Precision vs. Proclivity: An In Silico Comparison of AMR Emergence in Narrow and Broad-Spectrum Therapies

Background: The acceleration of antimicrobial resistance (AMR) is frequently associated with suboptimal prescribing patterns and the off-target effects of broad-spectrum agents. While broad-spectrum therapy offers immediate clinical coverage, the evolutionary cost to the commensal gut microbiota remains a critical concern for opportunistic infections and resistance emergence. Methods: This study employed a comparative in silico framework to evaluate the proteomic interactions of two broad-spectrum (Ciprofloxacin, Rifaximin) and two narrow-spectrum (Fidaxomicin, Metronidazole) antibiotics. Using bioinformatic tools, we analyzed binding affinities against primary gastrointestinal pathogen Escherichia coli versus resident "off-target" commensal proteins. Results: Preliminary modeling indicates that broad-spectrum agents exhibit high binding promiscuity across diverse commensal proteomes, significantly disrupting the homeostatic microbial balance. In contrast, narrow-spectrum agents demonstrated a localized "surgical" interaction profile, minimizing the selective pressure on the residual gut flora. Our results suggest that broad-spectrum-induced proteomic stress is a primary driver of the dysbiosis that precedes AMR. Conclusion: By mapping protein interaction pathways, this study provides a computational roadmap for evaluating drug-induced AMR risks. These findings advocate for a shift toward "narrow-spectrum first" stewardship to preserve the gut microbiome and provide a scalable bioinformatic protocol for screening future antimicrobial candidates.