Enteric-colonized Cronobacter spp. can disrupt the central nervous system without penetrating the host barriers

Cronobacter sakazakii is an opportunistic foodborne pathogen known to cause severe neonatal infections. However, its potential subclinical effects on neurodevelopment remain largely unexplored. Here, we report that intestinal colonization by Cronobacter can induce neurobehavioral alterations without breaching host barriers. Analysis of fecal microbiota from the children in GUSTO cohort revealed that Cronobacter abundance was significantly and positively correlated with their emotional reactivity, anxiety, affective, and depressive problem scores, suggesting an association between gut Cronobacter colonization and emotional dysfunction. Using a zebrafish larvae model, we demonstrated that enteric colonization by C. sakazakii ATCC 25944 triggered a distinctive bending phenotype and locomotor instability, indicative of central nervous system (CNS) disturbance. Multi-omics profiling revealed upregulation of genes related to circadian rhythm (e.g., per2, nr1d1, nr1d2) and neuropsychiatric markers (hint1), alongside metabolic dysregulation involving lipid classes linked to neurodegenerative stress. Random mutagenesis coupled with whole-genome sequencing identified modifier variants in genes associated with lipopolysaccharide (LPS) biosynthesis and fimbrial adhesion, which attenuated the neurotoxic phenotype. LPS isolated from wild-type C. sakazakii, but not from mutants, reproduced the CNS impairment phenotype, highlighting its crucial virulence role. Collectively, our findings provide the first evidence that enteric Cronobacter colonization may influence CNS integrity and emotional development via gut-derived LPS signaling, emphasizing its underestimated role in the gut-brain axis and neurobehavioral health.