Clustered Regularly Interspaced Short Palindromic Repeats Genotyping of Multidrug-Resistant Heidelberg Strains Isolated From the Poultry Production Chain Across Brazil.

subsp. serovar Heidelberg has been associated with a broad host range, such as poultry, dairy calves, swine, wild birds, environment, and humans. The continuous evolution of . Heidelberg raises a public health concern since there is a global dispersal of lineages harboring a wide resistome and virulome on a global scale. Here, we characterized the resistome, phylogenetic structure and clustered regularly interspaced short palindromic repeats (CRISPR) array composition of 81 . Heidelberg strains isolated from broiler farms ( = 16), transport and lairage ( = 5), slaughterhouse ( = 22), and retail market ( = 38) of the poultry production chain in Brazil, between 2015 and 2016 using high-resolution approaches including whole-genome sequencing (WGS) and WGS-derived CRISPR genotyping. More than 91% of the . Heidelberg strains were multidrug-resistant. The total antimicrobial resistance (AMR) gene abundances did not vary significantly across regions and sources suggesting the widespread distribution of antibiotic-resistant strains from farm to market. The highest AMR gene abundance was observed for , , , , , and for 100% of the isolates, followed by 88.8% for . The β-lactam resistance was essentially driven by the presence of the plasmid-mediated AmpC (pAmpC) gene, given the isolates which did not carry this gene were susceptible to cefoxitin (FOX). Most . Heidelberg strains were classified within international lineages, which were phylogenetically nested with strains from European countries; while CRISPR genotyping analysis revealed that the spacer content was overall highly conserved, but distributed into 13 distinct groups. In summary, our findings underscore the potential role of . Heidelberg as a key pathogen disseminated from farm to fork in Brazil and reinforce the importance of CRISPR-based genotyping for salmonellae. Hence, we emphasized the need for continuous mitigation programs to monitor the dissemination of this high-priority pathogen.