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 longāterm benefits of microbiome therapeutic manipulation and
immune training with the goal of improving patient outcomes.