6. CONCLUSIONS
The nasopharyngeal microbiome plays an important role in modulating the susceptibility to respiratory infections in infants and young children. However, due to the complexity of the pathogenetic mechanisms involved, the role of dysbiosis at the nasopharyngeal levels on the pathogenesis of viral infections is still not completely understood. Recent insights have shown that early negative changes in microbial community composition, due to exposure to noxious environmental factors, may constitute a heightened risk for severe RSV respiratory infection as well as bacterial superinfection, in both term and preterm infants [2,10,15,16]. An exaggerated and ineffective inflammatory response to infection, associated with delayed viral clearance and increased risk of recurrent wheezing in later life are also observed [22]. The risk of serious bacterial superinfection, low in infants with mild RSV bronchiolitis, becomes higher when hospital admission with intensive care is required [46-50]. The elevated antimicrobial-resistance observed during bacterial super infections mandates careful stewardship and avoidance of inappropriate antibiotic prescription. Antimicrobial treatment does not eradicate bacteria from the nasopharynx. The reduction in carriage is temporary, followed by a rapid replacement, with overgrowth of more resistant strains, newly acquired or previously masked by other organisms [2,8,54]. The finding that specific groups of microorganisms might be associated with protection against RSV infection and less disease severity [28] suggests that studies should be done to understand the mechanistic insight into the potential positive role of these species in disease prevention. Further studies are also needed to investigate the possible short and long‐term benefits of microbiome therapeutic manipulation and immune training with the goal of improving patient outcomes.