Performance evaluation of the high-throughput quantitative Alinity m BK virus assay.

BK virus (BKV) infection or reactivation in immunocompromised individuals can lead to adverse health consequences including BKV-associated nephropathy (BKVAN) in kidney transplant patients and BKV-associated hemorrhagic cystitis (BKV-HC) in allogeneic hematopoietic stem cell transplant recipients. Monitoring BKV viral load plays an important role in post-transplant patient care. This study evaluates the performance of the Alinity m BKV Investigational Use Only (IUO) assay. The linearity of the Alinity m BKV IUO assay had a correlation coefficient of 1.000 and precision of SD ≤ 0.25 Log IU/mL for all panel members tested (2.0-7.3 Log IU/mL). Detection rate at 50 IU/mL was 100%. Clinical plasma specimens tested comparing Alinity m BKV IUO to ELITech MGB Alert BKV lab-developed test (LDT) on the Abbott m2000 platform using specimen extraction protocols for DNA or total nucleic acid (TNA) resulted in coefficient of correlation of 0.900 and 0.963, respectively, and mean bias of 0.03 and -0.54 Log IU/mL, respectively. Alinity m BKV IUO compared with Altona RealStar BKV and Roche cobas BKV assays demonstrated coefficient of correlation of 0.941 and 0.980, respectively, and mean bias of -0.47 and -0.31 Log IU/mL, respectively. Urine specimens tested on Alintiy m BKV IUO and ELITech BKV LDT using TNA specimen extraction had a coefficient of correlation of 0.917 and mean bias of 0.29 Log IU/mL. The Alinity m BKV IUO assay was performed with high precision across the dynamic range and correlated well with other available BKV assays. IMPORTANCE: BK virus (BKV) in transplant patients can lead to adverse health consequences. Viral load monitoring is important in post-transplant patient care. This study evaluates the Alinity m BKV assay with currently available assays.

Clinical Performance of the Novel GenMark Dx ePlex Blood Culture ID Gram-Positive Panel.

Rapid identification from positive blood cultures is standard of care (SOC) in many clinical microbiology laboratories. The GenMark Dx ePlex Blood Culture Identification Gram-Positive (BCID-GP) Panel is a multiplex nucleic acid amplification assay based on competitive DNA hybridization and electrochemical detection using eSensor technology. This multicenter study compared the investigational-use-only (IUO) BCID-GP Panel to other methods of identification of 20 Gram-positive bacteria, four antimicrobial resistance genes, and both Pan Candida and Pan Gram-Negative targets that are unique to the BCID-GP Panel. Ten microbiology laboratories throughout the United States collected residual, deidentified positive blood culture samples for analysis. Five laboratories tested both clinical and contrived samples with the BCID-GP Panel. Comparator identification methods included each laboratory's SOC, which included matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and automated identification systems as well as targeted PCR/analytically validated real-time PCR (qPCR) with bidirectional sequencing. A total of 2,342 evaluable samples (1,777 clinical and 565 contrived) were tested with the BCID-GP Panel. The overall sample accuracy for on-panel organisms was 89% before resolution of discordant results. For pathogenic Gram-positive targets (Bacillus cereus group, Enterococcus spp., Enterococcus faecalis, Enterococcus faecium, Staphylococcus spp., Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Listeria spp., Listeria monocytogenes, Streptococcus spp., Streptococcus agalactiae, Streptococcus anginosus group, Streptococcus pneumoniae, and Streptococcus pyogenes), positive percent agreement (PPA) and negative percent agreement (NPA) ranged from 93.1% to 100% and 98.8% to 100%, respectively. For contamination rule-out targets (Bacillus subtilis group, Corynebacterium, Cutibacterium acnes, Lactobacillus, and Micrococcus), PPA and NPA ranged from 84.5% to 100% and 99.9% to 100%, respectively. Positive percent agreement and NPA for the Pan Candida and Pan Gram-Negative targets were 92.4% and 95.7% for the former and 99.9% and 99.6% for the latter. The PPAs for resistance markers were as follows: mecA, 97.2%; mecC, 100%; vanA, 96.8%; and vanB, 100%. Negative percent agreement ranged from 96.6% to 100%. In conclusion, the ePlex BCID-GP Panel compares favorably to SOC and targeted molecular methods for the identification of 20 Gram-positive pathogens and four antimicrobial resistance genes in positive blood culture bottles. This panel detects a broad range of pathogens and mixed infections with yeast and Gram-negative organisms from the same positive blood culture bottle.

Molecular point-of-care testing for influenza A/B and respiratory syncytial virus: comparison of workflow parameters for the ID Now and cobas Liat systems.

AIMS: Point-of-care (POC) tests for influenza and respiratory syncytial virus (RSV) offer the potential to improve patient management and antimicrobial stewardship. Studies have focused on performance; however, no workflow assessments have been published comparing POC molecular tests. This study compared the Liat and ID Now systems workflow, to assist end-users in selecting an influenza and/or RSV POC test. METHODS: Staffing, walk-away and turnaround time (TAT) of the Liat and ID Now systems were determined using 40 nasopharyngeal samples, positive for influenza or RSV. The ID Now system requires separate tests for influenza and RSV, so parallel (two instruments) and sequential (one instrument) workflows were evaluated. RESULTS: The ID Now ranged 4.1-6.2 min for staffing, 1.9-10.9 min for walk-away and 6.4-15.8 min for TAT per result. The Liat ranged 1.1-1.8 min for staffing, 20.0-20.5 min for walk-away and 21.3-22.0 min for TAT. Mean walk-away time comprised 38.0% (influenza positive) and 68.1% (influenza negative) of TAT for ID Now and 93.7% (influenza/RSV) for Liat. The ID Now parallel workflow resulted in medians of 5.9 min for staffing, 9.7 min for walk-away and 15.6 min for TAT. Assuming prevalence of 20% influenza and 20% RSV, the ID Now sequential workflow resulted in medians of 9.4 min for staffing, 17.4 min for walk-away, and 27.1 min for TAT. CONCLUSIONS: The ID Now and Liat systems offer different workflow characteristics. Key considerations for implementation include value of both influenza and RSV results, clinical setting, staffing capacity, and instrument(s) placement.

Multicenter Evaluation of the Bruker MALDI Biotyper CA System for the Identification of Clinically Important Bacteria and Yeasts.

OBJECTIVES: A report on the multicenter evaluation of the Bruker MALDI Biotyper CA System (MBT-CA; Bruker Daltonics, Billerica, MA) for the identification of clinically important bacteria and yeasts. METHODS: In total, 4,399 isolates of medically important bacteria and yeasts were assessed in the MBT-CA. These included 2,262 aerobic gram-positive (AGP) bacteria, 792 aerobic gram-negative (AGN) bacteria 530 anaerobic (AnA) bacteria, and 815 yeasts (YSTs). Three processing methods were assesed. RESULTS: Overall, 98.4% (4,329/4,399) of all bacterial and yeast isolates were correctly identified to the genus and species/species complex level, and 95.7% of isolates were identified with a high degree of confidence. The percentage correctly identified and the percentage identified correctly with a high level of confidence, respectively, were as follows: AGP bacteria (98.6%/96.5%), AGN bacteria (98.5%/96.8%), AnA bacteria (98.5%/97.4%), and YSTs (97.8%/87.6%). The extended direct transfer method was only minimally superior to the direct transfer method for bacteria (89.9% vs 86.8%, respectively) but significantly superior for yeast isolates (74.0% vs 48.9%, respectively). CONCLUSIONS: The Bruker MALDI Biotyper CA System accurately identifies most clinically important bacteria and yeasts and has optional processing methods to improve isolate characterization.

Preliminary Evaluation of the Research-Use-Only (RUO) iCubate iC-GPC Assay for Identification of Select Gram-Positive Bacteria and Their Resistance Determinants in Blood Culture Broths.

The iC-GPC assay (iCubate, Huntsville, AL) provides a molecular option for the rapid, on-demand analysis of positive blood cultures. A preliminary evaluation of the iC-GPC assay using 203 clinical or seeded specimens demonstrated a sensitivity of 93.8% to 100% and a specificity of 98.0% to 100% for the identification of five Gram-positive bacterial species (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Enterococcus faecalis, and Enterococcus faecium) and three associated genetic resistance determinants (mecA, vanA, and vanB) in positive blood culture broths.