Evaluation of a Novel Point-of-Care Blood Myxovirus Resistance Protein A Measurement for the Detection of Viral Infection at the Pediatric Emergency Department

Background. Prompt differentiation of viral from bacterial infections in febrile children is pivotal in reducing antibiotic overuse. Myxovirus resistance protein A (MxA) is a promising viral biomarker. Methods. We evaluated the accuracy of a point-of-care (POC) measurement for blood MxA level compared to the reference enzyme immunoassay in 228 febrile children aged between 4 weeks and 16 years, enrolled primarily at the emergency department (ED). Furthermore, we analyzed the ability of MxA to differentiate viral from bacterial infections. Results. The mean difference between POC and reference MxA level was -76 mu g/L (95% limits of agreement from -409 to 257 mu g/L). Using a cutoff of 200 mu g/L, POC results were uniform with the reference assay in 199 (87.3%) children. In ED-collected samples, the median POC MxA level was 571 (interquartile range [IQR], 240-955) mu g/L in children with viral infections, 555 (IQR, 103-889) mu g/L in children with viral-bacterial coinfections, and 25 (IQR, 25-54) mu g/L in children with bacterial infections (P < .001). MxA cutoff of 101 <mu>g/L differentiated between viral and bacterial infections with 92% sensitivity and 91% specificity. Conclusions. POC MxA measurement demonstrated acceptable analytical accuracy compared to the reference method, and good diagnostic accuracy as a biomarker for viral infections.