Test determines antibiotic resistance in less than 90 minutes

Date:
November 3, 2021
Source:
Washington State University
Summary:
A technique that measures the metabolic activity of bacteria with
an electric probe can identify antibiotic resistance in less than
90 minutes, a dramatic improvement from the one to two days required
by current techniques.



FULL STORY ==========================================================================
A technique that measures the metabolic activity of bacteria with
an electric probe can identify antibiotic resistance in less than 90
minutes, a dramatic improvement from the one to two days required by
current techniques.


==========================================================================
This discovery means that doctors could quickly know which antibiotics
will or won't work for a patient's life-threatening infection, a quandary
that doctors face on a daily basis in hospitals around the world. A
Washington State University research team reports on their work in the
journal, Biosensors and Bioelectronics.

"The idea here is to give the doctors results much more quickly so that
they can make clinically appropriate decisions within that timeframe
that they're working, rather than having to wait," said Douglas Call,
Regents Professor in the Paul G. Allen School for Global Health and a
co-author of the paper.

"Instead of looking for growth of a culture, we look for metabolism,
and that is basically what we're detecting by the movement of these
electrons so it can happen in much shorter time spans compared to
a conventional culture-based assay." The prevalence of antibiotic
resistance is increasing around the world and threatens the ability to
treat many common infectious diseases. For example, millions of people
in the U.S. are infected annually with drug-resistant pathogens, and
thousands of people die from pneumonia or bloodstream infections that
become impossible to treat.

To determine definitively whether a particular infection is resistant
to antibiotics requires separating and then growing the bacteria in a
lab and watching the population grow in a process that can take up to
two days or more.

Doctors who are faced with a sick patient often have to prescribe an
antibiotic immediately without having complete information on how well
it will work.

In their paper, the WSU team used a probe to directly measure the electrochemical signal of the bacteria, thereby measuring their metabolism
and respiration and learning how they are faring long before they would
be visible in culture. Looking at eight different strains of bacteria,
the researchers were able to use the bacteria's electric signal to
determine in less than 90 minutes which were susceptible or resistant
to the antibiotics.



==========================================================================
The bacteria that are still metabolizing and "breathing" after antibiotic treatment are considered resistant.

Previous attempts to measure the electrochemical activity of bacteria
had been limited because most bacterial species are not capable of
transferring electrons directly to an electrode, said Abdelrhman Mohamed,
a postdoctoral researcher in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering who was a lead author on the paper. The researchers added a chemical mediator to their assay, which acted as a
shuttle, taking the electrons from the surface proteins of the bacteria
and moving them to the researchers' electrode, where the electric signal
can be measured.

"That allows us to have a universal mechanism that can test all types
of pathogens," said Mohamed.

The researchers tested four different bacterial species that cause
hospital- acquired infections and tested a variety of antibiotics that
work by way of different mechanisms. They also developed an antibiotic susceptibility index to categorize the results in a way that could help
doctors decide which antibiotic to use.

The researchers are now planning to engineer their probe to be convenient
and standardized for clinicians to use and hope to commercialize it.

"It's really exciting to be involved in a project that not only is
valuable from a scientific view but is something that has commercial and industrial applications that could potentially someday actually improve people's lives," said Gretchen Tibbits, a lead author on the paper and
graduate student in the Voiland School.

They are also working to better understand the fundamental mechanisms
of the electrochemical process to further improve it.

"We are doing it in two hours, but if we understand mechanisms
better, maybe we can do this in minutes," said Haluk Beyenal,
co-author on the paper and a professor in the Voiland School. "As
long as the bacteria are alive, we can do this measurement." ========================================================================== Story Source: Materials provided by Washington_State_University. Original written by Tina Hilding. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Gretchen Tibbits, Abdelrhman Mohamed, Douglas R. Call, Haluk
Beyenal.

Rapid differentiation of antibiotic-susceptible and
-resistant bacteria through mediated extracellular electron
transfer. Biosensors and Bioelectronics, 2021; 113754 DOI:
10.1016/j.bios.2021.113754 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211103082618.htm

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