Bronchiolitis needs a revisit: Distinguishing between virus entities and their treatments

Jartti, Tuomas; Smits, Hermelijn H.; Bønnelykke, Klaus; Bircan, Ozlem; Elenius, Varpu; Konradsen, Jon R.; Maggina, Paraskevi; Makrinioti, Heidi; Stokholm, Jakob; Hedlin, Gunilla; Papadopoulos, Nikolaos; Ruszczynski, Marek; Ryczaj, Klaudia; Schaub, Bianca; Schwarze, Jürgen; Skevaki, Chrysanthi; Stenberg-Hammar, Katarina; Feleszko, Wojciech

As it comes to the microbiome of the airways, a diverse microbiological continuity exists between upper and lower airways. 32 The dramatic development of the microbiome of the airways begins at birth and is influenced by factors such as siblings, day-care attendance, antibiotics, and prior infections ( Figure 3 ). 33, 34 It has been speculated whether this low biomass compartment will obtain a steady colonization pattern over time. Recent studies have suggested that certain microbial colonization patterns prevalent already in early childhood may affect the risk of bronchiolitis and precede the development of persistent wheeze or asthma. 35 Furthermore, the severity of the acute respiratory infections may be modulated by the type of microbial community in the airways independent of RSV or RV coinfection, while at the same time, both RSV and RV may increase the severity of the infection independent of the bacteria. 34 It has also been shown that antibiotic treatment during acute wheezing episodes in childhood greatly decreases the duration of the symptoms, thus pointing toward microbial effects. 36 Likewise, a study of 1005 infants demonstrated that certain airway microbiota profiles seemed to increase the severity of bronchiolitis. 37 The rate of intensive care use and the length of hospital stay during the episode of acute bronchiolitis were particularly high in infants with a Haemophilus-dominant profile but low in infants with a Moraxella-dominant profile. This, although low in statistical power, was especially apparent in children with RSV bronchiolitis but not found for RV bronchiolitis. In a small randomized trial of 40 children hospitalized with RSV bronchiolitis, treatment with azithromycin during the acute episode seemed to alleviate the subsequent risk of long-term respiratory morbidity. 38 The microbiome of the human gut is shaped by an extensive Interactions between the two in bronchiolitis episodes may determine the severity various common as well as distinct unique pathogenic mechanisms.