Blood Marker for Bacterial Infections, Like Pneumonia, May Lead to Diagnostic Test

Blood Marker for Bacterial Infections, Like Pneumonia, May Lead to Diagnostic Test

A team led by researchers at Imperial College London have identified two genes that are activated only in the presence of bacterial infection. This finding may lead to the development of a diagnostic test that can quickly identify potential life-threatening diseases like pneumonia, and help ensure that people with less serious viral infections — especially children — aren’t given antibiotics needlessly.

The research paper, “Diagnostic Test Accuracy of a 2-Transcript Host RNA Signature for Discriminating Bacterial vs Viral Infection in Febrile Children,” was recently published in The Journal of the American Medical Association

Bacterial and viral infections can be difficult to distinguish between based on their clinical features, like a fever. As a result, unnecessary antibiotic treatments are prescribed and bacterial infections are missed and improperly addressed, which can lead to such serious conditions as meningitis, septicaemia, and pneumonia.

“Fever is one of the most common reasons children are brought to medical care. However every year many children are sent away from emergency departments or doctors’ surgeries because the medical team thinks they have a viral infection, when in fact they are suffering from life-threatening bacterial infections — which are often only diagnosed too late,” Professor Michael Levin, who led the study, said in a press release. “Conversely, many other children are admitted to hospital and receive antibiotics because the medical team are unable to immediately exclude the possibility of a bacterial infection — but in fact they are suffering from a virus.”

Researchers studied records of 240 children who had arrived, with fever, at hospitals  across the U.K., Spain, the Netherlands, and the U.S. Viral and bacterial infections were first identified through traditional methods, with 52 children presenting definite bacterial infections, 92 with definite viral infections, and 96 with undetermined infections.

The scientists then examined genes that had been switched on in the children’s immune white blood cells, using a method called RNA microarrays. This method allowed them to measure, from a single drop of blood, changes in 48,000 genes simultaneously. The researchers identified two genes, IFI44L and FAM89A, that are switched on during bacterial infection. Further tests showed that these two genes could predict  bacterial infection with 95% to 100% accuracy.

“Although this research is at an early stage, the results show bacterial infection can be distinguished from other causes of fever, such as a viral infection, using the pattern of genes that are switched on or off in response to the infection,”  Levin said. “The challenge is now to transform our findings into a diagnostic test that can be used in hospital emergency departments or GP surgeries, to identify those children who need antibiotics.”

Researchers are now focusing on validating these findings in studies in larger numbers of children.

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Margarida graduated with a BS in Health Sciences from the University of Lisbon and a MSc in Biotechnology from Instituto Superior Técnico (IST-UL). She worked as a molecular biologist research associate at a Cambridge UK-based biotech company that discovers and develops therapeutic, fully human monoclonal antibodies.

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