Genomic characterization of clinical and environmental isolates of Bacillus anthracis in Peru

Anthrax, or charbon, is a zoonotic disease caused by the Gram-positive bacterium Bacillus anthracis, responsible for sporadic outbreaks and representing a significant public health issue in Peru. In this study, 18 isolates from humans, animals and soil, collected between 2005 and 2017 across different country regions, were reactivated and analyzed. We identified antimicrobial resistance genes, virulence factors, plasmids, and their phylogenetic relationships using next-generation sequencing and bioinformatics tools. We detected eight genes associated with multidrug resistance, including vanZ-F, mphL, fosBgen, fosB, satA, bla, bla2, and fosB2. Additionally, 24 chromosomal virulence genes were identified, related to toxin production, capsule biosynthesis, secretion systems, and iron acquisition. Analysis of the pXO1 plasmid revealed the presence of 67 virulence-related genes, such as pagA, lef, cya, atxA, and pagR, while the pXO2 plasmid exhibited 24 genes, highlighting the cap genes associated with capsule synthesis. Phylogenetic analysis revealed that all strains belong to group A, subgroup A. Br. 003/004, providing valuable evidence about the evolutionary dynamics and genomic diversity of B. anthracis in Peru. These findings enhance our understanding of the genetic mechanisms involved in antimicrobial resistance and virulence, offering crucial insights for epidemiological surveillance and outbreak control.