Antibiotic Exposure Prior to Respiratory Viral Infection is Associated with Disease Progression to Lower Respiratory Tract Infection in Allogeneic Hematopoietic Cell Transplantation Recipients

Background: Placebo-controlled trials of probiotics indicate a protective effect against severe respiratory virus disease in immunocompetent humans; pulmonary complications (including viral pneumonia) have been shown to be associated with low microbiome diversity. Murine studies demonstrate that Lactobacillus priming of the respiratory tract induces heterologous immunity, providing protection from lethal pneumovirus challenges. These findings provide the rationale to examine whether pre- or post-transplant antibiotic exposure increases risk of disease progression of respiratory viral infections (RVIs) after allogeneic hematopoietic cell transplantation (HCT).