APHL 2019 POSTER ABSTRACTS
Background: Foodborne Diseases Active Surveillance Network
(FoodNet) conducts active laboratory-based surveillance for nine
enteric pathogens in 10 sites. Use of culture-independent diagnostic
tests (CIDTs) to diagnose enteric infections is increasing, including
highly sensitive multiplex polymerase chain reaction (PCR)-based
syndrome panels that can detect multiple pathogens from a single
specimen. Detection of multiple pathogens that could be the cause
of infection complicates case classification, cluster detection, and
treatment decisions. We describe polymicrobial detections (PDs)
and examine changes in their frequency.
Methods: We analyzed 2011-2017 FoodNet data on PDs that
included Campylobacter, Shiga toxin-producing Escherichia coli,
Listeria, Salmonella, Shigella, Vibrio, Yersinia, Cryptosporidium, or
Cyclospora. We defined a PD as detection of >1 pathogen, or >1
species or serotype by culture or CIDT in a single specimen or in
specimens collected <30 days apart. FoodNet has collected reports
of positive CIDTs for bacterial infections since 2012. We define a
case as a laboratory-diagnosed infection; thus, PDs are reported as
more than one case.
Results: During 2011-2017, we identified 1,693 persons with a
PD, resulting in 3,412 cases (2% of all cases reported to FoodNet).
PDs were identified in specimens collected on the same day for
1,384 (82%) persons, within 1–7 days for 158 (9%) persons, and
8–30 days for 151 (9%) persons. Among patients with PDs, 1,523
(90%) had pathogens of two genera, 139 (8%) had pathogens
of two species or sub-species, and 31 (2%) had ≥3 pathogens,
species, or sub-species. Campylobacter (64%) was the pathogen
most commonly detected in PDs, paired most often with Salmonella
(38%), Shigella (22%), and Cryptosporidium (17%). Among persons
with PDs, 1,204 (71%) were detected because one or both
pathogens were detected by CIDTs. Among these test results, by
person, 652 (54%) were solely PCR-based [381 (32%) syndrome
panels, 271 (22%) laboratory-developed], 382 (32%) solely antigen-
based, 91 (7%) unknown, and 79 (7%) multiple types. Average
annual incidence rates of PDs increased 129% in 2015─2017
compared with 2011─2013 (0.71 vs. 0.31 per 100,000 persons). A
reflex culture was performed on 403 (33%) of CIDT specimens with
a PD; more than one pathogen was found in 42%, only one in 41%,
and none in 17%.
Conclusions: The number of PDs has increased dramatically with
increasing use of CIDTs. More information on the sensitivity and
specificity of CIDTs, initial culture, and reflex culture would help
in making treatment decisions and informing interpretation of
surveillance results.
Presenter: Kelly Barrett, Centers for Disease Control and
Prevention, Atlanta, GA, [email protected]
The Recovery of Nontyphoidal Salmonella from
CIDT-positive Stool Specimens
K. Dillon, J. Hensley, A. Blackstock, E. Trees, J. Besser,
H. Carleton, A. Huang and A. Williams-Newkirk,
Centers for Disease Control and Prevention
BEST
POSTER
2019
Salmonella is estimated to cause 1.2 million illnesses,
23,000 hospitalizations, and 450 deaths each
year in the US. Clinical laboratories are adopting
culture-independent diagnostic tests (CIDTs) to
detect Salmonella and other pathogens in human stool. CIDTs are
problematic for public health surveillance networks like PulseNet
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because they do not yield the isolates required for surveillance,
subtyping, and outbreak detection. To maintain isolate availability,
minimize costs, and improve turnaround time, an optimized,
standard protocol for isolate recovery from CIDT-positive stool
specimens is needed. This study examined the impact of transport
media, transport temperature, plating media, and enrichment
media on the recovery of two Salmonella serovars from human
stool. Five stool samples from clinically healthy, anonymous donors
were homogenized and pooled to make 1 standard stool, which was
divided and spiked with either Salmonella enterica ser. Newport or
Oranienburg at 104, 103, 102 and 101. The study was divided into
3 phases to address variables associated with isolate recovery and
each phase. Within each phase, each combination of variables was
tested in triplicate at each spike level. Phase 1 identified optimal
transport temperature (4°C or 22°C), transport media (Cary-Blair
Transport Medium or Gram-Negative broth), and plating media
(Hektoen Enteric Agar or Xylose Lysine Deoxycholate Agar). Phase 2
assessed pathogen die-off in transit during warmer months and the
effectiveness of ice mitigation (22°C, 22°C + ice, 55°C, 55°C + ice,
and 78°C + ice). Phase 3 incorporated the results from the previous
phases and identified an optimal enrichment (Modified Semi-Solid
Rappaport Vassiliadis, Tetrathionate Broth, or Selenite Broth).
For Phase 1, Salmonella was successfully recovered in 144/144
attempts from spiked stools held at 22°C, while only 61/144
recovery attempts were successful at 4°C. Recovery rates did not
differ by serotype, transport time, plating media, or transport media.
For Phase 2, Salmonella was successfully recovered in 144/144
attempts from spiked stools held at all transport temperatures
except the 26/36 recovery attempts from those held at 55°C
without ice. For Phase 3, Salmonella was successfully recovered
in 270/270 attempts from spiked stools held in each enrichment.
Results from this study strongly support the transport of Salmonella
CIDT-positive stool specimens at 22°C to optimize isolate recovery,
even at low pathogen loads. Specimens transported during the
warmer months may need to be transported on ice while remaining
at 22°C before and after transport. Enrichment has much less
impact than transport temperature but may be necessary for
specimens with low levels of Salmonella.
Presenter: Katie Dillon, Centers for Disease Control and Prevention,
Atlanta, GA, [email protected]
The Future of US National Cryptosporidiosis Surveillance:
What Do 2016 NNDSS and CryptoNet Data Tell Us?
A. Perez 1 , M. Hlavsa 1 , S. Gleason 1 , H. Seabolt 1 , J. Murphy 1 , S.
Collier 1 , K. Fullerton 1 , L. Xiao 1 , D. Roellig 1 ; 1 Centers for Disease
Control and Prevention, 2 South China Agricultural University
Background: Cryptosporidium is the leading etiology of US
recreational water–associated outbreaks and a leading cause
of zoonotic outbreaks. At least 30 Cryptosporidium species have
been identified. Outside the United States, select species have
been associated with specific exposures. The species are generally
indistinguishable by traditional diagnostic methods; only molecular
methods can distinguish species. Cryptosporidium genotyping
historically has been limited to outbreak investigations; National
Notifiable Diseases Surveillance System (NNDSS) does not capture
exposure data. CDC formally launched CryptoNet in mid-2015 to
nationally and systematically collect genotyping and exposure data.
This is the first examination of NNDSS and CryptoNet data together.
Summer 2019 LAB MATTERS
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