scholarly journals Performing Reflexive Toxin A/B Enzyme Immunoassay in a Two-Step Algorithm for the Diagnosis of Clostridium difficile Infection Has Limited Clinical Utility

2018 ◽  
Author(s):  
M Mounajjed ◽  
R Pease ◽  
B Jung-Hynes ◽  
N Safdar ◽  
D Chen
Keyword(s):  
Clostridium Difficile ◽  
Enzyme Immunoassay ◽  
Electronic Medical Records ◽  
Medical Records ◽  
Clinical Utility ◽  
Nucleic Acid Amplification ◽  
Toxin B ◽  
Clinical Sensitivity ◽  
Stool Samples ◽  
Step Algorithm

ABSTRACTThe differentiation of Clostridium difficile infection (CDI) from colonization is challenged by the suboptimal clinical specificity of nucleic acid amplification tests (NAAT). In this study, we examined the utility of testing for toxin via enzyme immunoassay (EIA) in specimens already tested by NAAT for the diagnosis of CDI in an attempt to differentiate colonization from infection. We tested 59 stool samples for the presence of C. difficile toxin B gene by NAAT followed by EIAs for glutamate dehydrogenase (GDH EIA) and toxins A and B (Toxin EIA). Two infectious disease physicians independently reviewed the patients’ electronic medical records retrospectively to categorize each patient as CDI-Likely, CDI-Unlikely, or CDI-Indeterminate. Clinical sensitivities and specificities were calculated using 3 definitions of “true” CDI status, being: (1) concordance between both reviewers, (2) concordance, and CDI-Indeterminate/discordant cases classified as CDI-Likely, and (3) concordance, and CDI-Indeterminate/discordant cases classified as CDI-Unlikely. Based on these definitions, clinical sensitivity and specificity for NAAT was 100% and 49-94%, GDH EIA was 83-85% and 43-89%, and Toxin EIA was 39-42% and 83-100%, respectively. 85% (22 of 26) of patients who were NAAT-positive but Toxin EIA-negative symptomatically benefited from treatment for CDI. The addition of EIA to NAAT for CDI diagnosis had limited utility for differentiating colonization from CDI and could have led to under treatment of patients with CDI.

scholarly journals Nucleic Acid Amplification Test Quantitation as Predictor of Toxin Presence in Clostridium difficile Infection

2017 ◽  
Vol 56 (3) ◽  
Author(s):  
M. J. T. Crobach ◽  
N. Duszenko ◽  
E. M. Terveer ◽  
C. M. Verduin ◽  
E. J. Kuijper
Keyword(s):  
Nucleic Acid ◽  
Clostridium Difficile ◽  
Characteristic Curve ◽  
Nucleic Acid Amplification Test ◽  
Nucleic Acid Amplification ◽  
Toxin A ◽  
Toxin B ◽  
Content Type ◽  
Quantitative Results ◽  
Testing Algorithm

ABSTRACT Multistep algorithmic testing in which a sensitive nucleic acid amplification test (NAAT) is followed by a specific toxin A and toxin B enzyme immunoassay (EIA) is among the most accurate methods for Clostridium difficile infection (CDI) diagnosis. The obvious shortcoming of this approach is that multiple tests must be performed to establish a CDI diagnosis, which may delay treatment. Therefore, we sought to determine whether a preliminary diagnosis could be made on the basis of the quantitative results of the first test in algorithmic testing, which provide a measure of organism burden. To do so, we retrospectively analyzed two large collections of samples ( n = 2,669 and n = 1,718) that were submitted to the laboratories of two Dutch hospitals for CDI testing. Both hospitals apply a two-step testing algorithm in which a NAAT is followed by a toxin A/B EIA. Of all samples, 208 and 113 samples, respectively, tested positive by NAAT. Among these NAAT-positive samples, significantly lower mean quantification cycle ( C q ) values were found for patients whose stool eventually tested positive for toxin, compared with patients who tested negative for toxin (mean C q values of 24.4 versus 30.4 and 26.8 versus 32.2; P < 0.001 for both cohorts). Receiver operating characteristic curve analysis was performed to investigate the ability of C q values to predict toxin status and yielded areas under the curve of 0.826 and 0.854. Using the optimal C q cutoff values, prediction of the eventual toxin A/B EIA results was accurate for 78.9% and 80.5% of samples, respectively. In conclusion, C q values can serve as predictors of toxin status but, due to the suboptimal correlation between the two tests, additional toxin testing is still needed.

scholarly journals Clostridium difficile Laboratory Identification Event Reporting – A Need for Diagnostic Stewardship

2017 ◽  
Vol 4 (suppl_1) ◽  
pp. S398-S399
Author(s):  
Clare Rock ◽  
Zoi Pana ◽  
Surbhi Leekha ◽  
Polly Trexler ◽  
Jennifer Andonian ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Medical Records ◽  
Chart Review ◽  
Nucleic Acid Amplification ◽  
Event Reporting ◽  
Laxative Use ◽  
Academic Center ◽  
The Us ◽  
Clinically Significant ◽  
Present On Admission

Abstract Background Clostridium difficile LabID event reporting uses electronic laboratory results without chart review. Nucleic acid amplification testing is common in the US. A positive result may represent colonization or C. diff infection (CDI). We review C.difflabID events to ascertain if Hospital-Onest CDI (HO CDI). For non-HO CDI, we identify reason and use a matrix to prioritize clinical areas for intervention efforts. Methods Each C. difflab ID event from Jan 2015 to June 2016 at academic center had chart review for HO CDI; defined significant diarrhea, not present on admission, with no laxatives in prior 48 hours. For non HO-CDI events, reason and receipt of antibiotic treatment within 14 days of the positive test were retrospectively noted. A prioritization matrix, where clinical services were ranked according to number of lab ID events (service’s contribution to the facility C. diffLabID), was multiplied by a rank based on percent of inappropriate tests giving an overall prioritization score for where intervention resources could potentially best be used. Results There were 490 C difficile LabID events; 284 (58%) were HO-CDI; 206 (42%) were inappropriate or delayed testing. Of the 190 with available medical records at time of retrospective review, reasons for not meeting the HO-CDI included laxative use within the previous 48 hours (41%), no clinically significant diarrhea (49.5%); delayed testing (9.5%). See figure. Of 172 patients with inappropriate testing, 159 (92%) were treated for CDI. Medicine and psychiatry ranked first and second on prioritization matrix. See table. Conclusion Nearly half of C. diff LabID events were not true HO CDI, but inappropriate or delayed tests. Prioritization matrix identified medicine and psychiatry as areas where diagnostic stewardship interventions could affect most on facility C. diff LabID. Disclosures K. C. Carroll, GenePOC, Inc.: Grant Investigator, Grant recipient

scholarly journals Development and Validation of Digital Enzyme-Linked Immunosorbent Assays for Ultrasensitive Detection and Quantification of Clostridium difficile Toxins in Stool

2015 ◽  
Vol 53 (10) ◽  
pp. 3204-3212 ◽  
Author(s):  
Linan Song ◽  
Mingwei Zhao ◽  
David C. Duffy ◽  
Joshua Hansen ◽  
Kelsey Shields ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Cytotoxicity Assay ◽  
Nucleic Acid Amplification ◽  
Analytical Sensitivity ◽  
Toxin B ◽  
Content Type ◽  
Toxigenic Culture ◽  
Immunosorbent Assays ◽  
Digital Elisa ◽  
Detection And Quantification

The currently available diagnostics forClostridium difficileinfection (CDI) have major limitations. Despite mounting evidence that toxin detection is paramount for diagnosis, conventional toxin immunoassays are insufficiently sensitive and cytotoxicity assays too complex; assays that detect toxigenic organisms (toxigenic culture [TC] and nucleic acid amplification testing [NAAT]) are confounded by asymptomatic colonization by toxigenicC. difficile. We developed ultrasensitive digital enzyme-linked immunosorbent assays (ELISAs) for toxins A and B using single-molecule array technology and validated the assays using (i) culture filtrates from a panel of clinicalC. difficileisolates and (ii) 149 adult stool specimens already tested routinely by NAAT. The digital ELISAs detected toxins A and B in stool with limits of detection of 0.45 and 1.5 pg/ml, respectively, quantified toxins across a 4-log range, and detected toxins from all clinical strains studied. Using specimens that were negative by cytotoxicity assay/TC/NAAT, clinical cutoffs were set at 29.4 pg/ml (toxin A) and 23.3 pg/ml (toxin B); the resulting clinical specificities were 96% and 98%, respectively. The toxin B digital ELISA was 100% sensitive versus cytotoxicity assay. Twenty-five percent and 22% of the samples positive by NAAT and TC, respectively, were negative by the toxin B digital ELISA, consistent with the presence of organism but minimal or no toxin. The mean toxin levels by digital ELISA were 1.5- to 1.7-fold higher in five patients with CDI-attributable severe outcomes, versus 68 patients without, but this difference was not statistically significant. Ultrasensitive digital ELISAs for the detection and quantification of toxins A and B in stool can provide a rapid and simple tool for the diagnosis of CDI with both high analytical sensitivity and high clinical specificity.

scholarly journals Clostridium difficile Testing Algorithm: Is There a Difference in Patients Who Test Positive by Enzyme Immunoassay vs. Those Who Only Test Positive by Nucleic Acid Amplification Methodology?

2017 ◽  
Vol 4 (suppl_1) ◽  
pp. S394-S394
Author(s):  
Jonathan Polak ◽  
Ogheneruona Odili ◽  
Mary Ashleigh Craver ◽  
Anthony Mayen ◽  
Kyle Purrman ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Clostridium Difficile ◽  
Length Of Stay ◽  
Enzyme Immunoassay ◽  
Serum Lactate ◽  
Nucleic Acid Amplification ◽  
Categorical Variables ◽  
Grant Recipient ◽  
Stool Specimens ◽  
Chi Square Analysis

Abstract Background Testing for Clostridium difficile infection (CDI) commonly involves checking for the presence of toxins A and B by enzyme immunoassay (EIA) or nucleic acid amplification (NAA). The former is very specific, but not very sensitive. The latter is very sensitive. Beginning in 2011, our hospital incorporated an algorithm that involved testing liquid stool specimens for glutamate dehydrogenase (GDH) and toxin by EIA. For discrepant results, the stool specimen was tested for the presence of toxin by NAA. We sought to determine whether there was a difference in the baseline characteristics or outcomes between the two groups. Methods We performed a chart review of all subjects who tested positive for CDI by either method between 2011 and 2016 at Vidant Medical Center, a 909 bed, tertiary care teaching hospital. Testing was only performed on liquid stool specimens. Subjects less than 18 years of age were excluded. Repeat positive specimens were excluded. We collected demographic data including age, gender, baseline temperature, white blood cell count, and serum lactate and albumin. Length of stay and in-hospital mortality were also determined for both groups. Comparison of the two groups was done using t-test for continuous and chi-square analysis for categorical variables. Results Over the 6 year period, there were 535 positive test results. 243 specimens tested positive by EIA/GDH (EIA +); 292 specimens tested positive by GDH/NAA (NAA +). Compared with the EIA + group, the NAA + group was younger (61.8 years vs. 65.1 years, P = 0.01). There were no statistical differences in the presence of abdominal tenderness, temperature &gt;38oC, serum albumin, serum lactate, length of stay, or mortality between the two groups. The EIA + group was statistically more likely to have leukocytosis (WBC &gt;20,000 cells/mm3) at the time of the CDI testing compared with the NAA + group (P = 0.0002). Conclusion There do appear to be some clinical differences in the presentation of subjects who test positive for CDI by EIA/GDH compared with those who test positive only by GDH/NAA. These differences do not appear to affect length of stay or mortality. Disclosures P. P. Cook, Gilead: Grant Investigator, Grant recipient; Merck: Grant Investigator, Grant recipient; Pfizer: Grant Investigator and Shareholder, Grant recipient

scholarly journals Detection of Clostridium difficile in Feces of Asymptomatic Patients Admitted to the Hospital

2016 ◽  
Vol 55 (2) ◽  
pp. 403-411 ◽  
Author(s):  
Elisabeth M. Terveer ◽  
Monique J. T. Crobach ◽  
Ingrid M. J. G. Sanders ◽  
Margreet C. Vos ◽  
Cees M. Verduin ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Predictive Value ◽  
Health Care Facilities ◽  
Nucleic Acid Amplification ◽  
Content Type ◽  
Asymptomatic Patients ◽  
Toxigenic Culture ◽  
Stool Samples ◽  
Sensitivity Specificity ◽  
Low Prevalence

ABSTRACTRecent evidence shows that patients asymptomatically colonized withClostridium difficilemay contribute to the transmission ofC. difficilein health care facilities. Additionally, these patients may have a higher risk of developingC. difficileinfection. The aim of this study was to compare a commercially available PCR directed to both toxin A and B (artusC. difficileQS-RGQ kit CE; Qiagen), an enzyme-linked fluorescent assay to glutamate dehydrogenase (GDH ELFA) (Vidas, bioMérieux), and an in-house-developed PCR totcdB, with (toxigenic) culture ofC. difficileas the gold standard to detect asymptomatic colonization. Test performances were evaluated in a collection of 765 stool samples obtained from asymptomatic patients at admission to the hospital. TheC. difficileprevalence in this collection was 5.1%, and 3.1% contained toxigenicC. difficile. Compared toC. difficileculture, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of theC. difficileGDH ELFA were 87.2%, 91.2%, 34.7%, and 99.3%, respectively. Compared with results of toxigenic culture, the sensitivity, specificity, PPV, and NPV of the commercially available PCR and the in-house PCR were 95.8%, 93.4%, 31.9%, 99.9%, and 87.5%, 98.8%, 70%, and 99.6%, respectively. We conclude that in a low-prevalence setting of asymptomatically colonized patients, both GDH ELFA and a nucleic acid amplification test can be applied as a first screening test, as they both display a high NPV. However, the low PPV of the tests hinders the use of these assays as stand-alone tests.

scholarly journals 2359. Prospective Feasibility Study for Novel Ultrasensitive Multiplexed Immunoassay for Clostridiodes difficile Toxins A and B

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S812-S813
Author(s):  
Lauren Watson ◽  
Michele L Zimbric ◽  
Catherine Shaughnessy ◽  
Shraddha Kale ◽  
Jeff Debad ◽  
...  
Keyword(s):  
Diagnostic Tests ◽  
Standard Of Care ◽  
Positive Sample ◽  
Nucleic Acid Amplification ◽  
Serum Samples ◽  
Toxin A ◽  
Toxin B ◽  
Diagnostic Assays ◽  
Stool Samples ◽  
Multiplexed Immunoassay

Abstract Background The diagnosis of Clostridiodes difficile infection is challenging. A wide array of diagnostic tests are used in practice; however, each available test has important limitations. We examined the feasibility and analytical performance of a novel ultrasensitive multiplexed immunoassay designed by Meso Scale Diagnostics (MSD) compared with five current diagnostic assays for detection of C. difficile toxin A and B. Methods Stool, serum and urine samples from 44 admitted inpatients were collected within 72 hours of a standard of care nucleic acid amplification test (NAAT) result (23 positive, 21 negative). These specimens underwent five standard diagnostic assays: enzyme immunoassay for toxins A and B (EIA), cytotoxin cell assay, bacterial culture isolation, and two different NAATs to determine presence of viable C. difficile cells, toxins, and toxin-encoding genes (Table 1). The concentration (fg/mL) of toxin A and toxin B in all stool samples was then quantified using MSD’s multiplexed immunoassay (Table 1). Results At least one of the five standard diagnostic tests for C. difficile was positive in 16 of the 23 clinically positive patients. The MSD multiplex immunoassay detected toxin A and/or toxin B in 15 of these 16 samples and quantified low levels of toxin A in one clinically positive sample that was negative for all other tests. In contrast, only 2 of the 16 positive samples were positive by EIA, demonstrating the benefits of the ultrasensitive assay over standard immunoassay methods. All clinically negative specimens were negative in all tests. Toxin detection in urine and serum samples was negligible. In stool samples, the MSD test had an estimated sensitivity of 93% (95% CI: 70–99%) and specificity of 93% (95% CI: 78–98%) compared with the clinically used NAAT. Conclusion The MSD multiplex toxin assay is a feasible test to move forward for further evaluation. Ultimately, future studies should examine the performance of this test compared with standard of care in a prospective randomized trial assessing clinical outcomes. Disclosures All authors: No reported disclosures.

scholarly journals Effectiveness of a Two-Step Testing Algorithm for Reliable and Cost-Effective Detection of Clostridium difficile Infection in a Tertiary Care Hospital in Saudi Arabia

2019 ◽  
Vol 7 (1) ◽  
pp. 6
Author(s):  
Mohammed Qutub ◽  
Prasanth Govindan ◽  
Anupama Vattappillil
Keyword(s):  
Clostridium Difficile ◽  
Clostridium Difficile Infection ◽  
Tertiary Care ◽  
Care Hospital ◽  
Predictive Values ◽  
Stool Samples ◽  
Step Algorithm ◽  
Testing Algorithm ◽  
Sensitivity Specificity ◽  
Pcr Test

The aim of this study was to evaluate the effectiveness of a two-step algorithm for the detection of Clostridium difficile infection. Setting and Design: A two-step testing algorithm was evaluated for testing stool samples from patients suspected of Clostridium difficile infection (CDI). A total of 103 stool specimens were tested using the C. diff Quik Chek Complete enzyme immunoassay (EIA) test and the Xpert C. difficile PCR test. A two-step algorithm was implemented, and data from 3518 patient samples tested during a two-year period after implementation were analyzed to evaluate the effectiveness. The sensitivity, specificity, and positive and negative predictive values (PPV, NPV) of the Quik Chek Complete EIA test were calculated using the Xpert C. difficile PCR test as a reference method. The sensitivity, specificity, PPV, and NPV of the Quik Chek Complete EIA test for C. difficile toxin were 46.7%, 100%, 100%, and 91%, respectively. The two-step algorithm, which combined the Quik Chek Complete EIA with Xpert C. difficile PCR, improved the sensitivity and also provided rapid detection. When algorithm-based testing was performed daily, there was a 66% reduction in turnaround time compared to batch testing using a lengthy ELISA procedure. Postimplementation data analysis showed that almost 89% of the samples could be reported immediately by initial screening with Quik Chek Complete EIA. Only 11% of the samples gave discrepant results and required PCR confirmation. According to our results, the two-step algorithm is an effective tool for the rapid and reliable detection of toxigenic C. difficile from stool samples.

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