An Intramuscular Multivalent Vaccine Against Pathogenic Escherichia Coli Injected in Suckling Piglets Reduced the Prevalence of Pathogenic E. Coli and Lawsonia Intracellularis Until Slaughter

Abstract Background: The present study aims to evaluate the efficacy of an intramuscular multivalent Escherichia coli vaccine for suckling piglets against infection not only by pathogenic E. coli but also by pathogens involved in Porcine Enteric Disease Complex (PEDC). Vaccinated Group had piglets vaccinated at days 10 and 20 of life with Colidex-C® (Vetia Animal Health, Spain), and Control Group had piglets that received sterile saline solution injection at the same days of life. We collected fecal samples in the farm from animals presenting diarrhea and intestinal mucosa swabs and ileum and colon tissue at slaughter and then performed PCR to identify E. coli virulence factors genes. Furthermore, we performed PCR to identify Lawsonia intracellularis, Brachyspira hyodisenteriae, and Salmonella spp.Results: Regarding fecal samples, 0% from Vaccinated Group was positive for E. coli, while Control Group had 94.1% of positive samples (p<0.0001). With respect to intestinal mucosa swab, 0% of the samples from Vaccinated Group were positive for E. coli, while 100% from Control Group were positive (p=0.001). Regarding ileum and colon tissue samples, 35% were positive for E. coli in Vaccinated Group and 85% in Control Group (p=0.001); Gcnt had a higher frequency of F41 (p=0.018), LT (p=0.018) and Sta (p=0.028) virulence factors genes. No sample was positive for Salmonella spp. nor for B. hyodisenteriae, but there were positive samples L. intracellularis; real-time PCR was performed and the frequencies found were 40% and 20% of ileum and colon positive samples in Vaccinated Group and 100% for ileum and 70% for colon in Control Group (p<0.001 for ileum and p=0.001 for colon).Conclusion: The results indicate that the E. coli vaccine for piglets may be a strategy to control E. coli infection. E. coli vaccines emerge as a probable strategy to help control L. intracellularis and, maybe, other enteric pathogens of pigs not evaluated in this study.