Developing a Tool for Differentiation Between Bacterial and Viral Respiratory Infections Using Myxovirus Resistance Protein A and C-Reactive Protein.

INTRODUCTION: The aim was to assess the performance of a blood assay combining measurements of MxA (myxovirus resistance protein A) and CRP (C-reactive protein) to differentiate viral from bacterial respiratory infections. METHODS: In a prospective study, MxA and CRP were measured in the blood by the AFIAS panel in adults admitted with respiratory infection. Patients were split into discovery and validation cohorts. Final diagnosis was adjudicated by a panel of experts. Microbiology-confirmed cases comprised the discovery cohort, and infections adjudicated as highly probable viral or bacterial comprised the validation cohort. RESULTS: A total of 537 patients were analyzed: 136 patients were adjudicated with definitive viral infections and 131 patients with definitive bacterial infections. Using logistic regression analysis, an equation was developed to calculate the probability for bacterial infection using the absolute value of MxA and CRP. Calculated probability ≥ 0.5 and/or MxA to CRP ratio less than 2 applied as the diagnostic rule for bacterial infections. This rule provided 91.6% sensitivity and 90.4% negative predictive value for the diagnosis of bacterial infections. This diagnostic sensitivity was confirmed in the validation cohort. A MxA/CRP ratio less than 0.15 was associated with unfavorable outcome. CONCLUSION: The calculation of the probability for bacterial infection using MxA and CRP may efficiently discriminate between viral and bacterial respiratory infections.

Diagnostic strategies in adrenal insufficiency.

PURPOSE OF REVIEW: Adrenal insufficiency (AI) is the clinical manifestation of deficient production of glucocorticoids with occasionally deficiency also in mineralocorticoids and adrenal androgens and constitutes a fatal disorder if left untreated. The aim of this review is to summarize the new trends in diagnostic methods used for determining the presence of AI. RECENT FINDINGS: Novel aetiologies of AI have emerged; severe acute respiratory syndrome coronavirus 2 infection was linked to increased frequency of primary AI (PAI). A new class of drugs, the immune checkpoint inhibitors (ICIs) widely used for the treatment of several malignancies, has been implicated mostly with secondary AI, but also with PAI. Salivary cortisol is considered a noninvasive and patient-friendly tool and has shown promising results in diagnosing AI, although the normal cut-off values remain an issue of debate depending on the technique used. Liquid chromatography-mass spectrometry (LC-MS/MS) is the most reliable technique although not widely available. SUMMARY: Our research has shown that little progress has been made regarding our knowledge on AI. Coronavirus disease 2019 and ICIs use constitute new evidence on the pathogenesis of AI. The short synacthen test (SST) remains the 'gold-standard' method for confirmation of AI diagnosis, although salivary cortisol is a promising tool.