below¹:

1. Chicken receiving no phage treatment or bacterial challenge
2. Chickens challenged with Salmonella Gallinarum
3. Chickens treated with encapsulated phages, challenged with Salmonella Gallinarum
4. Chickens treated with unprotected phages, challenged with Salmonella Gallinarum
5. Chickens treated with encapsulated and unprotected phages, challenged with Salmonella Gallinarum

The results

The results found:¹

1. Firmicutes were the most abundant phyla in chicken gut.
2. Cecal microbiota of chickens receiving a mixture of encapsulated and unprotected phage treated group showed similar but higher abundance of microbial communities to that of chickens receiving no challenge or phage treatment.
3. Phage treatment may enhanced the growth of beneficial communities such as Lactobacillaceae (lactic acid bacteria) and Lachnospiraceae bacteria.
4. A relatively higher abundance of lactobacillus fermentum and genus Streprococcus sop. in challenged chickens could be due to activation of an immune response and intestinal dysbiosis.

The researchers stated in conclusion, “The gastrointestinal microbiota plays a crucial role in the development of host immune system, health, and productivity. Our results indicated that beyond reducing targeted bacteria in the chicken, phage treatment may play beneficial role in modulation of chicken gut microbiota. Treatment with phages targeting Salmonella Gallinarum specifically may enhance the growth of beneficial gut microbiota in chicken and inhibit growth or potential opportunistic pathogens.”¹

Moving forward, bacteriophage therapy could be seen as an effective means to control FT without causing increases in antibiotic resistance.¹

References

1. Nazir I, Muktesh C, Devender A, et al. Impact of bacteriophage therapy against Salmonella Gallinarum on chicken gut microbiota. Presented at: World Anti-Microbial Resistance Congress. September 7-8, 2023; Philadelphia, Pennsylvania.
2. Davison Yeakel S. Fowl Typhoid. Merck Veterinary Manual. October 2022. Accessed September 8, 2023. https://www.merckvetmanual.com/poultry/salmonelloses/fowl-typhoid