Dust sprinkling as an effective method for infecting chickens with wild-type Salmonella Typhimurium and changes in host gut microbiota

Authors: KHAN, SAMIULLAH - University Of Adelaide; MCWHORTER, ANDREA - University Of Adelaide; ANDREWS, DANEIL - Bioproperties Pty Ltd; UNDERWOOD, GREGORY - Bioproperties Pty Ltd; MOORE, ROBERT - Royal Melbourne Institute Of Technology University; Gast, Richard; CHOUSALKAR, KAPIL - University Of Adelaide

Submitted to: Environmental Microbiology Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/2024
Publication Date: 5/5/2024
Citation: Khan, S., Mcwhorter, A., Andrews, D.M., Underwood, G.J., Moore, R.J., Gast, R.K., Chousalkar, K.K. 2024. Dust sprinkling as an effective method for infecting chickens with wild-type Salmonella Typhimurium and changes in host gut microbiota. Environmental Microbiology Reports. vol 16,(3). https://doi.org/10.1111/1758-2229.13265.
DOI: https://doi.org/10.1111/1758-2229.13265

Interpretive Summary: The role played by dust in Salmonella transmission on chicken farms is not thoroughly understood. The present study investigated Salmonella Typhimurium infection of egg-type chickens via contaminated dust. Contaminated dust was administered to chicks by either sprinkling onto their pens or by direct oral inoculation. Both inoculation methods resulted in colonization of the gut, but dust sprinkling led to higher Salmonella numbers in livers than oral inoculation. Infection of chickens using the sprinkling method at a range of doses showed a threshold for gut and organ colonization as low as 1000 colony forming units of bacteria per g of dust. Post-challenge analysis of the diversity of cecal microbes indicated similar profiles for chickens infected by the two dust administration routes, although both dust challenges induced differences in comparison to the uninfected negative controls. Overall, the study showed that dust sprinkling was a highly effective way to experimentally colonize chickens with Salmonella and alter the gut microbiota. These data also suggest a potentially important role for dust in the ability of Salmonella Typhimurium to colonize chickens in commercial settings.

Technical Abstract: The role dust has in Salmonella transmission on chicken farms is not well characterized. Salmonella Typhimurium infection of chickens using contaminated dust was investigated by both sprinkling dust onto pens of chicks and by oral inoculation. The Salmonella load in liver samples was significantly higher in the sprinkled dust infected group compared to the oral infection group, while both inoculation methods resulted in colonization of the gut. Infection of layer chickens using the sprinkling method at a range of doses showed a threshold for colonization of the gut and organs as low as 1000 CFU/g of dust. Cecal content microbiota analysis post challenge showed that the profiles of chickens infected by the sprinkling and oral routes were not significantly different; however, both challenges induced differences when compared to the uninfected negative controls. Overall, the study showed that dust sprinkling was a more effective way to experimentally colonize chickens with Salmonella and alter the gut microbiota than oral gavage of dust at levels as low as 1,000 CFU/g dust. These data suggest that dust plays a significant role in the ability of Salmonella Typhimurium to colonize chickens. Further examination using this model should allow us to explore the mechanisms underlying this interaction with the goal of exploring this response to maximize vaccine uptake and efficacy.