Livestock & aquaculture (AMR source control)
Intensive livestock and aquaculture are among the largest reservoirs driving antimicrobial resistance (AMR): poultry flocks shed nontyphoidal Salmonella into the food chain, while warm-water aquaculture relies heavily on antibiotics to combat Vibrio (shrimp acute hepatopancreatic necrosis disease/luminous vibriosis) and Aeromonas (motile aeromonad septicemia, furunculosis) outbreaks. Because these are open, high-volume production systems where blanket antibiotic prophylaxis both selects for resistant strains and contaminates water and meat, the priority is "source control" — knocking pathogen loads down at the farm/pre-harvest stage without adding to the resistome. Bacteriophages fit this niche well: they are self-amplifying, water- and feed-deliverable, leave a balanced commensal microbiota intact, and carry no antibiotic-resistance genes when properly screened, so they reduce pathogen burden and antibiotic demand rather than adding selective pressure. This is one of the most regulatorily mature phage applications, with products already authorized for poultry feed and salmon farming.
How phages act here
Mechanism
Lytic phages adsorb to specific surface receptors (LPS O-antigen, flagella, outer-membrane proteins) and lyse the host, so activity is strain/serovar-restricted — which is why multi-phage cocktails (e.g., Bafasal's four phages; broad-host-range Vibrio pairs) are used to cover S. Enteritidis/Typhimurium/Kentucky, V. harveyi/parahaemolyticus/diabolicus, and A. hydrophila/salmonicida and to suppress resistant mutants. In farm settings phages are delivered in drinking water, top-coated on feed, encapsulated for acid/gut stability, or dosed straight into tank/pond water as a biocontrol agent that holds pathogen density below disease thresholds during high-risk windows (transport, vaccination, grading). Documented effects include multi-log cecal/tissue and water-column reductions, lower mortality, reduced histopathology, and improved growth performance; therapeutically curated phages are screened to lack lysogeny, virulence, and AMR genes. Phage-antibiotic synergy and engineered/CRISPR-Cas "sequence-specific antimicrobial" approaches that resensitize or selectively kill resistant strains are active research angles but remain largely preclinical in this sector.
Where it stands
Current evidence
This indication has crossed from research into authorized commercial products. For poultry Salmonella, the EU formally authorized Proteon Pharmaceuticals' Bafasal — four bacteriophages delivered via drinking water — as the first bacteriophage-based zootechnical feed additive for all poultry, following a positive EFSA FEEDAP safety/efficacy opinion in 2024 (Regulation entered into force August 2025); Bafasal is also registered in India and Brazil. In the U.S., Intralytix's SalmoFresh phage cocktail has held FDA GRAS status (GRN 435) since 2013 for anti-Salmonella treatment of poultry, meat, fish, shellfish and produce, with later expansion to red-meat carcasses. In aquaculture, ACD Pharma (Norway) launched CUSTUS YRS, the world's first aquaculture phage product (2018), dosed into farm water against Yersinia ruckeri in Atlantic salmon, and is developing analogous products for other pathogens; feed majors (Skretting) and phage firms (Fixed Phage, Proteon) have active aquaculture programs. The Salmonella/Vibrio/Aeromonas evidence base is dominated by 2021–2025 controlled in-vivo challenge trials in broilers, shrimp postlarvae, and farmed fish (turbot, carp/tilapia/catfish) showing multi-log reductions and survival benefit, plus a few commercial deployments — but large multi-site field RCTs and harmonized regulatory pathways outside the EU/US are still maturing.
Evidence confidence: medium
The data
Key studies & trials
- Thanki AM, Hooton S, Whenham N, Salter MG, Bedford MR, O'Neill HVM, Clokie MRJ. A bacteriophage cocktail delivered in feed significantly reduced Salmonella colonization in challenged broiler chickens. Emerging Microbes & Infections. 2023;12(1):2217947. ↗
- Nabil NM, Tawakol MM, Samir A, Hassan HM, Elsayed MM. Evaluation of lyophilized bacteriophage cocktail efficiency against multidrug-resistant Salmonella in broiler chickens. BMC Microbiology. 2024;24(1):338. ↗
- Lomelí-Ortega CO, Barajas-Sandoval DR, Martínez-Villalobos JM, et al. A Broad-Host-Range Phage Cocktail Selectively and Effectively Eliminates Vibrio Species from Shrimp Aquaculture Environment. Microbial Ecology. 2022;86(2):1443-1446. ↗
- Muliya Sankappa N, Shivani Kallappa G, Kallihosuru Boregowda K, et al. Novel lytic bacteriophage AhFM11 as an effective therapy against hypervirulent Aeromonas hydrophila. Scientific Reports. 2024;14(1):16882. ↗
Who is working on it
Programs & centers
The possibility
Within the decade, phage dosing could become a routine, label-driven hurdle in poultry sheds and fish/shrimp farms — metered into drinking water, feed coatings, or pond intakes the same way probiotics are today — quietly shrinking antibiotic use and the AMR genes that flow from farm to fork. Region-specific "phage banks" matched to local Salmonella, Vibrio, and Aeromonas strains, refreshed against emerging resistance and possibly paired with CRISPR-guided or synergy-enhancing constructs, could let producers stay ahead of pathogens without ever reaching for a last-line antibiotic. As Bafasal's EU clearance and CUSTUS YRS demonstrate that regulators and industry will adopt phages at scale, livestock and aquaculture may become the first arena where phage biocontrol is simply standard agricultural practice.