Different tissues from the chicken gut affect plasmid transfer in vitro

The emergence and spread of antibiotic resistance (AR) via bacterial plasmids lead to AR bacterial infections that pose a concern for animal and human health. The chicken gastrointestinal tract serves as a reservoir for AR gene transfer. An increasing incidence of resistance to last resort antibiotics in the gastrointestinal tract of chickens has been observed. An important aspect of the relationship between the gut microbiota and host health is the biogeography of the gut. However, the role of the gut environment in the transfer of AR genes remains unclear. We hypothesize that factors of the gut environment will affect the rate of plasmid transfer. Here we used chicken intestine explant models of the ilea, ceca, and colon to test plasmid transfer of antibiotic resistant plasmids from different incompatibility groups between E. coli strains. Our preliminary data show that chicken gut differentially promotes the transfer of plasmids from different incompatibility groups, and demonstrates the effect of biogeography. Interestingly, we found that supernatant following exposure to AR E. coli in ceca explants significantly increased the incidence of Inc.F plasmid transfer in in vitro conjugation assays. The specific mechanism by which conjugation is stimulated in chicken ceca explant supernatant after exposure to bacterium is currently under investigation. Overall, we demonstrate the use of chicken gastrointestinal explants as a model to study and elucidate the unique role of gut tissue in bacterial plasmid transfer and antibiotic resistance spread.

Key Words: chicken, antibiotic resistance, plasmid transfer, gut tissue explant, biogeography.

Presented at the 9th Symposium on Gut Health in Production of Food Animals, St. Louis, USA, 2021. For information on the next edition, click here.