Diversity of Non-O157 Shiga Toxin-Producing Escherichia coli Isolated from Cattle from Central and Southern Chile

• Published in: Animals (Basel) 2021-08, Vol.11 (8), p.2388
• Main Authors: Díaz, Leonela, Gutierrez, Sebastian, Moreno-Switt, Andrea I, Hervé, Luis Pablo, Hamilton-West, Christopher, Padola, Nora Lía, Navarrete, Paola, Reyes-Jara, Angélica, Meng, Jianghong, González-Escalona, Narjol, Toro, Magaly
• Format: Article
• Language: English
• Subjects: Animals; Antimicrobial agents; Antimicrobial resistance; Bioinformatics; Cattle; Disease; E coli; Epidemiology; Escherichia coli; Feces; Fermented food; Foodborne pathogens; Genes; Genomes; Health surveillance; Illnesses; Intimin; Laboratories; Manufacturers; non-O157; Outbreaks; Pathogens; Phylogeny; Public health; Reconstruction; Serotypes; Shiga toxin; Sorbitol; STEC; stx genes; Stx2 gene; Subgroups; Tellurite; Tellurium dioxide; Toxins; Virulence; virulence genes; Whole genome sequencing
• ISSN: 2076-2615; 2076-2615
• DOI: 10.3390/ani11082388

Cattle are the main reservoir of Shiga toxin-producing (STEC), one of the world's most important foodborne pathogens. The pathogen causes severe human diseases and outbreaks. This study aimed to identify and characterize non-O157 STEC isolated from cattle feces from central and southern Chile. We analyzed 446 cattle fecal samples and isolated non-O157 STEC from 12.6% (56/446); a total of 93 different isolates were recovered. Most isolates displayed β-glucuronidase activity (96.8%; 90/93) and fermented sorbitol (86.0%; 80/93), whereas only 39.8% (37/93) were resistant to tellurite. A subgroup of 30 representative non-O157 STEC isolates was selected for whole-genome sequencing and bioinformatics analysis. In silico analysis showed that they grouped into 16 different sequence types and 17 serotypes; the serotypes most frequently identified were O116:H21 and O168:H8 (13% each). A single isolate of serotype O26:H11 was recovered. One isolate was resistant to tetracycline and carried resistance genes and ; no other isolate displayed antimicrobial resistance or carried antimicrobial resistance genes. The intimin gene ( ) was identified in 13.3% (4/30) of the genomes and 90% (27/30) carried the gene. A phylogenetic reconstruction demonstrated that the isolates clustered based on serotypes, independent of geographical origin. These results indicate that cattle in Chile carry a wide diversity of STEC potentially pathogenic for humans based on the presence of critical virulence genes.