Microbiological status in preschool asthma: the VIRASTHMA 2 study

<b>Objective:</b> Describe the microbiological status during a severe asthma exacerbation and at steady state in preschool children (&lt;5 years). <b>Methods:</b> Multicenter prospective study (Hauts-de-France, France). 147 asthmatic children were included during an hospitalization for a severe exacerbation (2015-2018). Phenotype, atopic status, viral status (PCR, nasal swab sample), bacteriological status (culture, induced sputum) were assessed during the exacerbation and at steady state, 8 weeks later. <b>Results:</b> We observed a seasonal distribution of the inclusions (figure). During the exacerbation, a virus was identified in 94% (V+); rhinovirus (RV) in 74% (R+), more frequently in June (95%) and September (82%) (p&lt;10^-2); bocavirus in 14%; enterovirus in 10%; adenovirus in 8%; RSV in 8%. Bacteriological cultures (n=103) were positive (titer ≥ 10⁴/ml) for 57%: <i>H. influenzae</i> (38%), <i>M. catarrhalis</i> (26%), <i>S. pneumoniae</i> (19%). At steady state, 67% were V+, 51% R+. In total, 38% were R+ both at exacerbation and at steady state (R+R+). R+R+ children didn’t differ from others concerning phenotype, atopic status, positivity of bacteriological culture but were less exposed to mold/moisture (p=0.01). <b>Conclusion:</b> We confirm a high prevalence of RV infection during asthma exacerbations, frequently associated with bacteria. We now aim at exploring the host immune innate responses to these microorganisms.