|A new piezoelectric sensor can identify the most appropriate antibiotic
for an infection in less than an hour, according to physicists in the
US. While conventional antimicrobial tests can take days, the device
detects changes in bacteria motion upon initial exposure to antibiotics.
Faster antibiotic selection could improve treatment outcomes and help
tackle antimicrobial resistance.
Antimicrobial susceptibility testing (AST) is used to identify the most
appropriate antibiotic for a bacterial infection. Current tests are
constrained by bacterial growth rates, as they examine the effect of
antibiotics on the growth of bacteria colonies cultivated from patient
samples. However, the two to three days this takes to produce results
can cause problems.
To accelerate AST, researchers from the National Institute of Standards
and Technology (NIST) in Boulder, Colorado are developing a biophysical
method that can measure changes in mechanical fluctuations of bacteria.
Their sensor is based on thin quartz crystal disc, with an electrode on
each surface. One of the electrodes is used to deliver an electrical
signal that is close to the disc's resonance frequency, while the other
measures the piezoelectric voltage created by the resulting crystal
vibrations. The technique involves coating the disk in bacteria.
Fluctuations in the mechanical properties of the organisms affect the
frequency of the output signal, which in turn can be used to detect
changes in the bacteria population when exposed to the antibiotics.