Outpatient Antibiotic Stewardship: A Growing Frontier—Combining Myxovirus Resistance Protein A With Other Biomarkers to Improve Antibiotic Use

Joseph, Patrick; Godofsky, Eliot

Combining MxA detection with a marker specific to bacterial infection, such as CRP, could be of greater predictive value and allow more reliable differentiation between viral and bacterial infections than using a marker of bacterial infection alone [7, 8, 24] . A high MxA with or without an elevated CRP would strongly suggest a viral infectious process and the absence of a bacterial infection [24] . Unlike the common occurrence of incidental identification of multiple pathogens in the OP or NP, true active co-infection that leads to a systemic viral and bacterial immune response is not common in URI [1, 8] . If both viral and bacterial pathogens are identified, an associated PCT ≥0.75 ng/mL or CRP ≥100 mg/L may support a diagnosis of a true co-infection result. Others have suggested that a defined ratio of CRP/MxA would optimize differentiation between a viral and bacterial infection [3] .