Lab Matters Summer 2018 | Page 60

APHL 2018 Annual Meeting Poster Abstracts

Food Safety recovery of YE from stools positive by the GI panel and subsequently to evaluate these isolates further using laboratory epidemiological methods for outbreak investigating .

Methods : Stools preserved in maintenance media that had YE detected by the GI panel were either directly cultured to CIN agar plates incubated at room temperature ( RT ) for up to 5 days or 500 µ l placed into sterile PBS ( 10 ml ) and incubated at 4 ° C ( cold enrichment ) for up to 2 weeks with incremental subcultures to CIN agar . Isolates detected from these stools were subsequently tested by pulsed-field gel electrophoresis ( PFGE ) using XbaI restriction enzyme and whole genome sequencing ( WGS ) ( Illumina MiSeq ). Cluster analysis of PFGE profiles and WGS single nucleotide polymorphism ( SNP ) analysis were performed using BioNumerics 7.6 .

Results : Twenty-six stools positive by the GI panel were cultured for YE . YE was recovered from 14 stools ( 53.8 %) following RT incubation and a total of 21 stools ( 80.1 %) following cold enrichment . Eighteen of these isolates were further evaluated using PFGE and WGS . Cluster analysis of PFGE patterns revealed high diversity among isolates ; however , four clusters ( 2-4 isolates in each ) of indistinguishable PFGE patterns , were observed . SNP analysis of the WGS of these 20 isolates also demonstrated similar results when compared to the PFGE patterns with most isolates found to be unrelated with > 200 SNPs among the isolates . Two of the four potential clusters from PFGE had WGS with ~ 180 SNPs identified between isolates in each cluster , suggesting that the isolates within these two clusters were not outbreak related . However , the isolates within the other two clusters showed no SNPs between them , suggesting that the isolates within each cluster were clonal .

Conclusion : This study showed that the addition of the cold enrichment method to routine culture improved recovery of YE . Results also showed the enhanced discriminatory processes of WGS when compared to PFGE for the assessment of YE strains . The enhanced discriminatory power of WGS did show that two clusters of yersiniosis may have occurred in 2016 although a majority of the isolates were unrelated . Additional epidemiological studies and further bioinformatic analysis of these YE cases are ongoing .

Presenter : Arryn Craney , University of Nebraska Medical Center , Omaha , NE , Nebraska Public Health Laboratory , Omaha , NE , Email : arryn . craney @ unmc . edu

Application of Matrix-Assisted Laser Desorption Ionization- Time of Flight ( MALDI-TOF ) Mass Spectrometry for Identification of Campylobacter jejuni in the Public Health Laboratory

M . Mash 1 , K . Levinson 2 , M . Miller 1 , S . Greene 1 , T . Lawson 1 ; 1 North Carolina State Laboratory of Public Health , Raleigh , NC , 2 UNC Hospitals , University of North Carolina , Chapel Hill

Introduction : Campylobacteriosis is a leading cause of diarrheal illness in the United States , with an estimated 1.3 million infections each year ( 1 ). Rapid identification of Campylobacter is critical to both public health outbreak investigation and surveillance as well as clinically , as it guides antimicrobial therapy and resistance testing . Matrix-Assisted Laser Desorption Ionization-Time of Flight ( MALDI-TOF ) Mass Spectrometry ( MS ) offers a time and cost-saving alternative to traditional culture methods that use selective media and biochemicals for organism identification . This study describes the verification of the Bruker ® MS for the identification of Camplylobacter jejuni and incorporation of MALDI-TOF mass spectrometry into the microbiology workflow in the public health laboratory .

Methods : C . jejuni was included in the Bruker ® FDA-cleared ( CA system ) reference database validation , thus the purpose of this study was to verify the Bruker ® MS for species-level organism identification of C . jejuni at the North Carolina State Laboratory of Public Health . Eight patient samples previously identified as C . jejuni via routine methods including Gram stain , microaerophilic culture on selective media and biochemicals including hippurate were used in the verification . Campylobacter coli was used as a Campylobacter spp . ( non-jejuni ) control and Escherichia coli was used as a non- Campylobacter control . Isolates were spotted in quadruplicate by two technologists and from two validated media types to assess accuracy and precision of the MS organism identification . All isolates included in this study had species identification confirmed by 16S rRNA gene sequencing ( reference method ).

Results : Among the isolates tested , 10 / 10 isolates were in agreement between 16S rRNA gene sequencing and the Bruker ® MS to the genus and species level . Among all spots tested on the Bruker ® MS , the mean log ( score ) value was 2.22 , correlating with a high confidence identification . We found that isolates were identified with a higher log ( score ) value when incubated for > 36hrs . 16S rRNA gene sequencing identified each isolate to the species level with ≥99 % sequence identity . The accuracy of analyzable results was 100 % ( 10 / 10 ).

Conclusion : Results from this verification support the use of Bruker ® MS in routine testing , as it correctly identified all C . jejuni isolates and was in 100 % agreement with the reference method ( 16S rRNA gene sequencing ). MALDI-TOF MS technology provides a rapid and accurate means of organism identification that once integrated in the public health laboratory , can substantially decrease turnaround time , labor and overall cost .

References : 1 . Centers for Disease Control and Prevention . Campylobacter : Information for Health Professionals . https :// www . cdc . gov / campylobacter / technical . html

Presenters : Kara Levinson , MPH , PhD , University of North Carolina , Chapel Hill , UNC Hospitals , Chapel Hill , NC , Phone : 984.974.1443 , Email : kara . Levinson @ unchealth . unc . edu and Michael Mash , MS , North Carolina State Laboratory of Public Health , Raleigh , NC , Phone : 919.807.8942 , Email : michael . mash @ dhhs . nc . gov

Application of Whole Genome Sequencing to an Outbreak of E . Coli O157 : H7 in a Rural Community in Utah and Arizona

K . Oakeson , Utah Public Health Laboratory , Taylorsville , UT

Shiga toxin-producing Escherichia coli subtypes , including Escherichia coli O157 : H7 are responsible for an estimated 265,000 infections and 30 deaths annually in the United States according to the Centers for Disease Control and Prevention . In July of 2017 , the Utah Department of Health and Utah Public Health Laboratory ( UPHL ) identified a cluster of E . coli O157 : H7 . During the course of the investigation , UPHL applied whole genome sequencing and molecular phylogenetic analysis to patient and environmental samples to aid in the investigation , to help identify the source of the outbreak and to help prevent further illness . In addition to routine whole genome sequencing ( WGS ) phylogeneticanalysis , metagenomic analyses were performed on a sub-set of samples , including samples that were positive of E . coli O157 : H7 via culture