New insights regarding Acinetobacter genomic island-related elements

Area of Science:

• Microbiology
• Genomics
• Molecular Biology

Background:

• Genomic islands, such as Acinetobacter genomic island 1 (AGI1), play a crucial role in bacterial evolution and adaptation.
• Understanding the mobilization and distribution of these mobile genetic elements is essential for tracking the spread of antimicrobial resistance.
• Previous studies have focused on specific AGI elements, but a comprehensive analysis of related structures across diverse bacterial species is lacking.

Purpose of the Study:

• To mobilize the Acinetobacter genomic island 1-A (AGI1-A) from Enterobacter hormaechei.
• To investigate the distribution and structural diversity of AGI1-related elements within bacterial populations.
• To characterize the insertion sites and evolutionary relationships of these mobile genetic elements.

Main Methods:

• Mobilization of AGI1-A into Escherichia coli via conjugation.
• In silico analysis of whole-genome sequencing (WGS) databases to detect AGI backbones and variants.
• Comparative analysis of attachment (att) sites, recombination crossover points, and MDR region insertion sites.

Main Results:

• AGI1-A was successfully mobilized into E. coli, and its attachment site was characterized.
• AGI variants were detected in Salmonella enterica, Vibrio cholerae, E. hormaechei, Acinetobacter baumannii, E. coli, and Klebsiella pneumoniae.
• Two distinct AGI backbone groups were identified, and multidrug resistance (MDR) regions were inserted at five different lineages, indicating independent evolution.

Conclusions:

• AGI-related elements represent a diverse group of mobile genetic elements with distinct evolutionary trajectories.
• The independent evolution of AGI backbones and MDR region insertions contributes to their adaptability and spread.
• The classification of AGI-related elements into five groups (AGI1-AGI5) provides a framework for understanding their diversity and evolution.