Early results are promising and this technology could lead to a clinical laboratory test that would give microbiologists and pathologists a new tool for helping diagnose infections

Infectious disease physicians and clinical laboratory scientists will be interested to learn that researchers at the Stanford University School of Medicine recently developed a new blood test that can identify whether the source of an infection is bacterial or viral.

These findings were published in Science Translational Medicine in July. The paper was authored by Stanford staff members Timothy Sweeney, MD, PhD, and Purvesh Khatri, PhD, Assistant Professor (Research) of Medicine (Biomedical Informatics Research-ITI Institute) and of Biomedical Data Science. Hector Wong, MD, of the University of Cincinnati was the third co-author of the study.

These findings are timely because, starting on January 1, 2017, hospitals and health systems will need to implement more rigorous antimicrobial stewardship programs to comply with new requirements of the Centers for Medicare & Medicaid Services (CMS) and The Joint Commission (TJC). A clinical laboratory test that makes it easier to determine whether the cause of an infection is bacterial or viral would be a welcome tool for physicians, pharmacists, pathologists, and microbiologists involved in a hospital’s infection control program.

Clinical Labs Have No Method to ID Viral versus Bacterial Infections

Healthcare professionals have long been advised to prescribe antibiotics for bacterial infections, such as strep throat caused by streptococcal bacteria and skin infections caused by staphylococcal bacteria. Since antibiotics kill bacteria, they are ineffective against viruses, such as colds, most coughs, and influenza. Currently, there are no reliable methods available to determine whether an infection is viral or bacterial, which can restrict the ability of physicians to properly treat an infection.

“A lot of times you can’t really tell what kind of infection someone has,” observed Sweeney, who is Engineering Research Associate with the Stanford Institute for Immunity, Transplantation and Infection, and lead author of the paper, in a Stanford news release. “If someone comes into the clinic, a bacterial or a viral infection often look exactly the same.”

New Test is Faster, Cheaper, More Accurate

The new, simple blood test examines the activity patterns of seven human genes during an infection, and the biomarkers look at an immune system response. Previous, similar tests analyzed hundreds of genes. Since only seven genes are probed in this cutting-edge test, researchers say it will be faster and more economical while providing accuracy.

Antibiotics and similar drugs—collectively known as antimicrobial agents—have saved millions of lives since their introduction during the last century. But the drugs have been so popular for so long that the infectious organisms they were designed to kill have adapted to them. This condition, known as antimicrobial or antibiotic resistance, renders the drugs less effective.

Antibiotic Resistance Leads to Increased Deaths

The ineffectiveness of antibiotics can result in longer and more complicated illnesses, more doctor and hospital visits, the use of stronger and more costly drugs, and more deaths associated with bacterial infections.

According to the Centers for Disease Control and Prevention (CDC), at least two million people become infected with bacteria that are resistant to antibiotics each year in the United States. Approximately 23,000 of these people will die as a result of these infections. There are about 154 million antibiotic prescriptions written in the US each year and it is estimated that around one third of these prescriptions are unnecessary.

The Stanford researchers plan to combine the new seven-gene test with an already existing 11-gene test that indicates whether an infection is present or not. The new 18-gene test will determine if the patient has an infection and whether it is viral or bacterial in nature.

A Stanford University research team led by Purvesh Khatri, PhD, and Timothy Sweeney, MD, PhD, has developed a new 18-gene test by combining two other gene tests. The new test is accurate, inexpensive, and can determine whether infections are viral or bacterial, which will help doctors when prescribing treatment. (Photo copyright: Stanford University.)

A Stanford University research team led by Purvesh Khatri, PhD, and Timothy Sweeney, MD, PhD, has developed a new 18-gene test by combining two other gene tests. The new test is accurate, inexpensive, and can determine whether infections are viral or bacterial, which will help doctors when prescribing treatment. (Photo copyright: Stanford University.)

“When you put the new seven-gene set together with the 11-gene set, we can make a decision tree that matches how a physician might think about a patient,” stated Sweeney in the news release. “First we ask, ‘Is an infection present?’ Because some people present with an inflammation, a fever, a high heart rate, but it’s not due to an infection. Then we ask, ‘If so, what kind?”

Researchers Seek Low Cost Test to Spark Adoption

Before the new test can be made available, it must be thoroughly tested in a clinical setting. In developing the test, the researchers examined pre-existing digital data sets of blood samples from 96 critically ill children who were not current patients. Evaluating that data with their new test resulted in a 98.5% accuracy rate of diagnosis.

Researchers also indicated this new diagnostic test must be integrated into a device that can give speedier results, whether for use in medical laboratories or in point-of-care settings. It currently takes four to six hours to produce results from the seven-gene test. This is considered too long for patients who are seriously ill.

The cost of the 18-gene test has yet to be determined. Researchers hope to keep the price point equal to or less than the cost of the inexpensive antibiotics that are currently on the market. The hope is that the low cost will motivate physicians to utilize the blood test before writing prescriptions that might be unnecessary or ineffective.

As that happens, this technology would then provide clinical laboratories with a useful diagnostic test that can more accurately identify the cause of an infection. In turn, such a test might become part of a hospital’s antimicrobial stewardship program.

Antimicrobial stewardship programs—a new requirement of Medicare CoP (Conditions of Participation) and Joint Commission accreditation of hospitals as of January 1, 2017—will be discussed at a special webinar hosted by Dark Daily on November 16, 2016, at 1 PM Eastern. The webinar is designed to give hospital-based lab professionals a head start on ways they can contribute more value to their institution’s antimicrobial stewardship program. Visit Dark Daily’s webinar page for details and to register for this exceptional webinar.

—JP Schlingman

Related Information:

Cheap Blood Test Can Discriminate Between Bacterial, Viral Infections

Simple Blood Test Distinguishes Between Viral, Bacterial Infections

Robust Classification of Bacterial and Viral Infections via Integrated Host Gene Expression Diagnostics (Abstract)

Combating Antibiotic Resistance

Webinar: ‘Big Bang’ of Antimicrobial Stewardship Programs Comes to All Hospitals on January 1: What Labs, Pharmacies, and Clinicians Must Do Collaboratively to Meet New Medicare and TJC Requirements