Breakthrough made in identifying bacteria and treating infections

Waterloo, ON – Research by University of Waterloo chemistry professor Dr Susan Mikkelsen and former PhD student Peter Ertl has the potential to radically improve the response time of identifying and treating infectious disease.

Based on a new advanced electrochemical technique, unknown bacteria and the antibiotics to which the bacteria are most susceptible can be identified. This method can provide test results in less than 30 minutes from a clinical isolate, which is much less than current technology that generates results somewhere between four hours and 72 hours.

As a result, patients can be placed on more appropriate and effective antibiotics much more quickly. In addition, hospitals can manage contagious disease and secondary infections with greater knowledge and improved efficiency.

Most established, commercially available methods rely on the observation of growth over a longer period of time (four hours to several days). These existing methods compare the extent of growth for microorganisms cultivated in the absence and the presence of antibiotic. The new technology is based on a direct measurement of cellular activity and eliminates the need for long periods of bacterial growth.

“Speeding up the process to identify and determine the most effective antibiotics to be used will have a significant positive impact on the patient and on the healthcare system,” said Jeff Hendrikse of RapidLabs (Rapid Laboratory Microsystems), the company that will commercialize the intellectual property originating at UW.

Six years ago, Mikkelsen and Ertl were performing different experiments in their labs. Although the experiments involved microorganisms (bacteria and yeasts) and electrochemical measurement techniques, both researchers were unprepared for what they discovered. (Ertl is now a research associate at the Institute of Nano-System Technologies, a division of the Austrian Research Centres, in Vienna.)

They learned it’s possible to measure the viability (life and death) of a bacterial culture by making electrochemical recordings of respiration, just as a doctor measures a patient’s lung capacity. Further, by killing the bacteria with antibiotics, they found that respiration measurements were much faster than standard methods for determining drug effectiveness.

The presence of an effective antibiotic causes a decrease in the respiration of the bacteria, while the presence of an antibiotic to which the bacteria is resistant does not cause any change in the bacteria’s respiration. The results of this antibiotic susceptibility test indicate which antibiotics a physician should use to fight the patient’s infection or disease.

Later, it was shown that the new measurement technique could also be used to identify bacteria. Respiration measurements made after exposure of the bacteria to various chemicals (such as sugars and amino acids) yield a unique pattern of responses for each bacterial species. With a database of known bacterial respiration measurements, unknown bacteria can easily be identified, Mikkelsen said.