FebriDx for C-reactive protein (CRP) and myxovirus resistance protein A testing

CRP is a non-specific indicator for the presence of acute inflammation, which can be raised when there is bacterial infection (1,2)

MxA is a protein marker that is raised in the blood when there is acute viral infection.

Simultaneous measurement of MxA and CRP in people with acute febrile respiratory infections is designed to help differentiate between viral and bacterial infections (2)

• can then guide appropriate use of antibiotics
• tests that improve clinical decision making in antibiotic prescription at the point of care could support antimicrobial stewardship

FebriDx is a self-contained, portable, all-in-one test device, which both collects and analyses the blood sample (2):

• consists of a single strip test card, a buffer solution activated by an integrated push button, lancet and collection tube
• no extra equipment is needed

The FebriDx test card has a single lateral-flow test strip with monoclonal anti-MxA and anti-CRP antibodies

• the lancet punctures the skin and the first drop of blood is discarded
• after this, a 5 microlitre blood sample is collected at a 45-degree angle using the blood collection tube
• the blood is transferred into the blood transfer zone when the collection tube is full, and the buffer solution is applied by fully depressing the buffer release button
• the test is left to develop for 10 minutes on a flat surface before the results are analysed and displayed in the result window.

Point-of-care testing should be considered in primary care for people with suspected lower respiratory tract infections.

Point-of-care CRP tests should be considered for people with symptoms of respiratory tract infection in primary care, if a diagnosis is unclear after clinical assessment (3)

• antibiotic prescribing should be based on the results
• immediate antibiotic treatment should be offered if the CRP level is more than 100 mg per litre and a delayed prescription should be considered at levels between 20 mg and 100 mg per litre

Reference:

• Shirley M. FebriD: A Rapid Diagnostic Test for Differentiating Bacterial and Viral Aetiologies in Acute Respiratory Infections. Mol Diagn Ther. 2019; 23(6): 803–809
• NICE (August 2020). FebriDx for C-reactive protein and myxovirus resistance protein A testing
• NICE (September 2016). QuikRead go for C-reactive protein testing in primary care