Invited Speaker Australian Society for Microbiology Annual Scientific Meeting 2022

Silver gulls and Salmonella: microbial exchange at the human-wildlife interface (83035)

Bethany Hoye 1 2 , Max Cummins 3 4 , Steven Djordjevic 3 4 , Kimberley Maute 1 2 , Martina Sanderson-Smith 2 5
  1. School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, Australia
  2. Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, Australia
  3. Australian Centre for Genomic Epidemiological Microbiology, University of Technology, Sydney, NSW, Australia
  4. Australian Institute for Microbiology and Infection, University of Technology, Sydney, NSW, Australia
  5. School of Chemistry and Molecular Biosciences, University of Wollongong, Wollongong, NSW, Australia

Anthropogenic inputs are thought to drive the carriage of antibiotic resistance in free-ranging wildlife. However, the interplay between clinical and environmental microbial communities is not well understood. To better understand exchange between human and wildlife populations, we examined Salmonella enterica in the Illawarra region of NSW 2012-2019. Two hundered Salmonella genomes across 41 serovars were sourced from Silver gull chicks (Chroicocephalus novaehollandiae – a common, abundant, synanthropic species; n=99) and local clinical patients (n=101). We found no evidence of transmission within the gull colony, or persistence of isolates from one year to the next. However, 12 serovars were represented by both gull- and human-sourced genomes. By comparing these genomes with an additoinal 411 isolates from Enterobase that were closely related (<=HC5) to isolates from the Illawarra, we revealed extensive evidence of recent Salmonella transmission between gulls and humans, with gull-sourced isolates that were indistinguishable at a core genome level (i.e. shared an HC0 group) from clinical isolates from Australia and the UK. Carriage of pathogenicity islands, plasmids, IS elements and resistance genes was broadly related to serovar, but host-sepcific associations will also be discussed. Overall, our data suggest frequent microbial sharing between humans and wildlife, which, given the mobility of these wildlife hosts, threatens local antimicrobial stewardship efforts.