SUMMARY
  • Salmonella spp. are dangerous foodborne bacteria that can cause diarrhoea, vomiting, nausea, fever and abdominal pain in humans. The majority of Salmonella cases are linked to food items such as eggs and chicken.
  • This work shows that the efficacy of live salmonella vaccines is not inhibited by Orego-Stim® at working concentrations.
BACKGROUND
  • In the UK, under assurance standards such as the Lion Egg Code, mass vaccination programmes have contributed to a significant reduction in the number of incidences of salmonellosis in humans.
  • Orego-Stim® is a high quality, eubioitic containing 100% natural oregano essential oil.
TRIAL DESIGN

An independent trial was carried out with APHA, UK, to understand the effect of Orego-Stim on 4 salmonella vaccine strains and 2 wild-type field strains using broth microdilution methodology as recommended by EUCAST. Each strain was repeated 3 times and the average used for reporting. The recommended inclusion for Orego-Stim® 150ml per 1000L (equates to 1:6400 dilution). For Minimum Inhibitory Concentration (MIC) determination, a starting concentration of 1:100 was chosen, with serial dilutions in Mueller Hinton broth down to 1:12800.

Strains tested

  1. Salmonella Enteritidis – AviPro Duo Vac E (Elanco, USA)
  2. Typhimurium – AviPro Duo Vac T (Elanco, USA)
  3. Enteritidis – Salmovac 440 (IDT, Germany)
  4. Gallinarum – Nobilis SG 9R (MSD Animal Health, UK)
  5. Typhimurium DT104 – S04268-18 – field isolate
  6. Enteritidis PT4 – S04657-18 – field isolate
RESULTS

results table

*Green boxes indicates no visible growth inhibition; pink boxes indicate visible growth inhibition

  • No effect of Orego-Stim® was seen at any concentration on Salmovac 440 (Strain 3), R9 Nobilis (Strain 4) and field isolates (Strains 5 and 6).
  • The only inhibition observed was against the AviPro Duo VacE (Strain 1) and VacT (Strain 2), and this was only at the highest concentration of Orego-Stim® (1:100) representing an inclusion of 10L per 1000L (more than 60 times stronger than the recommended dose of 150ml per 1000L of drinking water).
  • It is recommended that manufactures guidelines are followed for vaccination administration and to flush drinking lines before vaccinating to ensure all birds receive a full dose of vaccine.
  • When vaccinating through the drinker lines (with any vaccine) the addition of Orego-Stim® into a stock solution containing vaccine for a dosing device is not recommended.