A matchbox-sized device that eavesdrops on the metabolic hum of bacteria could provide a vital aid to doctors treating infections.
The microbe "bug" can speed up tests for the presence of infection from weeks to a couple of minutes.
The device employs a tiny lever, slightly thicker than a human hair, that is made to vibrate by bacterial activity. A sensitive laser picks up the vibration and translates it to an electrical signal, shown on a display similar to a heart monitor. When the signal "flatlines" it shows the bacteria are dead.
"This method is fast and accurate," said lead researcher Dr Giovanni Dietler, from the Swiss technology institute EPFL in Lausanne. "It can be a precious tool for both doctors looking for the right dosage of antibiotics and for researchers to determine which treatments are the most effective."
Currently it can take weeks to measure bacteria's response to antibiotic treatment, said the researchers. Clinicians must culture the bacteria and then observe its growth, sometimes for almost a month as in the case of tuberculosis.
To overcome the problem, the Swiss scientists developed a way of "listening" to the almost imperceptible vital signs of bacteria. Vibrations from living bugs cause oscillations in the lever of the order of one millionth of a millimetre.
The team, whose research is reported in the journal Nature Nanotechnology, hopes to shrink the device further to the size of a microchip by swapping the laser for a piezoelectric sensor.
A number of devices could then be combined together to test the effectiveness of a several antibiotics at once. Another potential application of the technology is monitoring the response of tumour cells to cancer drugs.
Co-author Dr Sandor Kasas, also from EPFL, said: "If our method also works in this field, we really have a precious tool on our hands that can allow us to develop new treatments and also test both quickly and simply how the patient is reacting to the cancer treatment."