In the U.S., each year at least 2 million people acquire serious infections with bacteria resistant to one or more of the antibiotics, resulting in >$20 billion in direct healthcare costs and $35 billion in lost productivity. In particular, nosocomial bloodstream infections (BSI’s), including catheter-related BSI’s, are important causes of patient morbidity and mortality. The annual incidence of BSIs is >750,000 cases, with a 30% mortality rate, and the proportion of antibiotic-resistant bacteria causing BSIs is increasing. Treatment of multidrug-resistant bacteria requires use of broad-spectrum antibiotics, which are often expensive compared to narrow-spectrum antibiotics, and their use promotes bacterial resistance and also infection with Clostridium difficile.  Therefore, rapid initiation of appropriate empiric antibiotic therapy is strongly associated with decreased mortality rates and is highly desired. As a result, the goal of physicians and of all antimicrobial stewardship programs (ASPs) today is to place patients with BSIs and other infection types on targeted narrow-spectrum antibiotic therapy based on antimicrobial susceptibility test (AST) results as quickly as possible.

Current AST methods usually require between 2 to 4 days to be completed by the clinical laboratory, but can require > 3 to 5 days for mixed cultures and other scenarios. This is due to the need for growing the bacterial isolate for at least 16-18 hrs. in culture media, followed by many hours of incubation with antibiotics for the susceptibility test. To shorten the time of performing AST, Drexel’s biomedical engineers and clinicians have developed the Piezoelectric Plate Sensor (PEPS) for generating definitive AST results in less than 30 minutes from blood cultures initially, and, following PEPS optimization, in less than 1hr from drawing the patient sample to AST results. 

To perform the test, PEPS is coated with bacteria and then immersed in different concentrations of antibiotics. Bacteria react to effective antibiotics by changing the PEPS resonance profile, which allows to separate ineffective antibiotics from the effective ones, and to determine their minimum inhibitory concentrations. Currently, PEPS can be performed using commercially available PZT ceramics, which enables running PEPS tests from blood cultures. The proprietary PEPS sensor, which is still being optimized, will eventually enable running AST directly from patient samples and generating results in less than one hour.