FEATURE
for 14 states plus Puerto Rico and surge
capacity nationwide. In 2017-2018, the
laboratory examined over 9,600 specimens
for carbapenem resistance and detected
or confirmed over 300 highly resistant
Acinetobacter isolates, over 1,100 resistant
Pseudomonas isolates and almost 3,500
carbapenem-resistant Enterobacteriaceae
isolates.
Among other successes, Burks said his
scientific team employed a new PCR
method to identify three new AR gene
groups in Acinetobacter. “The number
of Acinetobacter specimens [we receive]
seems to be holding steady,” he said, “but
resistance is surprisingly high—about
70% positive for one of the three genes
Tennessee identified.” But because
there is no reliable pre-AR Lab Network
assessment of carbapenem resistance in
Acinetobacter, Burks said, “We don’t know
if the rate is increasing or if it was already
that high.”
Under the direction of Henrietta Hardin,
MPA, MT(ASCP), the facility’s general
bacteriology manager, the Tennessee
laboratory is also one of four regional
AR Lab Network laboratories testing
for resistance in Neisseria gonorrhoeae
(the so-called GC AR Lab Network). The
bacteriology team tests specimens from
high-prevalence sites across the country
that participate in CDC’s Gonococcal
Isolates Surveillance Program (GISP),
enhanced GISP or Strengthening US
Response to Resistant Gonorrhea program.
Since the laboratory joined the GC AR Lab
Network in spring 2017, it has analyzed
over 5,500 isolates for susceptibility to
seven antibiotics using agar dilution
plates produced in-house. Overall, 7% of
isolates have exhibited drug resistance.
Hardin said her team is now involved in
setting susceptibility “breakpoints” for
new drugs, like gentamicin, which will
hopefully prove effective against some
drug-resistant gonorrhea strains.
Within the state of Tennessee itself,
Kainer said the biggest AR threat is
“an oldie” that is making a comeback:
methicillin-resistant Staphylococcus
aureus (MRSA). She said, “We have seen
very significant increases particularly
among the younger population and more
among females.”
Between 2014 and 2018, the number of
MRSA bloodstream infections reported by
Tennessee hospitals jumped from 2,123 to
3,277—a 54% increase.
“The epidemiology of [MRSA
transmission] is changing,” said Kainer.
“It’s now likely to be driven by the opioid
epidemic—users injecting with tainted
needles, syringes or other paraphernalia.
They often get these MRSA infections
along with endocarditis. Those are very
serious, very expensive, high-mortality
conditions.” In fact, one-year mortality
for hospital-onset MRSA bloodstream
infection in Tennessee runs about 50%.
On the flip side, Kainer said, CPOs carrying
the KPC gene have become notably rarer
in Tennessee. She said, “We attribute
that to improved infection control and
environmental cleaning in healthcare
settings.” And those improvements she
attributes directly to CDC’s stepped-up
investment in AR control.
Before the CARB plan and associated
state funding, Kainer said, “We didn’t
have laboratory capacity for rapid [AR]
detection and identification, and we didn’t
have the public health infrastructure on
the epi and infection control side.”
Today, a single case of CPO infection in
a Tennessee hospital triggers laboratory
testing to identify the infectious organism
and AR gene, sometimes supplemented
by more detailed characterization, such
as whole genome sequencing. In addition,
Kainer’s staff assesses the facility’s
infection control practices—hand hygiene,
environmental cleaning, use of personal
protective equipment and the like—and
collects rectal swabs from potentially
exposed patients as part of a point
prevalence survey to determine whether
transmission has occurred. If laboratory
testing shows CPO colonization in other
patients, further recommendations
are made.
“We continue these point prevalence
surveys every two weeks until we get
two consecutive rounds of negative
transmission,” said Kainer. “Having the
laboratory capacity to process these
colonization swabs is a huge thing. The
whole aim here is timely data to allow us
to take the appropriate infection control
and public health actions. It’s literally a
game-changer.”
Brittany O’Brien and Rokebul Anower review results from the real-time PCR developed for Candida auris. Photo: Wadsworth Center
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LAB MATTERS Summer 2019
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