Myxovirus resistance protein A to differentiate between viral and non-viral respiratory infections in adults: a prospective study

Objectives: To assess the diagnostic utility of Myxovirus resistance protein A (MxA) in differentiating between viral and non-viral respiratory infections in adults. Methods: This prospective, multicenter diagnostic accuracy study enrolled adults with acute respiratory infections (ARI) from outpatient and inpatient settings, alongside asymptomatic controls. Peripheral blood was collected for quantitative MxA measurement. Pathogen detection used targeted next-generation sequencing combined with conventional microbiological testing. Aetiological diagnoses were determined using standardized algorithms based on detected pathogens. The diagnostic accuracy of MxA for identifying viral ARIs was calculated. Results: Among 518 ARI patients, 325 had viral pathogens detected, 131 had bacterial/fungal pathogens, and 62 had no pathogen detected. Median MxA levels were significantly higher in viral (123.6 ng/ml; interquartile range [IQR], 56.4–189.6) than bacterial/fungal infections (15.9 ng/ml; IQR, 9.9–38.1; Bonferroni test p < 0.001) and controls (n = 158; 8.2 ng/mL; IQR,