Salmonella Infantis is a tough opponent
Salmonella Infantis is the Salmonella serovar that most affects broilers in Europe
19 November 2024
2 minute read
By: [Excerpts of a presentation by Claudia Hess, DVM, University of Veterinary Medicine Vienna, during the Second International Avian Influenza Summit, held at the University of Arkansas, USA]
Salmonella Infantis (SI), is prevalent in the European Union, being the most common Salmonella serovar in broilers (95% of isolates being broiler-related) and the fourth most common in terms of human infections with salmonellosis. Once SI is established in a poultry house, it is very difficult to eradicate.
The pESI strains of SI are more virulent and better adapted to fast-growing broilers, posing a significant threat to both animal and human health, as they are multi-resistant to antibiotics.
The pESI positive strains can be detected early and are excreted by high shedding birds, while pESI negative strains are detected later and are excreted by low shedding birds. The pESI positive strains colonize all of the birds’ organs, while pESI negative strains are only detected in the ceca. Fast-growing broilers show high shedding and colonization, while layers show less colonization.
Disinfectant effectiveness
Research shows that while some disinfectants are effective, many require increased concentrations to be efficacious. An in vitro study tested disinfectants using different concentrations, temperatures, and degrees of contamination. Disinfectants were tested against seven selected SI strains, including non-persistent and persistent strains, and a Russian strain resistant to many antibiotics. The disinfectants tested were those which are mainly used in poultry farms and slaughterhouses in Europe.
Results of the study demonstrated that three disinfectants showed good activity against SI at manufacturer recommended concentrations, (1 – aldehyde and quaternary ammonium, 2 – peroxide, 3 – cresol) while other disinfectants required increased concentrations to be effective.
While there was no significant influence of environmental temperature on disinfectant efficacy, high contamination levels significantly reduced the efficacy of disinfectants which allowed for the revitalization of SI after disinfection. When there were high SI contamination levels, after 24 to 72 hours SI was reestablishing itself.
Based on the study, it is necessary to increase the concentration of some disinfectants to improve their efficacy against SI. The study also verified that poultry houses with high levels of contamination are harder to clean and disinfect which allows for a rapid revitalization of Salmonella Infantis. European Union poultry producers are known to be extremely meticulous in carrying out house cleaning and disinfection between flocks, and yet Salmonella Infantis just keeps coming back.
