Abstract:
Faecal carriage of extended-spectrum cephalosporin-resistant (ESC-R) Enterobacterales in
healthy pets is a concerning issue. This study aimed to determine the prevalence, genetic background,
and potential for interspecies transmission of these bacteria between dogs and humans within the
same household (HH) or shelter environment in Romania. Faecal samples (n = 263) collected from
healthy dogs (n = 102), their owners (n = 32), as well as dogs (n = 110) and staff (n = 19) from dog
shelters, were screened for ESC-R carriage. Clonal relatedness of canine and human Escherichia
coli isolates was established using Fourier Transform Infrared Spectroscopy (FTIR), followed by
Illumina WGS of selected isolates. The highest prevalence of ESC-R Enterobacterales faecal carriage
was identified in staff working at dog shelters (78.9%), followed by dogs from households (44.11%),
dog owners (43.7%), and dogs from shelters (27%). FTIR identified 15 clusters of closely related E. coli
isolates, including dog and human isolates from the same environment. Co-carriage of ESC-R isolates
in both the dog and owner was identified in 12 HHs (37.5%), with two HHs (6%) having both the
owner and dog carrying isolates with identical FTIR spectra, phylogroup, resistance genes, and Inc
plasmids. Major ExPEC lineages such as ST127, ST10, ST155, and ST88 were detected in human and
dog isolates. Our study revealed a high prevalence of faecal ESC-R E. coli carriage in both dogs and
humans from Romanian households and shelters, where bidirectional clonal transmission between
humans and dogs is likely. Furthermore, we identified ESC-R Enterobacterales co-carriage in people
and dogs sharing the same environment using FTIR, demonstrating its value in AMR surveillance for
humans and animals.
