Rapid assay distinguishes viral from bacterial infection

LJUBLJANA, SLOVENIA – Bacterial infections quickly can be distinguished from viral infections in febrile children using a novel real-time polymerase chain reaction (PCR) assay assessing RNA expression of a single patient gene, according to a proof-of-concept study presented by Ruth Barral-Arca at the annual meeting of the European Society for Paediatric Infectious Diseases.

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Ruth Barral-Arca

The gene of interest – IFI44L – is entwined in a child’s response to infection. It’s upregulated in the presence of viral infection and suppressed in bacterial infection, explained Ms. Barral-Arca, a PhD student at the University of Santiago de Compostela (Spain).

This investigational real-time PCR assay could provide a major advance over current routine practice, which is to admit a sick febrile child to the hospital, order bacterial cultures, and start parenteral antibiotics presumptively while awaiting the culture results, which usually don’t come back for more than 24 hours. This practice is a step backwards in terms of antibiotic stewardship, because the majority of febrile children have a self-resolving viral infection.

“This is a big problem because a lot of children with viral infections are inappropriately given antibiotics, leading to antimicrobial resistance,” she noted.

Also, misleadingly false-negative bacterial cultures can occur if the causative pathogen wasn’t included in the test, the infection is in a nonaccessible site, or the child has recently been on antibiotics.

All of these shortcomings have led to a new diagnostic strategy based upon measuring the pattern of key host genes upregulated or suppressed during the inflammatory response.

“We’ve seen that, instead of analyzing the bugs, analyzing the host transcriptome response during infection is proving to be a promising tool for disease biomarker identification. And it’s faster. An early differentiation between viral and bacterial patients will help improve triage in emergency departments, decrease the misuse of antibiotics, and guide clinics to a more precise diagnosis. A lot of big hospitals are already doing PCR. They could quickly adopt this kind of analysis,” Ms. Barral-Arca continued.

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She presented a pilot study in which the assay was put to the test using multiple blood samples from 14 febrile infants and children up to 6 years of age with microbiologically confirmed bacterial infection, 11 febrile children with confirmed viral infection, and 10 healthy controls.