Conjugative transfer of streptococcal prophages harboring antibiotic resistance and virulence genes

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Prophages are known to transfer functional traits, but their role in transmitting antimicrobial resistance genes (ARGs) is debated.
• Streptococcus species are significant human pathogens, and understanding ARG dissemination is crucial for public health.

Purpose of the Study:

• To characterize a prevalent family of prophages in Streptococcus, termed SMphages.
• To investigate the antimicrobial resistance genes (ARGs) harbored by SMphages and their transmission mechanisms.

Main Methods:

• Characterization of SMphage genomes, including identification of ARGs and integration sites.
• Analysis of SMphage integration and excision mechanisms.
• Validation of SMphage-encoded surface protein virulence using cell and animal models.
• Investigation of SMphage transfer via conjugation, including the role of integrative and conjugative elements.

Main Results:

• SMphages harbor twenty-five ARGs conferring resistance to ten antimicrobial classes, including vancomycin (vanG) and oxazolidinone (optR).
• SMphages integrate into four chromosomal sites via three integration modules and can be induced to excise.
• Four subtypes of Alp-related surface proteins encoded by SMphages exhibit lethal effects in vitro and in vivo.
• High-frequency conjugation facilitates SMphage transfer, aided by integrative and conjugative elements.

Conclusions:

• SMphages are a significant factor in the widespread dissemination of ARGs within the Streptococcus genus.
• The identified ARGs and virulence factors contribute to the adaptability and pathogenicity of Streptococcus.
• Understanding SMphage biology is key to combating antimicrobial resistance in these important bacterial pathogens.