Sublethal antibiotics collapse gut bacterial populations by enhancing aggregation and expulsion

Area of Science:

• Microbiology
• Biophysics
• Gastroenterology

Background:

• Antibiotics cause significant, variable changes in the intestinal microbiome, even at sublethal concentrations.
• The precise mechanisms underlying these microbiome alterations remain largely unknown.

Purpose of the Study:

• To investigate the effects of sublethal antibiotic concentrations on intestinal microbial dynamics.
• To elucidate the mechanisms behind antibiotic-induced microbiome disruption.

Main Methods:

• Utilized gnotobiotic zebrafish for high-resolution observation of microbial dynamics.
• Administered sublethal doses of ciprofloxacin, a common antibiotic.
• Employed live imaging to track bacterial behavior and interactions.

Main Results:

• Sublethal ciprofloxacin caused substantial reductions in bacterial abundance.
• Disruption disproportionately affected slow-growing, aggregated bacteria compared to fast-growing, planktonic species.
• Antibiotic treatment enhanced bacterial aggregation and intestinal expulsion.

Conclusions:

• Intestinal mechanics amplify antibiotic effects on resident bacteria.
• Antibiotic-induced microbiome collapse can be modeled as a gelation phase transition.
• A biophysical framework can predict antibiotic impacts on the intestinal microbiome.