The Loh Down On Science

A tuning fork even nonmusicians will appreciate

Image courtesy of Longo et al., Nature Nanotechnology, June 2103.

Figure 1. Schematic representation of the setup and the flexible cantilever. a, Top: representation of the cantilever (C) after the attachment of living bacteria (B). Bottom: optical image of a cantilever, on which several adsorbed bacteria can be distinguished. The length of the cantilever is 205 mm. b, Top: representation of C in the acquisition chamber (A.C.), which is flushed by different liquids through the injection system (Inj.). The chamber is equipped with input (In) and output (Out) tubes for changing the media. Bottom: AFM illumination-detection system to measure the fluctuations of C. A laser beam (L) is focused on C. Its reflection is collected by a detector (D), allowing calculation of the sensor deflections. c, Depiction of the fluctuations of C produced by B adsorbed on its surface.

Are antibiotics working or not?  Sick people have had to wait to find out—until now!

This is Sandra Tsing Loh with The Loh Down on Science.

Often, learning if an antibiotic is killing bacteria involves culturing the critters and watching for decreased growth rates.  Boring!  (And slow!)  Now, Swiss researchers have developed a device that can tell in minutes if antibiotic-treated bacteria are dying!

It's a microscopic cantilever, or flexible bar, that vibrates like a tuning fork.  When living bacteria are grown on the bar, the bar vibrates minutely.  It's thought the bacteria's metabolic reactions are causing the motion.  Dead bacteria don't move.  

In a test, the team treated E. coli growing on the bar with antibiotics.  They found the bar’s movements decreased by twenty-fold within minutes!  So the antibiotic was working!

Another test with antibiotic-resistant E. coli showed decreased motion for 15 minutes following antibiotic treatment.  Then increased motion.  Meaning the bacteria suffered a setback, but recovered.  Time to try something else.

With bacteria, you could say, “Stick a fork in it—you’re done!”

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The Loh Down on Science is produced by LDOS Media Lab, with 89.3 KPCC. And made possible by the generous support of the Gordon and Betty Moore Foundation.

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