Work by the Canadian University of Waterloo chemistry Professor Susan Mikkelsen and PhD student Peter Ertl has revealed a new method of identifying bacteria and antibiotic susceptibility from a clinical sample in less than 30 minutes. The research is based on a newly advanced electrochemical technique, that looks at… bacterial respiration:
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.
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.
Antibiotic susceptibility and microbial identification tests are routine procedures used in outpatient and hospital laboratories to determine which antibiotic is most effective against a disease-causing organism. The use of these tests has been steadily increasing due to the introduction of new drugs as well as the emergence of antibiotic resistant organisms. The test results provide attending physicians with valuable information when prescribing drugs to patients.