Characterization of Escherichia coli strains from red deer (Cervus elaphus) faeces in a Mexican protected natural area

Abstract

Escherichia coli is a commensal bacterium from the human and animal intestinal microbiota; however, some strains may be pathogenic and can cause a wide range of intestinal and extraintestinal diseases. The presence of pathogenic strains in wild animals, such as deer, may constitute a risk for humans and other animals. Thus, the aim of this study was to determine the antimicrobial resistance (AMR), serotype, phylogenetic groups and virulence genes (VGs) of 22 E. coli isolates obtained from red deer faeces (Cervus elaphus). Results showed that most isolates (17/22) were susceptible to the antimicrobials assessed, whereas only five of them were resistant to some of the tested antimicrobials (mainly to β-lactamics, and to trimethoprim/sulphamethoxazole). Regarding the phylogenetic groups, 19 isolates belonged to the B1 group and three to the B2 group. The identified VGs corresponded to stx1 (17/22), stx2 (12/22), estA (12/22), bfpA (6/22), and eae (4/22). Interestingly, hybrid strains containing VGs that belonged to STEC and EPEC (stx1, stx2, bfpA (n = 2) and stx1, bfpA (n = 1)) and to STEC and ETEC (stx1, estA (n = 1), stx2, estA (n = 1), stx1, stx2, bfpA (n = 6) and eae, stx1, stx2, bfpA (n = 1)) pathotypes were found. The identified serotypes were O:H21, O70:NM, O91:NM, O5:NM, O:NM, O23:H16, O23:H25, O38:H25, O6:H34, O6:NT and O75:H9. This work represents the first insight of potentially pathogenic E. coli strains in red deer from Mexico, and it establishes the importance of deer strain characterization. Moreover, the high frequency (12/22) of hybrid strains found in this study, along with a presumably pathogenic potential profile, could represent an additional risk for humans and animals, therefore further investigations on this issue would be needed.