Abstract
Background: Salmonella is a major food-borne bacterial pathogen that causes food poisoning related to the consumption of eggs, milk and meat. Food safety in relation to Salmonella is particularly important for eggs because their shells as well as their contents can be a source of contamination. Chicken can also be infected with influenza virus, but it remains unclear how co-infection of Salmonella and influenza virus affect each other. Aim: The potential influence of co-infection of Salmonella and influenza virus was examined.
Methods: Salmonella Abony and influenza virus were injected into chicken embryonated eggs. After incubation, proliferation of Salmonella and influenza virus was measured using a direct culture assay for bacteria and an enzyme-linked immunosorbent assay (ELISA) for influenza virus, respectively.
Results: Our findings indicate that the number of colony forming units (CFUs) of Salmonella did not vary between chicken embryonated eggs co-infected with influenza A virus and Salmonella-only infected eggs. Furthermore, we found the proliferation of influenza A or B virus was not significantly influenced by co-infection of the eggs with Salmonella.
Conclusion: These results suggest that combined infection of Salmonella with influenza virus does not affect each other, at least in the terms of their proliferation.

Key words: Co-infection, Combined infection, Influenza virus, Salmonella, Secondary infection