scholarly journals 2356. Increased Clinical Specificity with Ultrasensitive Detection of Clostridioides difficile Toxins: Reduction of Overdiagnosis Compared with Nucleic Acid Amplification Tests

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S811-S812 ◽  
Author(s):  
Johanna Sandlund ◽  
Joel Estis ◽  
Phoebe Katzenbach ◽  
Niamh Nolan ◽  
Kirstie Hinson ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Disease Severity ◽  
Single Molecule ◽  
Clinical Performance ◽  
Neutralization Assay ◽  
Nucleic Acid Amplification ◽  
Clostridioides Difficile ◽  
Percent Agreement ◽  
Clostridioides Difficile Infection ◽  
Healthcare Associated

Abstract Background Clostridioides difficile infection (CDI) is one of the most common healthcare-associated infections, resulting in significant morbidity, mortality, and economic burden. Diagnosis of CDI relies on the assessment of clinical presentation and laboratory tests. We have evaluated the clinical performance of ultrasensitive Single Molecule Counting technology for detection of C. difficile toxins A and B. Methods Stool specimens from 298 patients with suspected CDI were tested with nucleic acid amplification test (NAAT; BD MAX™ Cdiff assay or Xpert® C. difficile assay) and Singulex Clarity® C. difficile toxins A/B assay. Specimens with discordant results were tested with cell cytotoxicity neutralization assay (CCNA), and results were correlated with disease severity and outcome. Results There were 64 NAAT-positive and 234 NAAT-negative samples. Of the 32 NAAT+/Clarity− and 4 NAAT-/Clarity+ samples, there were 26 CCNA− and 4 CCNA- samples, respectively. CDI relapse or overall death was more common in NAAT+/toxin+ patients than in NAAT+/toxin− and NAAT−/toxin− patients, and NAAT+/toxin+ patients were 3.7 times more likely to experience relapse or death (Figure 1). The clinical specificity of Clarity and NAAT was 97.4% and 89.0%, respectively, and overdiagnosis was over three times more common in NAAT+/toxin− than in NAAT+/toxin+ patients (Figure 2). Negative percent agreement between NAAT and Clarity was 98.3%, and positive percent agreement increased from 50.0% to effective 84.2% and 94.1% after CCNA testing and clinical assessment. Conclusion The Clarity assay was superior to NAATs in diagnosis of CDI, by reducing overdiagnosis and thereby increasing clinical specificity, and presence of toxins was associated with disease severity and outcome. Disclosures All authors: No reported disclosures.

scholarly journals Increased Clinical Specificity with Ultrasensitive Detection of Clostridioides difficile Toxins: Reduction of Overdiagnosis Compared to Nucleic Acid Amplification Tests

2019 ◽  
Vol 57 (11) ◽  
Author(s):  
Johanna Sandlund ◽  
Joel Estis ◽  
Phoebe Katzenbach ◽  
Niamh Nolan ◽  
Kirstie Hinson ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Patient Outcomes ◽  
Single Molecule ◽  
Clinical Performance ◽  
Neutralization Assay ◽  
Nucleic Acid Amplification ◽  
Content Type ◽  
Clostridioides Difficile ◽  
Health Care Associated Infections ◽  
Stool Specimens

ABSTRACT Clostridioides difficile infection (CDI) is one of the most common health care-associated infections, resulting in significant morbidity, mortality, and economic burden. Diagnosis of CDI relies on the assessment of clinical presentation and laboratory tests. We evaluated the clinical performance of ultrasensitive single-molecule counting technology for detection of C. difficile toxins A and B. Stool specimens from 298 patients with suspected CDI were tested with the nucleic acid amplification test (NAAT; BD MAX Cdiff assay or Xpert C. difficile assay) and Singulex Clarity C. diff toxins A/B assay. Specimens with discordant results were tested with the cell cytotoxicity neutralization assay (CCNA), and the results were correlated with disease severity and outcome. There were 64 NAAT-positive and 234 NAAT-negative samples. Of the 32 NAAT+/Clarity− and 4 NAAT−/Clarity+ samples, there were 26 CCNA− and 4 CCNA− samples, respectively. CDI relapse was more common in NAAT+/toxin+ patients than in NAAT+/toxin− and NAAT−/toxin− patients. The clinical specificity of Clarity and NAAT was 97.4% and 89.0%, respectively, and overdiagnosis was more than three times more common in NAAT+/toxin− than in NAAT+/toxin+ patients. The Clarity assay was superior to NAATs for the diagnosis of CDI, by reducing overdiagnosis and thereby increasing clinical specificity, and the presence of toxins was associated with negative patient outcomes.

scholarly journals Analytical and Clinical Comparison of Three Nucleic Acid Amplification Tests for SARS-CoV-2 Detection

2020 ◽  
Vol 58 (9) ◽  
Author(s):  
Elizabeth Smith ◽  
Wei Zhen ◽  
Ryhana Manji ◽  
Deborah Schron ◽  
Scott Duong ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Severe Acute Respiratory Syndrome ◽  
Drug Administration ◽  
Clinical Performance ◽  
Absolute Quantification ◽  
Nucleic Acid Amplification ◽  
Clinical Correlation ◽  
Molecular Assays ◽  
Percent Agreement ◽  
Rna Transcript

ABSTRACT Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first identified in December 2019 and has quickly become a worldwide pandemic. In response, many diagnostic manufacturers have developed molecular assays for SARS-CoV-2 under the Food and Drug Administration (FDA) Emergency Use Authorization (EUA) pathway. This study compared three of these assays, the Hologic Panther Fusion SARS-CoV-2 assay (Fusion), the Hologic Aptima SARS-CoV-2 assay (Aptima), and the BioFire Defense COVID-19 test (BioFire), to determine analytical and clinical performance as well as workflow. All three assays showed similar limits of detection (LODs) using inactivated virus, with 100% detection, ranging from 500 to 1,000 genome equivalents/ml, whereas use of a quantified RNA transcript standard showed the same trend but had values ranging from 62.5 to 125 copies/ml, confirming variability in absolute quantification of reference standards. The clinical correlation found that the Fusion and BioFire assays had a positive percent agreement (PPA) of 98.7%, followed by the Aptima assay at 94.7%, compared to the consensus result. All three assays exhibited 100% negative percent agreement (NPA). Analysis of discordant results revealed that all four samples missed by the Aptima assay had cycle threshold (Ct) values of >37 by the Fusion assay. In conclusion, while all three assays showed similar relative LODs, we showed differences in absolute LODs depending on which standard was employed. In addition, the Fusion and BioFire assays showed better clinical performance, while the Aptima assay showed a modest decrease in overall PPA. These findings should be kept in mind when making platform testing decisions.

scholarly journals Performance evaluation of the BD SARS-CoV-2 reagents for the BD MAX™ system

2021 ◽  
Author(s):  
Karen Yanson ◽  
William Laviers ◽  
Lori Neely ◽  
Elizabeth Lockamy ◽  
Luis Carlos Castillo-Hernandez ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Clinical Study ◽  
Nucleic Acid ◽  
Clinical Performance ◽  
Nucleic Acid Amplification ◽  
Standard Approach ◽  
Limits Of Detection ◽  
Percent Agreement ◽  
Post Market ◽  
Roche Cobas

Background Nucleic acid amplification testing (NAAT) for SARS-CoV-2 is the standard approach for confirming COVID-19 cases. This study compared results between two Emergency Use Authorization (EUA) NAATs, with two additional EUA NAATs utilized for discrepant testing. Methods The limits of detection (LOD) for the BD SARS-CoV-2 Reagents for BD MAX™ System (“MAX SARS-CoV-2 assay”), the Biomerieux BioFire® Respiratory Panel 2.1 (“BioFire SARS-CoV-2 assay”), the Roche cobas SARS-CoV-2 assay (“cobas SARS-CoV-2 assay”), and the Hologic Aptima® SARS-CoV-2 assay Panther® (“Aptima SARS-CoV-2 assay”) NAAT systems were determined using a total of 84 contrived nasopharyngeal specimens with seven target levels for each comparator. The positive and negative percent agreement (PPA and NPA, respectively) of the MAX SARS-CoV-2 assay, compared to the Aptima SARS-CoV-2 assay, was evaluated in a post-market clinical study utilizing 708 nasopharyngeal specimens collected from suspected COVID-19 cases. Discordant testing was achieved using cobas and BioFire SARS-CoV-2 NAATs. Results In this study, the measured LOD for the MAX SARS-CoV-2 assay (251 copies/mL; [95%CI: 186, 427]) was comparable to the cobas SARS-CoV-2 assay (298 copies/mL; [95%CI: 225, 509]) and the BioFire SARS-CoV-2 assay (302 copies/mL; [95%CI: 219, 565]); the Aptima SARS-CoV-2 assay had a LOD of 612 copies/mL; [95%CI: 474, 918]. The MAX SARS-CoV-2 assay had a PPA of 100% (95%CI: [97.3%-100.0%]) and a NPA of 96.7% (95%CI: [94.9%-97.9%]) when compared to the Aptima SARS-CoV-2 assay. Conclusions The clinical performance of the MAX SARS-CoV-2 assay agreed with another sensitive EUA assay.

scholarly journals A Bundled Approach to Reduce Delayed Testing and Hospital-Acquired Cases of Clostridioides difficile Infection

2020 ◽  
Vol 41 (S1) ◽  
pp. s92-s92
Author(s):  
Ioana Chirca ◽  
Alan Sun ◽  
Adrienne Wright Albrecht ◽  
Kelly Henry
Keyword(s):  
Developed Countries ◽  
Nucleic Acid Amplification ◽  
University Hospital ◽  
National Standard ◽  
Contact Precautions ◽  
The Third ◽  
Clostridioides Difficile ◽  
Clostridioides Difficile Infection ◽  
Healthcare Associated ◽  
The Impact

Background:Clostridioides difficile is a leading cause of nosocomial infectious diarrhea in developed countries, and it has a significant economic impact throughout the world. Early detection of the pathogen and its toxins is critical because early treatment significantly reduces infection-related morbidity, mortality, and medical cost. Surveillance of healthcare-associated infections (HAIs) is conducted using the NHSN standardized infection ratio (SIR). This metric allows comparison of a facility’s observed infection rate to a national benchmark. The SIR can be elevated due to both a lack of institutional criteria for stool submission and the use of highly sensitive but poorly specific testing as a standalone test for diagnosis. The SIR can be artificially elevated by inclusion of C difficile carriers rather than infected patients due to inappropriate testing and overly sensitive methods. We aimed to determine the impact of an institutional nursing-driven protocol for stool submission as well as 2-step testing on the SIR. Methods: Starting from the fourth quarter of 2018, we instituted a nursing protocol for initiation of C. difficile testing. If the patient had ≥3 soft, loose, or liquid stools in 24 hours within the first 3 days of admission, they were placed on contact precautions and an unformed stool sample was submitted for C. difficile nucleic acid amplification testing (NAAT). A positive result prompted further evaluation with a stool enzyme immunoassay toxin test for confirmation of active infection. From hospital day 4 onward, stricter criteria were implemented for testing for C. difficile infection. Data were extrapolated for calculation of a quarterly SIR. This value was then compared to retrospective SIR data from the first quarter of 2016 to the third quarter of 2018. Results: The quarterly total of hospital-onset C. difficile infections from the first quarter of 2016 to the third quarter of 2018 ranged from 24 to 39 incidents per quarter. After implementing the nursing-driven protocol and 2-step testing, the quarterly total of hospital onset C. difficile infections decreased to 5–6 per quarter. The SIR prior to initiation ranged from 0.66 to 1.37 and decreased to 0.306–0.386 after the nursing-driven protocol and 2-step testing were implemented. Conclusions: Implementation of both an institutional nursing-driven protocol for stool submission and a 2-step testing protocol reduced the number of quarterly hospital-onset C. difficile events as well as our facility’s quarterly SIR to below the national standard.Funding: NoneDisclosures: Ioana Chirca, University Hospital

Effect of testing methods on incidence of Clostridioides difficile infection rates in Veterans’ Affairs medical centers

2020 ◽  
pp. 1-3
Author(s):  
Brian P. McCauley ◽  
Martin E. Evans ◽  
Loretta A. Simbartl ◽  
Shantini D. Gamage ◽  
Stephen M. Kralovic ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Veterans Affairs ◽  
Nucleic Acid Amplification ◽  
Infection Rates ◽  
Testing Methods ◽  
Clostridioides Difficile ◽  
Medical Centers ◽  
Significant Difference ◽  
Clostridioides Difficile Infection ◽  
Veterans Affairs Medical Centers

Abstract Clostridioidesdifficile infection rates from 7 facilities that used nucleic acid amplification testing (NAAT) alone for 12 months then switched to NAAT plus toxin enzyme immunoassay (EIA) and reported the latter result for 12 months were compared to 70 facilities that used NAAT alone for all 24 months. There was no significant difference in rates between facility groups over the first 12 months (P = .21, linear regression), but we detected a decrease in rates for the facilities that changed to NAAT+EIA (P < .0001).

Evaluation of a nucleic acid amplification assay for the diagnosis of Clostridioides difficile infection

Anaerobe ◽  
2019 ◽  
Vol 59 ◽  
pp. 201-204
Author(s):  
Ozlem Koyuncu-Ozyurt ◽  
Betil Ozhak ◽  
Dilara Ogunc ◽  
Gozde Ongut ◽  
Filiz Gunseren ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acid Amplification ◽  
Clostridioides Difficile ◽  
Clostridioides Difficile Infection ◽  
Nucleic Acid Amplification Assay ◽  
Amplification Assay

scholarly journals Ultrasensitive Detection of Clostridioides difficile Toxins A and B by Use of Automated Single-Molecule Counting Technology

2018 ◽  
Vol 56 (11) ◽  
Author(s):  
Johanna Sandlund ◽  
Amelita Bartolome ◽  
Anna Almazan ◽  
Stanley Tam ◽  
Sheryl Biscocho ◽  
...  
Keyword(s):  
Single Molecule ◽  
Neutralization Assay ◽  
Cross Reactivity ◽  
Nucleic Acid Amplification ◽  
Analytical Sensitivity ◽  
Content Type ◽  
Testing Procedures ◽  
Clostridioides Difficile ◽  
A Cell ◽  
Stool Samples

ABSTRACT Current tests for the detection of Clostridioides (formerly Clostridium) difficile free toxins in feces lack sensitivity, while nucleic acid amplification tests lack clinical specificity. We have evaluated the Singulex Clarity C. diff toxins A/B assay (currently in development), an automated and rapid ultrasensitive immunoassay powered by single-molecule counting technology, for detection of C. difficile toxin A (TcdA) and toxin B (TcdB) in stool. The analytical sensitivity, analytical specificity, repeatability, and stability of the assay were determined. In a clinical evaluation, frozen stool samples from 311 patients with suspected C. difficile infection were tested with the Clarity C. diff toxins A/B assay, using an established cutoff value. Samples were tested with the Xpert C. difficile/Epi assay, and PCR-positive samples were tested with an enzyme immunoassay (EIA) (C. Diff Quik Chek Complete). EIA-negative samples were further tested with a cell cytotoxicity neutralization assay. The limits of detection for TcdA and TcdB were 0.8 and 0.3 pg/ml in buffer and 2.0 and 0.7 pg/ml in stool, respectively. The assay demonstrated reactivity to common C. difficile strains, did not show cross-reactivity to common gastrointestinal pathogens, was robust against common interferents, allowed detection in fresh and frozen stool samples and in samples after three freeze-thaw cycles, and provided results with high reproducibility. Compared to multistep PCR and toxin-testing procedures, the Singulex Clarity C. diff toxins A/B assay yielded 97.7% sensitivity and 100% specificity. The Singulex Clarity C. diff toxins A/B assay is ultrasensitive and highly specific and may offer a standalone solution for rapid detection and quantitation of free toxins in stool.

scholarly journals Analytical and Clinical Comparison of Three Nucleic Acid Amplification Tests for SARS-CoV-2 Detection

2020 ◽  
Author(s):  
Elizabeth Smith ◽  
Wei Zhen ◽  
Ryhana Manji ◽  
Deborah Schron ◽  
Scott Duong ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Severe Acute Respiratory Syndrome ◽  
Limit Of Detection ◽  
Clinical Performance ◽  
Absolute Quantification ◽  
Nucleic Acid Amplification ◽  
Clinical Correlation ◽  
Molecular Assays ◽  
Percent Agreement ◽  
Rna Transcript

AbstractSevere Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was first identified in December 2019 and has quickly become a worldwide pandemic. In response, many diagnostic manufacturers have developed molecular assays for SARS-CoV-2 under the Food and Drug Administration (FDA) Emergency Use Authorization (EUA) pathway. This study compared three of these assays: the Hologic Panther Fusion SARS-CoV-2 assay (Fusion), the Hologic Aptima SARS-CoV-2 assay (Aptima) and the BioFire Diagnostics COVID-19 test (BioFire), to determine analytical and clinical performance, as well as workflow. All three assays showed a similar limit of detection (LOD) using inactivated virus, with 100% detection ranging from 500-1,000 genome equivalents/ml, whereas use of a quantified RNA transcript standard showed the same trend, but had values ranging from 62.5 to 125 copies/ml, confirming variability in absolute quantification of reference standards. The clinical correlation found that the Fusion and BioFire assays had a positive percent agreement (PPA) of 98.7%, followed by the Aptima assay at 94.7% when compared to the consensus result. All three assays exhibited 100% negative percent agreement (NPA). Analysis of discordant results revealed that all four samples missed by the Aptima assay had Ct values >37 on the Fusion assay.In conclusion, while all three assays showed similar relative LODs, we showed differences in absolute LODs depending on which standard was employed. In addition, the Fusion and BioFire assays showed better clinical performance, while the Aptima assay showed a modest decrease in overall PPA. These findings should be kept in mind when making platform testing decisions.

scholarly journals 2352. Clinician Assessment of Pretest Probability for Clostridioides difficile Infection and Disease Severity While Using Multiplex, Syndromic Molecular Panel in Patients Presenting with Diarrhea

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S809-S809
Author(s):  
S Kyle Throneberry ◽  
Bert K Lopansri ◽  
Nancy A Grisel
Keyword(s):  
Disease Severity ◽  
Delayed Diagnosis ◽  
Antibiotic Use ◽  
Pretest Probability ◽  
Nucleic Acid Amplification ◽  
Molecular Testing ◽  
Clostridioides Difficile ◽  
Clostridioides Difficile Infection ◽  
Multiple Pathogens

Abstract Background The role of nucleic acid amplification tests (NAAT) for diagnosing Clostridioides difficile (CD) infection remains controversial. Adding CD to multiplex molecular panels (GIPCR) that detects multiple GI pathogens of community origin, has the potential to introduce confusion leading to delayed diagnosis and unnecessary antibiotic use especially if pretest probability is not considered. Methods We conducted a retrospective study to determine the frequency at which clinicians characterize pretest probability and disease severity in adult patients with diarrhea who tested positive for CD by GIPCR (BioFire, Inc.) from July 1, 2017 to October 16, 2018. We excluded immunocompromised patients. Routine testing includes reflex to GDH and toxin A/B detection when GIPCR is positive for CD. Charts were reviewed and clinical suspicion (PTP) was assigned as high, medium, low, or not done. Disease severity was classified as mild, moderate and severe. Exposure to systemic antibiotic within 90 days prior to testing and stool frequency was also captured. Results In total, 447 patients were included in the analysis: 110 (24.6%) were positive for both GDH and Toxin (G+/T+), 158 (35.3%) were G+/T−, 179 (40%) were G−/T−, and 149 (33%) were not classified. Toxin positivity was highest in the setting of high PTP (67%) (figure). In contrast, toxin was negative in most cases when suspicion for CDI was low or not characterized (81%). For medium suspicion, only 36% were T+. Antibiotic exposure prior to testing was observed in 203 (45%) of the cases. More G+/T+ patients received antibiotics (63%) before testing and 66% of G−/T− did not receive antecedent antibiotics. Clinicians did not characterize frequency of diarrhea in 261 (58%) of the patients tested and 95% of cases did not undergo severity classification. When documented, 24% of tested patients had < 3 diarrheal episodes/day (Table 1). Most cases where multiple pathogens were detected were T− (84.5%) and G−/T− (44%) (Table 2). Conclusion Overall, characterization of diarrheal illness was poor and PTP was frequently omitted. A large proportion of GIPCR results positive for CD (40%) were negative for both GDH and Toxin. CD results in molecular testing with syndromic panels should be interpreted with caution. Disclosures All authors: No reported disclosures.

scholarly journals Analysis of National Healthcare Safety Network Clostridioides difficile Infection Standardized Infection Ratio by Test Type

2020 ◽  
Vol 41 (S1) ◽  
pp. s116-s118
Author(s):  
Qunna Li ◽  
Andrea Benin ◽  
Alice Guh ◽  
Margaret A. Dudeck ◽  
Katherine Allen-Bridson ◽  
...  
Keyword(s):  
Risk Adjustment ◽  
Healthcare Facility ◽  
Directional Pattern ◽  
Incidence Rates ◽  
Nucleic Acid Amplification ◽  
Test Type ◽  
Clostridioides Difficile ◽  
Clostridioides Difficile Infection ◽  
The Mean ◽  
The Difference

Background: The NHSN has used positive laboratory tests for surveillance of Clostridioides difficile infection (CDI) LabID events since 2009. Typically, CDIs are detected using enzyme immunoassays (EIAs), nucleic acid amplification tests (NAATs), or various test combinations. The NHSN uses a risk-adjusted, standardized infection ratio (SIR) to assess healthcare facility-onset (HO) CDI. Despite including test type in the risk adjustment, some hospital personnel and other stakeholders are concerned that NAAT use is associated with higher SIRs than are EIAs. To investigate this issue, we analyzed NHSN data from acute-care hospitals for July 1, 2017 through June 30, 2018. Methods: Calendar quarters for which CDI test type was reported as NAAT (includes NAAT, glutamate dehydrogenase (GDH)+NAAT and GDH+EIA followed by NAAT if discrepant) or EIA (includes EIA and GDH+EIA) were selected. HO CDI SIRs were calculated for facility-wide inpatient locations. We conducted the following analyses: (1) Among hospitals that did not switch their test type, we compared the distribution of HO incident rates and SIRs by those reporting NAAT vs EIA. (2) Among hospitals that switched their test type, we selected quarters with a stable switch pattern of 2 consecutive quarters of each of EIA and NAAT (categorized as pattern EIA-to-NAAT or NAAT-to-EIA). Pooled semiannual SIRs for EIA and NAAT were calculated, and a paired t test was used to evaluate the difference of SIRs by switch pattern. Results: Most hospitals did not switch test types (3,242, 89%), and 2,872 (89%) reported sufficient data to calculate SIRs, with 2,444 (85%) using NAAT. The crude pooled HO CDI incidence rates for hospitals using EIA clustered at the lower end of the histogram versus rates for NAAT (Fig. 1). The SIR distributions of both NAAT and EIA overlapped substantially and covered a similar range of SIR values (Fig. 1). Among hospitals with a switch pattern, hospitals were equally likely to have an increase or decrease in their SIR (Fig. 2). The mean SIR difference for the 42 hospitals switching from EIA to NAAT was 0.048 (95% CI, −0.189 to 0.284; P = .688). The mean SIR difference for the 26 hospitals switching from NAAT to EIA was 0.162 (95% CI, −0.048 to 0.371; P = .124). Conclusions: The pattern of SIR distributions of both NAAT and EIA substantiate the soundness of NHSN risk adjustment for CDI test types. Switching test type did not produce a consistent directional pattern in SIR that was statistically significant.Disclosures: NoneFunding: None

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