Neonatal intensive care unit exposures reprogram microbiome–metabolome trajectories and modulate host calprotectin in preterm infants: a longitudinal multi-omics study

Early-life gut microbiota development is critical for orchestrating mucosal barrier function and immune priming, as disruptions in this process can increase susceptibility to life-threatening diseases such as necrotizing enterocolitis (NEC) and sepsis. This longitudinal multi-omics study of 186 preterm infants (<32 weeks of gestation or <1500 g birth weight) explores the impact of early-life exposures in the neonatal intensive care units (NICUs) on gut microbiota, metabolism, and immune responses. We analyzed 1153 stool samples using quantitative microbial profiling, untargeted metabolomics, and fecal S100A8/A9 (calprotectin) levels. Antibiotic exposure suppressed anaerobic colonization and microbial diversity in a cumulative exposure-dependent manner, with breastmilk feeding partially mitigating these effects. The stool metabolome correlated with microbial colonization, showing antibiotic-driven disruptions in polyamine metabolism linked to anaerobe abundance. Host calprotectin levels followed a biphasic pattern, correlating with microbial diversity and polyamine metabolites. Mediation analysis identified anaerobe suppression and polyamine depletion as key drivers of antibiotic-associated reductions in calprotectin. This study reveals that NICU interventions, particularly antibiotics, reprogram the preterm gut ecosystem and immune response, with anaerobes and polyamines being key mediators linking microbial ecology to immune maturation during early life.