Work

Genomic characteristics, antimicrobial resistance profiles and virulence factors of Gallibacterium anatis isolates from layer chickens in Northern China

Year: 2025

Type: article

Abstract: BACKGROUND: Gallibacterium anatis is an emerging pathogen causing substantial economic losses in global poultry production. Despite its growing clinical significance, the genomic basis of pathogenicity and antimicrobial resistance in this species remains poorly understood, particularly in China. RESULTS: We sequenced and analyzed five clinical G. anatis isolates from Chinese layer chickens alongside 31 global strains, their genomes ranged from 2.25 to 2.81 Mb with 39.8% average GC content. Phylogenetic analysis revealed that Chinese isolates cluster according to historical breeding stock importation patterns, reflecting international trade influences on pathogen distribution. Contemporary isolates showed extensive multidrug resistance compared to the antimicrobial-sensitive historical strain F149, with resistance profiles correlating directly with documented antibiotic usage in Chinese poultry production. Virulence analysis identified universal conservation of the RTX toxin system (97-100% prevalence) across all strains, contrasting sharply with variable distribution of other factors including fimbriae (30-35%) and secretion systems (50-60%). All strains harbored CRISPR-Cas systems, predominantly types I and III, indicating strain-specific phage defense adaptations. CONCLUSIONS: The RTX toxin system represents a core virulence mechanism and potential universal vaccine target for G. anatis. The rapid evolution from antimicrobial-sensitive to extensively resistant phenotypes demonstrates how global poultry trade accelerates both pathogen spread and resistance development. These findings provide molecular insights for targeted interventions against an increasingly problematic poultry pathogen.

Source: BMC Microbiology

DOI: 10.1186/s12866-025-04440-3