APHL 2019 POSTER ABSTRACTS
We describe a real-time PCR assay that is accurate, sensitive,
specific, and reproducible. We will implement this assay in parallel
with culture-based colonization testing for 4 months, and will use
the parallel testing data to inform the best testing algorithm for C.
auris colonization screening.
1
Leach L, Zhu Y, Chaturvedi, S. Development and Validation of a Real-Time PCR Assay
for Rapid Detection of Candida auris from Surveillance Samples. J Clin Microbiol.
2018;56(2).
Presenter: Allen Bateman, Wisconsin State Laboratory of Hygiene,
Madison, WI, [email protected]
Carbapenem-Resistant Acinetobacter baumannii Harboring
a Plasmid Carrying blaOXA-72 in an Outbreak Involving
an Intensive Care Unit and Long-Term Care Facilities in
Wisconsin
K. Florek 1 , S. Wagner 1 , M. Lasure 2 , N. Shrivastwa 2 , A. Bateman 1 , D.
Warshauer 1 ; 1 Wisconsin State Laboratory of Hygiene, 2 Wisconsin
Division of Public Health
Background: Acinetobacter baumannii is an opportunistic pathogen
implicated in a variety of healthcare-associated infections and is a
concern in intensive care units. Here we report an outbreak during
October 2018 involving patients in an intensive care unit (Facility
A) in Wisconsin. Initially, Acinetobacter baumannii isolates with
matching antimicrobial susceptibility (AST) profiles were identified
in 5 patients in Facility A, suggesting the potential spread of a
carbapenem resistant Acintobacter baumannii (CRAB).
Methods: AST information was collected from three major clinical
laboratories in the Wisconsin Clinical Laboratory Network on
recent CRAB isolate submissions. An additional 3 isolates from
Facility A and 1 isolate from Facility B were found to match the AST
profile of the original 5 from Facility A. Isolates were submitted
to the Wisconsin State Laboratory of Hygiene where sequencing
was performed using both the Illumina MiSeq and the Oxford
Nanopore MinIon sequencing platforms. To identify if the resistance
mechanism was plasmid-borne, genome assemblies were created
using a short read and long read hybrid assembly method.
Results: Comparison of the 9 isolates by core genome and single
nucleotide polymorphisms (SNPs) indicated that 6 of the 9 isolates
were closely related, one of which was from Facility B. All six isolates
contained a 10,879 bp plasmid carrying two copies of the OXA-
24/40-like β-lactamase OXA-72. All 6 plasmids were identical at the
nucleotide level, while one isolate had a 5,845 bp region that was
reversed and flanked with XerC/XerD-like recombination sites. These
plasmids were only 3 SNPs different from a previously published
CRAB plasmid pAB120 (JX069966).
Conclusion: The combination of an established clinical laboratory
network and strong laboratory and epidemiology communication
helped identify a potential transmission route of this outbreak.
These data helped identify a long-term care facility in Wisconsin
(Facility C) as the connecting factor between Facility A and Facility
B. Here we demonstrate the value in using AST as a method of
prioritizing the use of valuable whole genome sequencing (WGS)
resources on potential outbreak isolates. The combination of long
read and short read WGS proved useful in the confirmation of
outbreak isolates and identification of a plasmid-borne OXA-72.
Assessing the Impact of the FDA Reclassification of Rapid
Antigen Influenza Diagnostic Tests (RIDT) in Wisconsin
E. Reisdorf, A. Bateman, M. Wedig and P. Shult, Wisconsin State
Laboratory of Hygiene
Background: In February 2017, a Food and Drug Administration
(FDA) final rule reclassifying RIDTs from class I to class II devices
with special controls to help improve the overall quality of testing for
influenza virus went into effect. We assessed the early impact of the
FDA reclassification on RIDT testing behavior and performance in
Wisconsin.
Methods: The Wisconsin State Laboratory of Hygiene (WSLH)
collects detailed clinical laboratory testing information along with
specimens submitted for respiratory pathogen surveillance from
sentinel sites. This includes the diagnostic testing kit used and test
results which are recorded in the laboratory information system. All
surveillance specimens received are tested for influenza by real-
time reverse transcription PCR (RT-PCR) (CDC Human Influenza
Virus Real-time RT-PCR Panel (IVD)). The WSLH RT-PCR results were
compared to those provided by the clinical laboratories to assess
the “real world” performance characteristics at multiple clinical
laboratories pre and post FDA reclassification. Data analysis was
performed from the 2012-2013 to the current 2018-2019 influenza
season. Performance of the RIDTs was assessed by determining the
percent discordant rates obtained with RT-PCR testing at the WSLH.
Results: Since the FDA reclassification, the number of different RIDT
tests used by clinical labs in Wisconsin has declined from 8 during
the 2015-2016 influenza season to 2 predominate tests (Quidel®
Sofia and BD VeritorTM) in 2018-2019 season. The number of RIDTs
reported were similar from season to season; however there has
been an increase in the number of rapid molecular tests performed.
The number of pre-screened RIDT surveillance specimens tested at
WSLH ranged from 220 to 1,120. The percent discordant rates for
all RIDTs specimens tested for the 2015-2016, 2016-2017, 2017-
2018 and 2018-2019 seasons were 11.8%, 8.8%, 10.3% and 10%
respectively. The discordant rates before the reclassification ranged
from 0% to 17.5% for those tests with >5 specimens tested by
RT-PCR at the WSLH. After reclassification, the percent discordant
ranges were 9.4% to 11.5% for the two RIDTs. Surprisingly, the
influenza test with the highest discordant rate for the 2016-2017,
2017-2018 and 2018-2019 seasons was not an immunoassay
RIDT, but a rapid molecular test.
Conclusions: The FDA reclassification of the RIDTs from class I to
class II devices may have had an impact by decreasing the number
of tests that were used by clinical laboratories in Wisconsin to two.
However, the overall performance of the RIDTs assessed by the
percent discordant rates compared with RT-PCR testing at WSLH
remained similar over the four influenza seasons that were analyzed
(pre and post reclassification). The diagnostic influenza test with
the highest discordant rate from the past three influenza seasons
was a rapid molecular assay which was not subject to the FDA
reclassification.
Presenter: Erik Reisdorf, Wisconsin State Laboratory of Hygiene,
Madison, WI, [email protected]
Presenter: Kelsey Florek, AR Fellow, Wisconsin State Laboratory
of Hygiene, Madison, WI, [email protected]
PublicHealthLabs
@APHL
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Summer 2019 LAB MATTERS
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