Lab Matters Fall 2024 | Page 64

APHL 2024 POSTER ABSTRACTS

Upon validating inactivation conditions , we will conduct studies to confirm that they do not adversely impact the ELISA assay performance on which these specimens will be performed . Inaccurate diagnostic results can lead to detrimental effects , such as underestimation of the seropositive rate in a local community .

Presenter : Ninecia Scott , tqf1 @ cdc . gov

DATA AND ANALYTICS

Analysis of Positive Clinical and Colonization Screening Data of AMR Isolates in Iowa .

K . Alvarez , M . Alvarez , State Hygienic Lab at the University of Iowa

MDROs are a major threat to the public health system . Therefore , prediction of outbreaks , infection control and evidence-based strategies for mitigation need to be developed . Antimicrobial resistant ( AMR ) infections can cause high rates of morbidity and mortality . Vulnerable populations for AMR infections are those that experience a long term stay at a hospital , rehab center , or reside at a long-term care facility . Screening and testing of colonized patients for AMR organisms serves several purposes including tracking resistance changes , identifying outbreaks and preventing future outbreaks . Analysis of this data is important to identify patterns and correlations between colonization screening and clinical cases , demonstrate the value of colonization screenings , recognize repeat and transmission cases and identify major mechanisms of resistance . This data has epidemiological value , guides development of new testing assays and workflows and may inform antimicrobial treatment options . Here , we analyzed clinical testing and colonization screening data to identify a correlation between the 2 data sets . This was done for both CRE , CRAB and C . auris positive clinical data and colonization screening data between 2017-2023 .

Presenter : Kanwal Alvarez , kanwal-alvarez @ uiowa . edu

Immunohistochemical Evaluation of Antigen Stability in Autopsy Tissues Infected with Free-living Amoebae .

A . Wong-Sam , P . Fair , J . Swims , H . Bullock , J . Ritter , J . Villalba , J . Kasten , R . Martines , Centers for Disease Control and Prevention

Central nervous system ( CNS ) infection by free-living amoebae ( FLA ) is rare but often fatal . Common FLA that infect the CNS are Acanthamoeba spp ., Balamuthia mandrillaris and Naegleria fowleri . Symptom onset following N . fowleri is usually rapid at 1-9 days post exposure while for Acanthamoeba spp . and B . mandrillaris may be weeks to months after exposure . Early diagnosis and treatment may increase survival . Immunohistochemistry ( IHC ) assays detect antigens in formalin-fixed , paraffin-embedded ( FFPE ) tissue sections mounted on glass slides and can be utilized for rapid diagnosis of infectious etiologies . Unstained paraffinized tissue slides may be damaged during storage at the pre-analytical stage , negatively affecting the quality of IHC results . The Centers for Disease Control and Prevention ( CDC ) has a Clinical Laboratory Improvement Amendments ( CLIA ) -approved amoeba IHC assay that detects Acanthamoeba spp ., B . mandrillaris and N . fowleri and is validated for use on unstained FFPE tissue slides if created within 10 days prior to submission of specimens to CDC . Here , we evaluated the effect of prolonged storage on the amoeba IHC assay performance to determine if the acceptable processing time could be extended , allowing for additional diagnostic opportunities for patients .

First , we retrospectively identified amoebae positive cell control tissues from 2014-2023 that were previously tested by the amoeba IHC after being stored in the dark at room temperature (“ routine storage ”). Immunoreactivity was graded by using a semiquantitative intensity scale ( 0-4 ). Intensity grades > 3 were considered immunoreactive ( IR ) and < 2 not IR . We identified 240 positive cell control tissues with storage duration ranging from 0 to 398 days ( median 49 , IQR 21-87 ). Of these , 237 were considered IR and 3 were considered not IR ( 25 , 58 , 96 days of storage ).

Next , we evaluated the immunoreactivity of unstained FFPE tissue slides from archival autopsy or necropsy cases tested after 6 years of routine storage . Fresh unstained tissue sections from 8 FFPE blocks with tissues previously IR for amoeba were tested sideby-side with stored unstained FFPE tissue slides from the same blocks . The order of fresh vs stored tissue sections was randomized for individual and side-by-side evaluation and pathologists were blinded to the age of the slides . All slides were considered IR and paired tissues sectioned from the same block had similar antigen distribution and IR intensity .

Antigen decay in unstained slides has been described in previous studies for several cell / tumor markers and 13 veterinary infectious disease ( ID ) agents . These preliminary results for the amoeba IHC assay demonstrate antigen stability under routine storage beyond 90 days and for up to 6 years for unstained slides with positive cell controls and archival case FFPE tissues , respectively . Our data suggest that unstained FFPE tissue slides with suspected freeliving amoebae infection can be tested via IHC assay after 10 days of creation prior to submission if routine storage conditions are maintained . Next steps include applying this methodology to IHC assays for over 30 additional human ID agents exposed to different storage conditions or prolonged routine storage . Results will be useful to optimize storage conditions to ensure quality of results across different pathogens , even in delayed testing scenarios .

Presenter : Andres Wong-Sam , pqk7 @ cdc . gov

Overview of the Department of Defense Global Respiratory Pathogen Surveillance Program : 2023-2024 Influenza Season

J . Thervil , L . DeMarcus , B . Kwaah , W . Jenkins , A . Bogue , W . Gruner , D . Muehleman , J . Hardy , A . Fries , J . Meyer , K . Lanter , K . Shaw , E . Macias , Defense Centers for Public Health – Dayton ( DCPH-D )

Introduction : For over a century , military populations have been significantly affected by respiratory diseases . In modern times , respiratory health events such as the 2009 influenza A ( H1N1 ) pdm09 pandemic and the COVID-19 pandemic continue to take place , highlighting the need for year-round respiratory pathogen surveillance in the Department of Defense ( DoD ). The DoD Global Respiratory Pathogen Surveillance Program ( DoDGRPSP ), a yearround , sentinel-based program funded by the Defense Health Agency ’ s Global Emerging Infections Surveillance ( GEIS ) branch , has broaden the mission and priorities of Project Gargle and conducts surveillance on influenza , SARS-CoV-2 and an array of non-influenza respiratory pathogens .