AUTHOR=De Maio Flavio , Buonsenso Danilo , Bianco Delia Mercedes , Giaimo Martina , Fosso Bruno , Monzo Francesca Romana , Sali Michela , Posteraro Brunella , Valentini Piero , Sanguinetti Maurizio 

TITLE=Comparative Fecal Microbiota Analysis of Infants With Acute Bronchiolitis Caused or Not Caused by Respiratory Syncytial Virus

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2022.815715

DOI=10.3389/fcimb.2022.815715

ISSN=2235-2988

ABSTRACT=<p>Bronchiolitis due to respiratory syncytial virus (RSV) or non-RSV agents is a health-menacing lower respiratory tract (LRT) disease of infants. Whereas RSV causes more severe disease than other viral agents may, genus-dominant fecal microbiota profiles have been identified in US hospitalized infants with bronchiolitis. We investigated the fecal microbiota composition of infants admitted to an Italian hospital with acute RSV (25/37 [67.6%]; group I) or non-RSV (12/37 [32.4%]; group II) bronchiolitis, and the relationship of fecal microbiota characteristics with the clinical characteristics of infants. Group I and group II infants differed significantly (24/25 [96.0%] versus 5/12 [41.7%]; <italic>P</italic> = 0.001) regarding 90% oxygen saturation (SpO<sub>2</sub>), which is an increased respiratory effort hallmark. Accordingly, impaired feeding in infants from group I was significantly more frequent than in infants from group II (19/25 [76.0%] versus 4/12 [33.3%]; <italic>P</italic> = 0.04). Conversely, the median (IQR) length of stay was not significantly different between the two groups (seven [3–14] for group I versus five [5–10] for group II; <italic>P</italic> = 0.11). The 16S ribosomal RNA V3–V4 region amplification of infants’ fecal samples resulted in 299 annotated amplicon sequence variants. Based on alpha- and beta-diversity microbiota downstream analyses, group I and group II infants had similar bacterial communities in their samples. Additionally, comparing infants having &lt;90% SpO<sub>2</sub> (<italic>n</italic> = 29) with infants having ≥90% SpO<sub>2</sub> (<italic>n</italic> = 8) showed that well-known dominant genera (<italic>Bacteroides</italic>, <italic>Bifidobacterium</italic>, <italic>Escherichia</italic>/<italic>Shigella</italic>, and <italic>Enterobacter</italic>/<italic>Veillonella</italic>) were differently, but not significantly (<italic>P</italic> = 0.44, <italic>P</italic> = 0.71, <italic>P</italic> = 0.98, and <italic>P</italic> = 0.41, respectively) abundant between the two subgroups. Overall, we showed that, regardless of RSV or non-RSV bronchiolitis etiology, no fecal microbiota-composing bacteria could be associated with the severity of acute bronchiolitis in infants. Larger and longitudinally conducted studies will be necessary to confirm these findings.</p>