Lab Matters Fall 2024 | Page 74

APHL 2024 POSTER ABSTRACTS

effort . Incorporating SuperCarba and CARBA 5 in our isolate and colonization screening algorithms will streamline our workflows and lead to less hands-on processing time , decreased turnaround time and less cost .

Presenter : Saba Shama , Saba . Shama @ slh . wisc . edu

Improved Quality Control for Molecular-based Sepsis Diagnostics Testing with Patient-like Full-process Controls

V . Omidvar , S . Cossette , C . Cambridge , B . White , C . Connelly , Streck

While automated DNA-based sepsis tests have simplified molecular diagnostic workflows , the integration of multiple complex sample processing steps into a proverbial “ black box ” creates the potential for variability in instrument and test performance for these qualitative tests . With the increased adoption of molecular assays for diagnostic purposes , it is also essential that quality control measures evolve with the field and effectively identify anomalies within these systems . Because many current commercially available controls are comprised of synthetic materials or intact organisms that have been diluted in buffers , they fail to comprehensively measure the assay , as the formulations render the control insufficient to detect all panel targets and / or verify the system ’ s ability to process and remove sample matrix effects from inhibitors in patient blood and culture media . Manufacturer-provided internal controls , while an effective “ in-process ” QC step , are also inadequate because they also do not verify detection of all panel targets and cannot effectively evaluate matrix inhibition if the quality control matrix doesn ’ t reflect a patient sample . Gaps in coverage left by current quality control methods become a major issue when pathogen identification is critical . For example , a recent medical device correction for the BIOFIRE Blood Culture Identification 2 ( BCID2 ) Panel identified misdetection of C . tropicalis by a commercially available quality control kit that employs synthetic DNA targets . Errors such as this can lead to failed QC testing that delays patient sample analysis and ultimately patient care .

We propose a shift from “ traditional ” quality control designs to use of controls mirroring patient samples in composition and test experience . Patient-like , full-process controls are essential to adequately evaluate system and test performance , including manufacturer changes to the assay .

Here , we present MDx-Chex for BCID2 , MDx-Chex for BC-GP and MDx-Chex for BC-GN , quality control solutions for routine molecular diagnostic sepsis testing . These FDA-cleared , class II assayed , patient-like full process controls are intended for use with BIOFIRE BCID2 Panel and Luminex VERIGENE BC-GP and BC-GN sepsis panels , respectively . MDx-Chex controls contain intact , inactivated microorganisms constituted in a matrix representative of a blood culture sample . MDx-Chex for BCID2 data demonstrate overall precision and reproducibility of ≥ 95 % positive agreement ( n = 120 total tests , 95 % CI ) and ≥ 96 % positive agreement ( n = 240 , 95 % CI ), respectively and ≥ 99 % negative agreement . MDx- Chex for BC-GP and BC-GN data demonstrate 100 % positive and negative agreement ( n = 150 total tests , 95 % CI ) and ≥ 98 % positive agreement and 100 % negative agreement , respectively ( n = 150 total tests , 95 % CI ). Collectively , MDx-Chex controls ensure reliable and accurate BIOFIRE BCID2- and VERIGENE BC-GP and BC-GN panel-based sepsis testing , enabling physicians and healthcare professionals to maintain assay quality while improving compliance with accrediting standards and guidelines .

Presenter : Chris Connelly , cconnelly @ streck . com

In the Jungle , Welcome to the Fungal – Hologic Panther ’ s ® Got What You Need

M . Ahmann , J . Benfer , University of Iowa

Candida auris is an emerging resistant yeast that can cause severe infections and is easily spread , especially among healthcare facilities . The yeast was first identified in Japan in 2009 and has since displayed increased resistance to common antifungal medications at an alarming rate . Many traditional phenotypic methods for yeast identification misidentify C . auris as another yeast species . MALDI-TOF can accurately detect C . auris . However , this requires subculturing an original sample before MALDI-TOF use , which increases labor , turn-around time and is prohibitive for highvolume testing . Here , we describe the process for developing and optimizing a laboratory-developed assay ( LDA ) for C . auris detection by PCR on the fully automated Hologic Panther Fusion ® Open Access™ system .

Initially , a risk assessment and viability study were conducted to ensure laboratory safety during protocol development . For optimization , various concentrations of select reagents in a primer probe mix were evaluated following Open Access™ training recommendations . Validation was accomplished using positive and negative C . auris samples previously characterized by MALDI-TOF to assess accuracy , precision , sensitivity and specificity .

The LDA was successfully optimized and CLIA validated as a diagnostic test for epidemiological outbreak investigation and colonization screening . All methods outlined in this poster for developing an LDA using the Hologic Panther Fusion ® Open Access™ system are great resources to help prepare public health laboratories for increased testing volume and to improve current workflows . The system ’ s automated extraction reduces labor and turn-around time and increases reproducibility of results . Furthermore , samples do not require additional diagnostic confirmation due to high specificity for C . auris , enhancing convenience of results . These methods can be easily applied to the rapid development and optimization of LDAs for numerous pathogens of public health significance .

Presenter : Megan Ahmann , megan-ahmann @ uiowa . edu

Laboratory Evaluation of Three Rapid Syphilis Tests Using Sera From a High Prevalence Population Of MSM and TGW

M . Shukla 1 , K . Herrell 1 , K . Butler 1 , K . Pettus 1 , Y . Fakile 1 , A . Seña 2 , E . Kersh 1 , W . Cao 1 , Centers for Disease Control and Prevention 1 , University of North Carolina at Chapel Hill 2

Background : Syphilis is a multistage disease caused by a spirochete bacterium , Treponema pallidum subspecies pallidum . The laboratory diagnosis of syphilis is challenging and still relies on serological tests that detect treponemal and nontreponemal antibodies . In addition to laboratory based serological tests , there are only a handful of rapid syphilis tests currently available in the United States and performance data are limited . We conducted a