Researchers documented how amoxicillin treatment for ear infections disrupted gut microbiome assembly in infants, enriching antibiotic resistance genes and altering critical metabolites including short-chain fatty acids, bile acids, and amino acids. One infant received autologous fecal microbiota transplantation using their own pre-antibiotic stool, while another served as control. The transplant recipient showed convergence toward pre-antibiotic microbial composition and reduced β-lactam and tetracycline resistance genes, while the untreated infant remained persistently altered. This represents a paradigm shift in pediatric microbiome medicine. Early life represents the most critical window for gut ecosystem development, yet antibiotic use during this period has been linked to increased risks of asthma, allergies, and metabolic disorders later in life. The concept of banking an infant's own microbiome before antibiotic treatment offers unprecedented precision in restoration therapy. However, this case study's limitations are significant—only two subjects with one receiving intervention makes generalization impossible. The approach requires anticipating antibiotic need, limiting real-world application. Nevertheless, the integrated analysis of microbial composition, resistance genes, and metabolomics provides compelling mechanistic evidence for microbiome-targeted interventions during this vulnerable developmental period.