Objective:

To evaluate the impact of nursery attendance on the gut microbiome composition of infants and the transmission of microbial strains among nursery peers, highlighting the significance of these interactions.

Key Findings:

• Infants acquired a greater proportion of gut microbial strains from nursery peers than from family members after 3 months, with nursery-derived strains accounting for nearly 40% of the infant gut microbiome by the end of the first term.

Interpretation:

The study highlights the significant role of nursery environments in shaping the gut microbiome of infants, suggesting that peer interactions may have a more substantial influence than family members after a short period of nursery attendance, with implications for nursery practices.

Limitations:

• Geographical limitation to a single Italian city may affect generalizability, particularly in diverse populations.
• Focus on dominant strains may underestimate transmission of low-abundance strains, potentially skewing results.
• Less frequent sampling of parents and educators may limit detection of adult-to-infant strain sharing, impacting the understanding of transmission dynamics.
• Observational design precludes causal inference, limiting the ability to draw definitive conclusions about the effects of nursery attendance.

Conclusion:

Nursery attendance significantly alters the gut microbiome of infants, with peer interactions playing a crucial role in microbial strain acquisition, emphasizing the importance of these environments in early development.