A test that looks for specific patterns of genes that are switched on may lead to a better way of diagnosing dangerous yeast infections in the blood, U.S. researchers said on Wednesday.

They said mice infected with the Candida albicans fungus have a telltale signature of genes that are active, or expressed, that is not found in the blood of healthy mice.

"This study provides the basis for development of a blood-gene expression tests in humans to detect a life-threatening infection earlier than can be done using currently available methods," said Dr. Geoffrey Ginsburg of Duke University in North Carolina, whose study appears in the journal Science Translational Medicine.

Candida is the fourth most common bloodstream infection in the United States, yet it is often hard to distinguish from a bacterial infection. Antibiotics are useless against yeast infections, which can be treated with antifungal drugs instead.

The yeast-like fungus normally lives in the mouth and gastrointestinal tract without causing trouble, but antibiotics or other drugs can kill off competing bacteria and cause an overgrowth.

When Candida organisms enter the blood, they can be disseminated throughout the body, causing severe illness. Candida infections can kill 10-15 percent of critically ill patients within the first 24 hours of infection. If undetected for up to three days, they kill 30 percent of patients.

For the study, the team took blood samples and compared the patterns of genes that were expressed in mice infected with or without a yeast infection and in those infected with a bacterial infection.

Using this, they created a genetic pattern or signature associated with yeast infection.

"We were very pleased to learn that we could further distinguish the fungal infection from a staph infection, another bloodstream disease that shares the same set of symptoms," Dr. Aimee Zaas of Duke who worked on the research said in a statement.

The team hopes the findings will form the basis of a gene-based blood test for hospitalized patients.