Bacteriophages against Salmonella Enteritidis in poultry (Proteon, Łódź): identification by phage-specific PCR, PFU count by the double agar overlay plaque assay — at least 6 × 10⁶ PFU/L in water for drinking
Commission Implementing Regulation (EU) 2025/1390, published on 16 July 2025, authorises until 5 August 2035 a preparation of four lytic bacteriophages PCM F/00069, PCM F/00070, PCM F/00071 and PCM F/00097 from the Łódź company Proteon Pharmaceuticals as a zootechnical additive reducing environmental contamination with Salmonella Enteritidis by poultry — only in water for drinking, at a minimum dose of 2 × 10⁶ PFU per bird per day. The authorisation holder must monitor the selection of phage-resistant Salmonella variants.
- Methods in the annex (details at the EU reference laboratory): identification — phage-specific PCR; phage count in the additive and in water for drinking — double agar overlay plaque assay (plaques, PFU). According to the EURL report (EFSA opinion of 2021) the method was single-laboratory validated and verified; further validation by the network of national reference laboratories was not needed. Liquid additive: ≥ 5 × 10⁷ PFU/mL, phages in a 1:1:1:1 ratio.
- Earlier EFSA data: five batches 1.14–3.23 × 10⁸ PFU/mL; endotoxins 12–1645 IU/mL (mean 528), determined with amebocyte lysate tests; shelf life 12 months at 2–10 °C, at 5 °C losses < 0.5 log after 12 months. The host strain S. Gallinarum PCM B/00111 is resistant to ciprofloxacin and streptomycin, but no viable cells of it were detected in 12 batches of the additive.
- Efficacy (EFSA opinion of 26 November 2024): in laying hens challenged with S. Enteritidis 012PP2014, Salmonella counts in boot swabs fell e.g. from 7.98 to 2.96 log10 MPN/g (day 48), in breeding hens from 7.74 to 3.50 log10 MPN/g. In an in vitro test on 72 S. enterica strains from poultry the phages inhibited 52 of 55 Enteritidis strains, 2 of 7 Typhimurium and none of 3 Infantis and 3 Virchow — EFSA drew no conclusions for other serotypes.
- The applicant withdrew the claim of improved zootechnical performance and the applications for ornamental birds and liquid complementary feed. Label: the additive may not replace standard hygiene conditions of rearing. The preparation is considered a potential skin and respiratory sensitiser.