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

TL;DR

This study analyzes the genomes of Bacillus anthracis isolates in Peru, revealing genetic similarities, resistance genes, and virulence factors important for anthrax outbreaks.

Contribution

This is the first genomic characterization of B. anthracis in Peru, identifying multidrug resistance and virulence genes in clinical and environmental isolates.

Findings

All 18 isolates belong to group A, subgroup A.Br.003/004, showing high genetic similarity.

Eight multidrug resistance genes and 24 chromosomal virulence genes were identified.

pXO1 and pXO2 plasmids contain key virulence genes related to toxin production and capsule synthesis.

Abstract

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, fosB_gen, 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.

Anthrax, or charbon, is a severe disease that causes sporadic outbreaks in endemic regions of northern and central Peru, affecting both animals and humans. This study presents the first genomic characterization analysis conducted in Peru, based on isolates collected between 2005 and 2017. It provides valuable insights into the genetic relationships between isolates, clinically significant antimicrobial resistance genes, and virulence genes, suggesting the presence of multiple pathogenicity mechanisms. In this study, 18 isolates were reactivated and sequenced to genetically characterise Peruvian strains of Bacillus anthracis. Using bioinformatics tools, we found that all isolates exhibited high genetic similarity. Additionally, genes associated with resistance to certain antibiotics, important in public health and genes involved in toxin production and immune system evasion were identified. This summary highlights key findings that contribute to understanding the genetic mechanisms underpinning the pathogenicity and resistance of B. anthracis in Peru, providing a foundation for improved epidemiological surveillance and disease control strategies.

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