Objective To investigate the prevalence of pathogenic Escherichia coli carried by wild animals in the Qinghai-Tibet Plateau. Fecal samples were collected from wild blue sheep, white-lipped deer, and red deer from Qinghai, as well as from a variety of bird faeces including the Himalayan vulture, red-billed chough, rock pigeon, and ruddy shelduck.

Methods A total of 237 faecal samples of wild animals and birds collecting in Qinghai in 2023 were subjected to selective isolation and cultivation of Escherichia coli using the EC broth enrichment method followed by ECC agar. The virulence genes of the isolates were detected through PCR. Furthermore, representative isolates were subjected to whole-genome sequencing and Escherichia coli pathotype characterization.

Results There were 169 strains in total were isolated from the feces of wild animals and birds in the Qinghai-Tibet Plateau, including Escherichia coli (n=60), Pantoea spp.(n=26), Pseudomonas spp.(n=23), Serratia spp.(n=16), and Enterobacter spp.(n=12). Based on the virulence genes carried by Escherichia coli, 46 strains were classified as different pathovars, with 33 strains being hybrid pathovars carrying multiple virulence genes, accounting for 55.00%, with the most common pathovar hybrids being a combination of two pathovars (38.33%). Through phylogenetic analysis, among the 60 strains of Escherichia coli, the predominant phylogroup belonged to B1 group (42/60), followed other phylogroups are A (5 strains), D (5 strains), B2 (4 strains), E (3 strains), and C (1 strain). All strains carried the gene fim, with over half of the strains carrying extraintestinal pathogenic Escherichia coli-related virulence genes, with positive rates of genes kpsD, aslA, and hlyA being 28.33%, 26.67%, and 26.67%, respectively, and positive rates of astA and stx (stx1, stx2) genes both being 23.33%. Three strains were positive for eae, with a low positivity rate (5.00%).

Conclusion Pathogenic Escherichia coli is widely present in wild animals such as blue sheep, white-lipped deer, red deer, and wild birds in the Qinghai-Tibet Plateau. Plateau wildlife serve as reservoir hosts for pathogenic E. coli, facilitating the discovery of various pathogenic types and phylogroup strains, thereby providing bacterial resources and scientific evidence for understanding the pathogenicity and epidemiological patterns of E. coli.