A Resistome Roadmap: From the Human Body to Pristine Environments.

Area of Science:

• Microbiology
• Genomics
• Public Health

Background:

• Antibiotic resistance genes (ARGs) pose a significant global health threat.
• A comprehensive understanding of the human body's resistome is lacking.
• The potential for ARG dissemination into environmental ecosystems requires investigation.

Purpose of the Study:

• To characterize the human body resistome across major body sites.
• To investigate the variability of antibiotic resistance genes (ARGs) between individuals and body sites.
• To assess the likelihood of ARG transfer from the human microbiome to pristine environments.

Main Methods:

• Analysis of 771 Human Microbiome Project samples from skin, nares, vagina, gut, and oral cavity.
• Identification and quantification of ARGs using proteomic data (9.1 × 10^7 proteins).
• Comparison of ARG profiles with environmental samples (271 samples, 2.1 × 10^8 proteins).

Main Results:

• Discovery of 28,714 ARGs across 235 types, with distinct profiles per body site.
• Nares exhibited the highest ARG load (5.4 genes/genome), while the gut had the lowest abundance (1.3 genes/genome).
• Fluoroquinolone, macrolide-lincosamide-streptogramin (MLS), and tetracycline resistance genes were most prevalent; ARG spread to pristine environments was rare.

Conclusions:

• The human body harbors a diverse resistome with significant inter-individual and body-site variability.
• Most identified ARGs pose a low risk, but specific high-risk ARGs were noted.
• Limited ARG transfer to pristine environments suggests a low immediate risk, supporting the One Health approach.