Prevalence and genomic characteristics of zoonotic gastro-intestinal pathogens and ESBL/pAmpC producing Enterobacteriaceae among Swedish corvid birds

Abstract

Introduction: Wild birds pose a potential threat to animal and human health by spreading infectious diseases. In the present study, we studied the occurrence of bacterial zoonotic pathogens as well as enterobacteria with transferrable antimicrobial resistance genes among Swedish corvids. Materials and methods: Intestines from 66 jackdaws, crows, rooks and magpies from the vicinity of livestock farms at 14 locations in 7 counties were analysed by direct culture or PCR screening followed by culture. Isolates were investigated by whole-genome sequencing. Results and discussion: Campylobacter jejuni were detected in 82% and Yersinia in 3% of the birds. ESBL-producing E. coli were found in one sample (2%) and carried bla _CTX-M-55. No Enterobacteriaceae with transferable carbapenem resistance were identified. No Salmonella or E. coli O157:H7 were found, but PCR analysis for enterohaemorrhagic E. coli virulence genes revealed 35% positive samples for intimin, 9% for verotoxin 1 and 17% for verotoxin 2. C. jejuni isolates from corvids were compared to previously published isolates from Swedish sources by multi-locus sequence typing based on genome sequences. All corvid C. jejuni isolates formed a cluster, intermingled with human and chicken isolates. Our results indicate that C. jejuni is ubiquitous among Swedish corvid birds, with sporadic transmission to poultry and humans.

Keywords: One health; campylobacter; genomics; jackdaw; wildlife; zoonotic disease.

Graphical abstract

Figure 1.

Approximate sampling locations (black dots) and the number of birds sampled at each location.

Figure 2.

Minimum spanning tree of MLST data from C. jejuni isolated from human cases of gastroenteritis, chicken farms and wild birds including corvids in Sweden (n = 1357). Distances of 1–3 loci are shown as solid lines, 4 loci as dashed lines.

Figure 3.

Minimum spanning tree of MLST data from C. jejuni isolated from human cases of gastroenteritis, chicken farms and wild birds including corvids in Sweden (n = 1357), showing species of wild birds for comparison with Figure 2.