IEEE Spectrum April, 2014 - 22

nEwS

SuPerBuG SuPerSleuth: F Cubed's chip uses
an electric field to tease out the presence of a MRSA
bacterium's DNA.

DNA's double helix structure into two single
strands. Then a pump sends that DNA through
the chip's nanofluidic channel, where minus‑
cule probes hold single strands of DNA unique
to the MRSA bacterium. Electrode microarrays
on the sides of the chip create an electric field
throughout the channel. If MRSA is present
in the patient's body, the DNA in the sample
will bind to the complementary DNA on the
probes, changing the conductivity of the sys‑
tem. If the biochip detects that change, that
means the MRSA bug is present in the sample.
Ivie says this system is cheap to manufac‑
ture because, unlike many other genetics‑
based tests, it doesn't use any fluorescence
or optics. "All we are doing is measuring
electrical changes, which is very simple to
A lab-on-a-chip could quickly tell if an infection is
do,"
he says. Another advantage, Ivie says,
the dreaded antibiotic-resistant mrSA
is ease of use. Other lab tests require techni‑
cians to isolate the DNA of just one species in
the sample and are vulnerable to contami‑
Les Ivie, president and CEO of F Cubed, nation, but the F Cubed system works even
It's an irony of our time that checking into a hospital can kill you, thanks which is in South Bend, Ind., says that de‑ if the DNA of multiple microbe species is in
the mix; the biochip will register the MRSA
to several antibiotic‑resistant superbugs that
spite the pressing need, doctors lack a quick
bacterium's DNA if it's present, and the rest
have found niches in health‑care facilities. and easy test to diagnose MRSA. The fastest
Now, to combat the menace of one particu‑ lab tests today take many hours, and they're will just wash through the channel and out
larly lethal strain of bacteria, doctors at four so expensive that physicians rarely opt for of the chip. "Our process could be done by
a physician in an emergency room, in the
them. "If you were to check into a hospital
hospitals in the United States are trying out
back of a truck, or in the middle of the des‑
a speedy method to identify patients who with a suspected infection, typically they
have MRSA (methicillin‑resistant Staphylo- would do a plate culture to grow bacteria, ert," Ivie says. "It does not have to be clean."
and that takes three to four days," he says.
This technology could be a great boon in
coccus aureus).
Using a lab‑on‑a‑chip technology from a "The problem is that if you have a MRSA emergency rooms, says Richard Wenzel, a
infection, you may not have three to four physician at the Virginia Commonwealth Uni‑
start‑up called F Cubed, physicians should
be able to diagnose MRSA within an hour, days before it gets into your bloodstream." versity and an expert on MRSA prevention
The heart of the F Cubed system is a dis‑ and treatment in hospitals. "If the patient
and without leaving the emergency room.
F Cubed hopes that this year's clinical trial
posable biochip measuring 7 by 14 milli‑ has actual pus somewhere and you could
will lead to a commercial device.
know within an hour whether this really is
meters, which snaps into a molded plastic
MRSA infections start on the skin or in
MRSA and should be treated appropriately,
panel that handles the sample flow and
a wound, but they can spread through the waste. The biochip is based on research by that would be very useful," he says. However,
bloodstream to cause life‑threatening ill‑ Hsueh‑Chia Chang, director of the Center Wenzel says, because of increased vigilance
by hospital staff, few MRSA patients go un‑
nesses like pneumonia and sepsis. The U.S. for Microfluidics and Medical Diagnostics
Centers for Disease Control recently esti‑ at the University of Notre Dame, in Indiana. treated today. "What we're doing now is just
treating all skin and soft tissue infections like
mated that more than 80 000 people got The plastic panel is inside a suitcaselike
container along with the components that MRSA, because in 70 to 75 percent of the
invasive MRSA infections in 2011, and more
cases that's what they turn out to be," he
than 11 000 of those patients died. Most manage the rest of the testing process, from
says. "That would be the caveat to saying
of those serious infections, says the CDC, sample preparation to the final readout.
The device first isolates the DNA in a pus
this diagnostic tool is a major breakthrough."
occurred during or soon after inpatient
sample from a wound and breaks apart the -eliza str ick l a nd
medical care.
22

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peter riNgeNberg

biocHip vs. superbug

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Table of Contents for the Digital Edition of IEEE Spectrum April, 2014