Although current versions of antimicrobial susceptibility testing (AST) exist, they are typically slow and are only able to accurately detect certain strains of bacteria. Because bacterial infections spread quickly, rapid diagnosis is essential for patient safety.

This new AST would bypass the usual labor-intensive culturing or isolation of the pathogen strain, using instead an optical imaging technique to detect the individual bacterial cells and examine their subtle activity.

“By accurate imaging of sufficient numbers of bacteria cells in raw patient samples, our method can track and extract multiple phenotypic features of each bacterial cell in response to the antibiotics and determine whether the bacteria is susceptible or resistant to certain antibiotics,” Zhang said.

A major contributor of antibiotic resistance is the fact that broad spectrum antibiotics intended to protect against more than one infection are not being used properly. Overuse of such antibiotics, particularly in the agricultural sector, significantly increases the likelihood of bacterial resistance. In the ceaseless arms race between pathogens and our best therapies, the bugs are often winning, as development of effective new drugs becomes more challenging.  

“The antibiotic resistance global health crisis is exacerbated by the worldwide overuse of antibiotics and the decline in the discovery of new and effective antibiotics,” Haydel said.

Technologies such as AST could help mitigate this serious problem, providing “precise antibiotic prescriptions that could reduce the overuse and misuse of broad-spectrum antibiotics,” Zhang said.

This test would not only direct more specific antibiotic prescription, but it could also be utilized in future drug development. Drawing from knowledge of susceptibility, investigators could develop new treatments to target resistant bacterial strains.

Haydel has already considered potential applications for her lab’s studies.

“In my lab, apart from this project, we are working with novel antimicrobial compounds for treating multidrug-resistant and difficult-to-treat bacterial pathogens. I am hoping that we will be able to use this technology for clinical microbiology testing of these novel antimicrobials,” Haydel said.

The investigators believe that this joint effort between their two areas of expertise was made possible by the collaborative effort fostered by Biodesign and other schools within ASU.

“Biodesign and Ira A. Fulton Schools of Engineering provide not only the top research lab and facilities for the work, but also a unique multidisciplinary research environment, which is critical for the project,” Tao said.

Tao and Haydel’s lab will work in collaboration with Thomas Grys of the Clinical Microbiology Laboratory at Mayo Clinic and Win Ly of Biosensing Instrument Inc. Grys will supervise clinical tests with the samples, and Ly will lead efforts for instrumentation design and construction.

Gabrielle Hirneise

Assistant science writer , Biodesign Institute