Impact of Early Antibiotic Exposure on Gut Microbiota Development in Preterm and Very Low Birth Weight Infants: Focus on Duration of Treatment

Preterm and very low birth weight (VLBW) infants are frequently exposed to antibiotics immediately after birth because of the high risk of early-onset sepsis. While antibiotic treatment can be life-saving, growing evidence indicates that early and prolonged exposure disrupts the developing gut microbiota, potentially leading to adverse effects on immune development, metabolism, and long-term health. However, the optimal duration of antibiotic use in this vulnerable population remains unclear, and clinical practices vary widely among neonatal intensive care units (NICUs).This study aims to clarify how different durations of early antibiotic administration affect gut microbiota development in preterm and VLBW infants. Using longitudinal stool samples collected during the neonatal period, we will analyze bacterial composition and diversity through 16S rRNA gene sequencing. Clinical data, including gestational age, nutritional factors, and infection status, will be integrated to evaluate the relationships between antibiotic exposure, microbiota maturation, and postnatal growth.By identifying microbial alterations associated with the length of antibiotic exposure, this research will provide important insights into balancing infection control with microbiota preservation. The findings could contribute to evidence-based strategies for antibiotic stewardship in neonatal care, ultimately promoting healthier growth and immune development in preterm infants.