Lab Matters Fall 2024 | Page 83

APHL 2024 POSTER ABSTRACTS

Results : Of the 10,250 outbreaks uploaded to CaliciNet , 10,036 ( 97.9 %) were associated with a single norovirus genotype , 116 ( 1.1 %) with multiple norovirus genotypes and 98 ( 1.0 %) with either astrovirus , sapovirus , or rotavirus . Person-to-person transmission ( 58.6 %) was the most frequently reported , followed by foodborne ( 13.4 %) and environmental / waterborne ( 0.4 %) transmission ; no transmission information was provided for 27.6 % of outbreaks . A majority of outbreaks occurred in long-term care facilities ( 60.8 %), followed by restaurants ( 11.9 %), schools / child-care facilities / camps ( 9.5 %) and hospitals ( 3.0 %). A majority of norovirus outbreaks ( 61.9 %) were associated with GII . 4 viruses ranging from 50 % to 71 % per season . These included GII . 4 New Orleans ( 17.4 %) between 2009-2012 , GII . 4 Sydney ( 42.5 %) between 2012-2022 and two other GII . 4 variants ( 1.9 %). GI . 3 ( 5.6 %) was the next prevalent genotype followed by GII . 6 ( 4.7 %) and GII . 2 ( 4.6 %). Of the 2,621 sporadic samples , almost half ( 49.7 %) were GII . 4 variants followed by GII . 6 ( 8.9 %) and GI . 3 ( 8.0 %). Complete polymerase and capsid sequence analysis showed limited evolution for a few genotypes , including GII . 4 Sydney , over the surveillance period as well as a new GII . 4 variant .

Conclusions : Data from 15 years of norovirus outbreak surveillance demonstrate the majority of outbreaks were caused by GII . 4 viruses co-circulating with frequently changing non-GII . 4 genotypes . Our sequence analysis shows evolution of noroviruses , with multiple new genotypes emerging and changes in GII . 4 viruses . In norovirus outbreaks , person-to-person transmission was the most frequently identified route of transmission followed by foodborne . Sporadic samples tended to follow the same genotype distribution as norovirus outbreaks . Continued surveillance will help guide future prevention measures including targeted interventions such as vaccinations .

Presenter : Leslie Barclay , gvm3 @ cdc . gov

Genome sequences of Listeria ivanovii from surveillance of cases reported in humans , 1987-2018

Z . Ende , C . Walters , S . Stroika , C . Lee , Z . Kucerova , Centers for Disease Control and Prevention

Background : Although Listeria monocytogenes is the primary driver of human illness and death by listeriosis , several Listeria species have been reported to cause disease in humans . Listeria ivanovii is one such species found primarily in ruminants like cattle , sheep and goats , which makes milk products a potential vehicle for foodborne spread to humans . Of public health relevance , L . ivanovii can result in similar clinical outcomes as L . monocytogenes , especially for pregnant women and immunocompromised individuals who are at greatest risk . However , underreporting of L . ivanovii may contribute to the limited understanding of clinical incidence .

Methods : PulseNet , the nationwide surveillance network for enteric pathogens , has included L . ivanovii in the reference genome database since the transition from pulsed-field gel electrophoresis ( PFGE ) to whole-genome sequencing ( WGS ) in 2018 . Furthermore , surveillance isolates sent to the National Listeria Reference Laboratory at the CDC provides an additional resource for monitoring non-monocytogenes cases . Understanding genetic features and comparing them to other species in the genus Listeria including L . monocytogenes , provides an expanded perspective on pathogens that cause listeriosis and threats to human health . To that aim , we used single-molecule sequencing with Pacific

Bioscience ( PacBio ) technology and Illumina MiSeq to sequence the genomes of L . ivanovii isolates sent to the CDC .

Results : Sequences were obtained from five L . ivanovii isolates received at the CDC between 1987 and 2018 . Three are of human origin and two are of unknown origin . Phylogenetic analysis of these L . ivanovii sequences compared to other prototypical sequences of food and animal origin demonstrated no apparent sequence segregation by source .

Conclusions : Assemblies from PacBio sequencing and a phylogenetic analysis of L . ivanovii species are valuable resources for understanding pathogenic infections in humans and will help understand the evolutionary relationships of pathogenic Listeria species .

Presenter : Zachary Ende , oit8 @ cdc . gov

Presence Vibrio Nucleic Acid in Spirulina-based Dietary Supplements Detected by the BIO-FIRE ® RITM0381153FILMARRAY ® Gastrointestinal Panel

E . Verbrugge 1 , C . Scull 2 , H . Hwang 1 , J . Haan 1 , D . Boxrud 3 , C . Lee 3 , S . Coleman 2 , K . Bauman 2 , C . Russell 2 , Minnesota Department of Health 1 , biomerieux 2 , Center for Disease Control and Prevention 3

The BIOFIRE ® FILMARRAY ® Gastrointestinal ( GI ) Panel uses nested , multiplex polymerase chain reaction ( PCR ) followed by melting curve analysis for the detection of nucleic acids from parasitic , viral and bacterial organisms . The GI Panel is intended for use as an aid in the diagnosis of patients with signs and / or symptoms of gastrointestinal infection and is meant to be used in conjunction with other clinical , laboratory and epidemiological data . Due to the nature of molecular tests such as the GI Panel , a detected result only requires the presence of nucleic acids , not viable organism . Public Health surveillance at the Minnesota Department of Health ( MDH ) identified a significant portion of individuals with positive Vibrio results from molecular tests that could not be confirmed by culture , symptom histories that did not align with an acute infection and no recent consumption of raw or undercooked seafood or contact with salt water . CDC , MDH and APHL explored a theory that the possible presence of Vibrio DNA was due to supplements to support “ gut health ” such as those containing spirulina . A study was performed to determine if spirulina supplements harbored Vibrio DNA that could be detected by the GI Panel .

Fourteen supplements were purchased from grocery or drug stores and tested in this evaluation ; 11 contained spirulina , one contained kelp , one contained red alga and one contained organic seaweed . All 14 supplements were suspended in molecular grade water and tested on the GI Panel . Testing of nine supplements containing spirulina and one containing red alga resulted in a Detected result for either or both Vibrio and Vibrio cholerae . Nucleic acid preparations of each supplement were tested with a real-time quantitative PCR ( qPCR ) assay targeting the rpoB gene of Vibrio spp . Six of the 14 supplements were positive with Cq values of 14 -21 . These six supplements were further tested using a digital droplet PCR ( ddPCR ) assay for the Vibrio recA gene to obtain an absolute quantification . Four of the six supplements tested gave concentrations of 6E + 05 to 1.5E + 06 copies / mL ( 3E + 06 to 7.5E + 06 copies / g ).

These data indicate that some supplements contain Vibrio DNA that is detectable by the GI Panel . Further studies are needed to