Azithromycin therapy during respiratory syncytial virus bronchiolitis: Upper airway microbiome alterations and subsequent recurrent wheeze

Respiratory microbiota and lower respiratory tract disease

“…74 In a randomized controlled trial in infants with RSV-bronchiolitis admitted to hospital, Zhou et al assessed the effect of a 14-days course of azithromycin (AZM) on future recurrent wheezing, reporting a 50% reduction over the following 12 months. 69 Nasal lavages samples were taken before and after the treatment showing a significantly higher reduction in Moraxella relative abundance in the treatment group. Cautiously, the authors recognized difficulties unfolding the direct anti-inflammatory effect of AZM on respiratory airways and the indirect effect through Moraxella depletion on the recurrent wheezing reduction.…”

“…3 A total of 25 articles were retained for this section, 13 in adults, [46][47][48][49][50][51][52][53][54][55][56][57][58] and 11 in children. 19,[59][60][61][62][63][64][65][66][67][68][69] An overview of the studies characteristics is summarized in tables 2 (adults) and 3 (children).…”

“…We retrieved six original papers assessing the respiratory microbiota in infants with bronchiolitis, and one in children and adolescents with asthma, with all of them using upper airways samples. 19,[59][60][61][62]64,69 The article on asthma was included because it focused on the infectious component of recurrent wheezing pathophysiology. Despite a smaller variability in study population and in sampling sites than in the aforementioned pneumonia studies, findings in this condition are discordant.…”

“…Most studies associate Proteobacteria (phylum) and Moraxella or Haemophilus (genera) dominant taxa in upper respiratory microbiota with asthma, bronchiolitis or severity of bronchiolitis. 19,59,62,69 On the other hand, in a case-control study with infants with bronchiolitis and healthy controls, Hasegawa et al described four distinct profiles of upper respiratory microbiota, each of them dominated by a taxon, with infants with the Moraxella dominant profile having the lowest risk of having bronchiolitis, and the Staphylococcus dominant profile presenting an odds ratio of 5 for bronchiolitis. 60 Interestingly, Dolosigranulum dominant profile also presented a very low risk of bronchiolitis, consistent with the findings we described above in the section dedicated to pneumonia.…”

“…Four studies reported data on viral etiology and suggested virus-bacteria interactions in the pathogenesis of bronchiolitis and future recurrent wheezing, particularly between Proteobacteria and RSV. 19,62,69 The chronology of the interaction, i.e., whether a viral infection alters the epithelium environment allowing for a greater bacterial adherence or a colonizing bacteria predisposes to viral infection, is still unclear, although there is some evidence supporting the former at least in case of human rhinovirus infection (hRV). In a prospective study with weekly nasal samples collected from children aged four to twelve years old, detection of hRV increased the risk of concurrent or subsequent detection of pathogenic bacteria (either S. pneumoniae, H. influenzae or M. catharralis), whereas the opposite was not observed.…”