NIST's Sensor Technique Provides Faster Testing for Antibiotic Susceptibility

With researchers around the world on the hunt for new ways to fight antibiotic-resistant bacteria, scientists from the National Institute of Standards and Technology (NIST) have developed a device that can detect if an antibiotic is effective against a specific pathogen.

Last year a study conducted by researchers from the Centers for Disease Control and Prevention (CDC) along with Pew Charitable Trusts noted that at least 30% of antibiotics prescribed in the United States are unnecessary. Although many of those antibiotics were administered in error for illnesses caused by viruses, CDC health officials also emphasized that to fight antibiotic resistance, it’s important that doctors prescribe the right antibiotic in the right dose when an antibiotic is needed.

To this end, researchers have been developing tools to differentiate between viral and bacterial infections and earlier this year the World Health Organization (WHO) called for new rapid diagnostic tools to quickly identify the cause of infections. Now, in a recent study published in the journal Scientific Reports, researchers from NIST describe a new prototype sensor capable of quickly detecting the antibiotic susceptibility of bacterial pathogens in rapid time.

The new prototype sensor works by using a quartz crystal resonator coated with bacterial cells to detect changes in vibrations when particles on the surface change. The highly sensitive crystals allow researchers to measure changes in cell-generated frequency noise—which correlates with the density of living bacterial cells—created by the bacteria activity in response to exposure to antibiotics.

For example, when testing the device on Escherichia coli bacteria exposed to the antibiotics ampicillin and polymyxin B, the researchers observed a sharp drop in frequency noise within 7 and 15 minutes, respectively, of exposure to the antibiotics, reflecting the speed at which antibiotics begin to work.

Contagion^® spoke about the study with senior author and NIST physicist Ward L. Johnson, PhD, who explained that the research was aimed at solving physicians’ needs to quickly choose the right antibiotic when writing prescriptions for patients, properly treat patients, and practice antibiotic stewardship. “However, it is often impossible for physicians to achieve the goal of responsible antibiotic use while protecting the health of a patient, because of a lack of timely information on the efficacy of antibiotics in treating a specific infection,” said Dr. Ward. “This untenable situation is driving efforts to develop rapid methods for antimicrobial susceptibility testing, such as our work.”

Although much additional research is needed on the new sensor before it can be developed for use in a clinical setting, Dr. Johnson sees a potential for the use of his tool alongside others, such as a rapid diagnostic device, to help doctors quickly diagnose and treat patients. “Advanced DNA/RNA-based technologies can identify microbes quickly but cannot directly determine antibiotic efficacy and, therefore, are limited in their ability to determine effective antibiotics for bacterial strains with new resistance mechanisms,” explained Dr. Johnson. “We envision that these technologies could be employed in tandem with our sensing approach to identify newly resistant strains.”

The timing could not be more appropriate, as, in the United States alone, an estimated 2 million people become infected with antibiotic-resistant bacteria each year, resulting in at least 23,000 deaths. If physicians are eventually able to rapidly detect the pathogen at the point-of-care, and determine the most appropriate treatment, patients will be administered the most effective antibiotic for their infection, thus aiding in decreasing growing resistance.