'Simple blood test to tell if patients need antibiotics'

In a breakthrough, researchers, including one of Indian-origin, are developing a simple and low-cost blood test that can accurately identify which patients need antibiotics.
Antibiotics have saved millions of lives and created a world in which complex and lifesaving surgeries are possible.
But the overuse of antibiotics threatens to create a global scourge of antibiotic-resistant bacterial pathogens, researchers said.
"A lot of times you cannot really tell what kind of infection someone has. If someone comes into the clinic, a bacterial or a viral infection often look exactly the same," said Timothy Sweeney from Stanford University in the US.
"The idea to look for a diagnostic test came from our previous paper in Immunity last year. In that paper, we found a common response by the human immune system to multiple viruses that is distinct from that for bacterial infections," said Purvesh Khatri from Stanford.

"We wondered whether we could exploit that difference to improve the diagnosis of bacterial or viral infections. But we needed a gene signature consisting of far fewer genes for the test to be clinically useful," said Khatri.

Researchers used publicly available patient gene expression data to pinpoint just seven human genes whose activity changes during an infection. Their pattern of activity can distinguish whether an infection is bacterial or viral.
When pathogens infect the cells of the body, the infection sets off a chain reaction involving the immune system that changes the activity, or expression, of hundreds of genes, researchers said.

Gene expression is the process by which cells extract information from genes and render it in the form of either protein or RNA molecules, they said.
Cells have the capacity to express more or less of each molecule, creating a pattern of gene expression that changes in response to external influences, including infections.
The seven-gene test is a vast improvement over earlier tests that look at the activity of hundreds of genes, researchers said.
Because so few genes are involved, the new test will be cheaper and faster, while remaining accurate, they said.
Researchers are working to engineer the gene expression test to provide results in under an hour.

The findings were published in the journal Science Translational Medicine.