Fast electronic test determines if bacteria are antibiotic-resistant

Ordinarily, in order to determine if an infectious bacteria is resistant to certain antibiotics, cultures of that bacteria have to be grown and tested in a lab. The process can take two days or longer, during which time the patient may be getting treated with antibiotics that are later found to be ineffective.

Seeking a speedier alternative, scientists at Washington State University have developed a technique in which an electronic probe is used to measure the electrochemical signal produced by bacteria as they metabolize and breathe. If a bacterial sample is exposed to a given antibiotic, and that signal continues to be emitted, it means that the medication failed to kill the microbes. Doctors can then test other antibiotics, or pursue other treatments – and they can do so within less than an hour and a half of beginning the first test.

Although researchers have previously tried to perform such measurements, they were foiled by the fact that most bacteria are incapable of transferring electrons directly to an electrode. The Washington State team addressed this problem by utilizing a chemical "mediator" that shuttles electrons from the surface of the bacteria to the electronic probe, where they can be detected.

The technology has already been successfully tested on four common types of infection-causing bacteria, which were exposed to four different antibiotics. Plans now call for the system to be developed further and commercialized, with hopes that it may ultimately be able to deliver results within a matter of minutes.