scholarly journals Impact of ribotype on Clostridioides difficile diagnostics

2019 ◽  
Vol 39 (5) ◽  
pp. 847-853 ◽  
Author(s):  
Kristina Rizzardi ◽  
Thomas Åkerlund ◽  
Torbjörn Norén ◽  
Andreas Matussek
Keyword(s):  
Diagnostic Tests ◽  
Diagnostic Performance ◽  
Diagnostic Testing ◽  
Neutralization Assay ◽  
Diagnostic Methods ◽  
Nucleic Acid Amplification ◽  
Predictive Values ◽  
Fecal Samples ◽  
Ribotype 027 ◽  
Clostridioides Difficile

AbstractThis study investigates the performance of diagnostic methods for detection of Clostridioides difficile infection in Sweden, including impact of PCR ribotype on diagnostic performance. Between 2011 and 2016, a total of 17,878 stool samples from 26 laboratories were tested by either well-type enzyme immunoassays (EIAs), membrane bound EIAs, cell cytotoxicity neutralization assay (CTA), or nucleic acid amplification tests (NAATs) and subsequently cultured for C. difficile. Roughly half of the samples (9454/17878) were subjected to diagnostic testing both on the fecal sample and on the 1323 isolated C. difficile strains. All C. difficile isolates were typed by PCR ribotyping, and the isolates were classified as toxigenic or non-toxigenic based on the empirical knowledge of the association between toxin-positivity and ribotype. The overall sensitivity, specificity, and positive and negative predictive values were highest for NAATs and membrane EIAs. Ribotype-specific sensitivity varied greatly between methods and ribotypes. All methods had 100% sensitivity against ribotype 027 and 013. For other types, the sensitivity ranged from 33 to 85% in fecal samples and from 78 to 100% on isolates. For the most prevalent ribotypes (014, 020, and 001), the sensitivity varied between 38 and 100% in the fecal samples, with the lowest sensitivity observed for well-type EIAs and CTA. The large variation in diagnostic sensitivity implies that type distribution significantly affects the outcome when evaluating diagnostic performance. Furthermore, performing comparative studies of diagnostic tests in settings with high prevalence of ribotype 027 will overestimate the general performance of diagnostic tests.

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 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 Evaluation of Malaria Diagnostic Methods as a Key for Successful Control and Elimination Programs

2020 ◽  
Vol 5 (2) ◽  
pp. 102
Author(s):  
Afoma Mbanefo ◽  
Nirbhay Kumar
Keyword(s):  
Nucleic Acid ◽  
Diagnostic Tests ◽  
False Negative ◽  
Protein Detection ◽  
Diagnostic Methods ◽  
Nucleic Acid Amplification ◽  
World Health ◽  
Resource Limited ◽  
Successful Control ◽  
Polymerase Chain

Malaria is one of the leading causes of death worldwide. According to the World Health Organization’s (WHO’s) world malaria report for 2018, there were 228 million cases and 405,000 deaths worldwide. This paper reviews and highlights the importance of accurate, sensitive and affordable diagnostic methods in the fight against malaria. The PubMed online database was used to search for publications that examined the different diagnostic tests for malaria. Currently used diagnostic methods include microscopy, rapid diagnostic tests (RDT), and polymerase chain reaction (PCR). Upcoming methods were identified as loop-mediated isothermal amplification (LAMP), nucleic acid sequence-based amplification (NASBA), isothermal thermophilic helicase-dependent amplification (tHDA), saliva-based test for nucleic-acid amplification, saliva-based test for Plasmodium protein detection, urine malaria test (UMT), and transdermal hemozoin detection. RDT, despite its increasing false negative, is still the most feasible diagnostic test because it is easy to use, fast, and does not need expensive equipment. Noninvasive tests that do not require a blood sample, but use saliva or urine, are some of the recent tests under development that have the potential to aid malaria control and elimination. Emerging resistance to anti-malaria drugs and to insecticides used against vectors continues to thwart progress in controlling malaria. Therefore, future innovation will be required to enable the application of more sensitive and affordable methods in resource-limited settings.

scholarly journals Diagnostics for filovirus detection: impact of recent outbreaks on the diagnostic landscape

2019 ◽  
Vol 4 (Suppl 2) ◽  
pp. e001112 ◽  
Author(s):  
Devy M Emperador ◽  
Laura T Mazzola ◽  
Betsy Wonderly Trainor ◽  
Arlene Chua ◽  
Cassandra Kelly-Cirino
Keyword(s):  
Diagnostic Tests ◽  
Point Of Care ◽  
Rapid Development ◽  
Diagnostic Testing ◽  
Central Africa ◽  
Elisa Test ◽  
Marburg Virus ◽  
Nucleic Acid Amplification ◽  
Poor Access ◽  
Product Profile

Ebolaviruses and Marburg virus (MARV) both belong to the family Filoviridae and cause severe haemorrhagic fever in humans. Due to high mortality rates and potential for spread from rural to urban regions, they are listed on the WHO R&D blueprint of high-priority pathogens. Recent ebolavirus outbreaks in Western and Central Africa have highlighted the importance of diagnostic testing in epidemic preparedness for these pathogens and led to the rapid development of a number of commercially available benchtop and point-of-care nucleic acid amplification tests as well as serological assays and rapid diagnostic tests. Despite these advancements, challenges still remain. While products approved under emergency use licenses during outbreak periods may continue to be used post-outbreak, a lack of clarity and incentive surrounding the regulatory approval pathway during non-outbreak periods has deterred many manufacturers from seeking full approvals. Waning of funding and poor access to samples after the 2014–2016 outbreak also contributed to cessation of development once the outbreak was declared over. There is a need for tests with improved sensitivity and specificity, and assays that can use alternative sample types could reduce the need for invasive procedures and expensive equipment, making testing in field conditions more feasible. For MARV, availability of diagnostic tests is still limited, restricted to a single ELISA test and assay panels designed to differentiate between multiple pathogens. It may be helpful to extend the target product profile for ebolavirus diagnostics to include MARV, as the viruses have many overlapping characteristics.

scholarly journals Reliability of Cobas Amplicor PCR test in detection of Mycobacterium tuberculosis in respiratory and nonorespiratory specimens

2009 ◽  
Vol 66 (12) ◽  
pp. 992-997
Author(s):  
Zorica Lepsanovic ◽  
Dejana Savic ◽  
Branka Tomanovic
Keyword(s):  
Mycobacterium Tuberculosis ◽  
High Sensitivity ◽  
High Specificity ◽  
Diagnostic Methods ◽  
Nucleic Acid Amplification ◽  
Culture Methods ◽  
Predictive Values ◽  
Polymerase Chain ◽  
Low Sensitivity ◽  
Sensitivity Specificity

Background/Aim. Traditional methods for detection of mycobacteria, such as microscopic examination for the presence of acid-fast bacilli and isolation of the organism by culture, have either a low sensitivity and/or specificity, or take weeks before a definite result is available. Molecular methods, especially those based on nucleic acid amplification, are rapid diagnostic methods which combine high sensitivity and high specificity. The aim of this study was to determine the usefulness of the Cobas Amplicor Mycobacterium tuberculosis polymerase chain reaction (CAPCR) assay in detecting the tuberculosis cause in respiratory and nonrespiratory specimens (compared to culture). Methods. Specimens were decontaminated by the N-acetyl-L-cystein- NaOH method. A 500 ?L aliquot of the processed specimen were used for inoculation of L?wenstein-Jensen (L-J) slants, a drop for acid-fast staining, and 100 ?L for PCR. The Cobas Amplicor PCR was performed according to the manufacturer's instructions. Results. A total of 110 respiratory and 355 nonrespiratory specimens were investigated. After resolving discrepancies by reviewing medical history, overall sensitivity, specificity, and positive and negative predictive values for CA-PCR assay compared to culture, were 83%, 100%, 100%, and 96.8%, respectively. In comparison, they were 50%, 99.7%, 87.5%, and 98%, respectively, for the nonrespiratory specimens. The inhibition rate was 2.8% for respiratory, and 7.6% for nonrespiratory specimens. Conclusion. CA-PCR is a reliable assay that enables specialists to start treatment promptly on a positive test result. Lower value for specificity in a group of nonrespiratory specimens is a consequence of an extremely small number of mycobacteria in some of them.

scholarly journals Comparison of Diagnostic Tests for Detection of Bovine Rotavirus a in Calf Feces

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Shama Ranjan Barua ◽  
Shariful Islam ◽  
А.М.А.М. Zonaed Siddiki ◽  
Md Masuduzzaman ◽  
Mohammad Alamgir Hossain ◽  
...  
Keyword(s):  
Diagnostic Tests ◽  
Rapid Test ◽  
Diagnostic Methods ◽  
Diagnostic Tools ◽  
Rt Pcr ◽  
Fecal Samples ◽  
Rotavirus A ◽  
Bovine Rotavirus ◽  
Test Elisa ◽  
Calf Mortality

AbstractBovine rotavirus A (BRVA) is a frequent causative agent of diarrhea in neonatal calves. Accurate and rapid diagnosis is crucial to prevent calf mortality from BRVA induced diarrhea. Currently, variety of diagnostic methods are being used to detect BRVA from calves’ feces: antibody-based rapid test and ELISA, and molecular-based RT-PCR and RT-qPCR. The aim of the study was to evaluate the accuracy (sensitivity and specificity) of the rapid test (Immunochromatography), ELISA, and RT-PCR assays, using RT-qPCR as the gold standard, in detection of BRVA in diarrheic calves’ fecal samples. One hundred (n=100) clinically diarrheic fecal samples were tested with four different diagnostic tools. The percent of samples positive by rapid test, ELISA, RT-PCR and RT-qPCR was 10%, 16%, 17%, and 33%, respectively. The agreement between different assays was 75% to 99%. The highest agreement was observed between ELISA and RT-PCR assay (99%). The lowest agreement was recorded (75%) between rapid test and RT-qPCR. The sensitivity of the rapid test, ELISA, and RT-PCR were 30%, 49%, and 52%, respectively when compared to the reference test (RT-qPCR), whereas specificity was 100% for all assays. In conclusion, none of the frequently used diagnostic tests showed a satisfactory level of sensitivity to identify BRVA in calves’ feces. Therefore, the use of a more sensitive rapid test should be used to identify infected calves in field conditions in order to prevent calf mortality from rotaviral diarrhea.

scholarly journals Lipoarabinomannan as a Point-of-Care Assay for Diagnosis of Tuberculosis: How Far Are We to Use It?

2021 ◽  
Vol 12 ◽  
Author(s):  
Julio Flores ◽  
Juan Carlos Cancino ◽  
Leslie Chavez-Galan
Keyword(s):  
Diagnostic Tests ◽  
Point Of Care ◽  
Diagnostic Testing ◽  
Public Health Problem ◽  
Etiologic Agent ◽  
Diagnostic Methods ◽  
World Health ◽  
Soluble Form ◽  
Health Organization ◽  
Low Sensitivity

Tuberculosis (TB) is still a severe public health problem; the current diagnostic tests have limitations that delay treatment onset. Lipoarabinomannan (LAM) is a glycolipid that is a component of the cell wall of the bacillus Mycobacterium tuberculosis, the etiologic agent of TB. This glycolipid is excreted as a soluble form in urine. The World Health Organization has established that the design of new TB diagnostic methods is one of the priorities within the EndTB Strategy. LAM has been suggested as a biomarker to develop diagnostic tests based on its identification in urine, and it is one of the most prominent candidates to develop point-of-care diagnostic test because urine samples can be easily collected. Moreover, LAM can regulate the immune response in the host and can be found in the serum of TB patients, where it probably affects a wide variety of host cell populations, consequently influencing the quality of both innate and adaptive immune responses during TB infection. Here, we revised the evidence that supports that LAM could be used as a tool for the development of new point-of-care tests for TB diagnosis, and we discussed the mechanisms that could contribute to the low sensitivity of diagnostic testing.

scholarly journals 4345 Two-step Algorithm for Clostridioides difficile is Inadequate for Differentiating Infection from Colonization in Children

2020 ◽  
Vol 4 (s1) ◽  
pp. 150-150
Author(s):  
Maribeth R Nicholson ◽  
Jacob M Parnell ◽  
Irtiqa Fazili ◽  
Sarah C. Bloch ◽  
D. Borden Lacy ◽  
...  
Keyword(s):  
Clinical Laboratory ◽  
Clinical Care ◽  
Diagnostic Testing ◽  
Neutralization Assay ◽  
Clostridioides Difficile ◽  
Asymptomatic Children ◽  
Study Population ◽  
Step Algorithm ◽  
New Guidelines ◽  
Testing Algorithm

OBJECTIVES/GOALS: In 2017, new guidelines recommended multi-step algorithms for CDI diagnosis, and clinical centers rapidly implemented changes despite limited pediatric data. We assessed a multi-step algorithm using NAAT followed by EIA for ability to differentiate symptomatic CDI from colonization in children. METHODS/STUDY POPULATION: We prospectively enrolled pediatric patients with cancer, cystic fibrosis, or inflammatory bowel disease who were not being tested or treated for CDI and obtained a stool sample for NAAT. If positive by NAAT (colonized), EIA was performed. Children with symptomatic CDI who tested positive by NAAT via the clinical laboratory were also enrolled and EIA performed on residual stool. A functional cell cytotoxicity neutralization assay (CCNA) was performed in addition. RESULTS/ANTICIPATED RESULTS: Of the 138 asymptomatic children enrolled, 24 (17%) were colonized. An additional 37 children with symptomatic CDI were enrolled. Neither EIA positivity (41% versus 21%, P = 0.11) or CCNA positivity (49% versus 46%, P = 0.84) were significantly different between symptomatic versus colonized children. When both EIA and CCNA were positive, children were more commonly symptomatic than colonized (33% versus 13%, P = 0.04). DISCUSSION/SIGNIFICANCE OF IMPACT: A multi-step testing algorithm with NAAT and EIA failed to differentiate symptomatic CDI from colonization in our pediatric cohort. As multi-step algorithms are moved into clinical care, pediatric providers will need to be aware of the continued limitations in diagnostic testing.

scholarly journals Comparative Evaluation of the Diagnostic Performance Characteristics of a One-Step Urine Malaria Test (UMT) against Rapid Diagnostic Tests (RDT) in Febrile Patients from Fako Division, Cameroon

2020 ◽  
Author(s):  
Nforbugwe Achu Che Awah ◽  
Rengerline Bihnwi Nchotu ◽  
Agnes Djema Bongah ◽  
Jules Clement Nguedia Assob
Keyword(s):  
Diagnostic Tests ◽  
Diagnostic Performance ◽  
Blood Smear ◽  
Limit Of Detection ◽  
Kidney Diseases ◽  
Rapid Diagnostic Tests ◽  
Diagnostic Methods ◽  
Performance Characteristics ◽  
Smear Microscopy ◽  
Malaria Test

Abstract Background : Presently, all malaria diagnostic methods like: microscopy and Rapid Diagnostic Tests (RDT) are invasive as they depend on blood samples for malaria diagnosis. Hence this study was aimed at comparing the diagnostic performance characteristics of the novel Urine Malaria Test (UMT) to the currently used Blood RDT, and to find out the efficacy of this UMT in detecting low parasitaemia in the study population. Methodology : A cross sectional study involving 200 febrile participants, with no signs and symptoms of rheumatoid arthritis and kidney diseases, no history of hematuria, >15/µl leucocytes and urobilinogens of > 1 mg/dl in their urine, were recruited from the month of April to August 2017 in the Limbe and Buea Regional Hospitals. The main samples requested for analyses were urine and blood. Results : Using the blood smear microscopy as standard, out of the 200 participants, 93 (46.5%) were positive for P . malaria. UMT had a sensitivity and specificity of 82.41% and 83.48 while that of RDT was 84.09% and 83.03 respectively falciparum (CI: 72.80 to 92.05%, Kappa 0.665, p =0.001). The UMT had a lowest limit of detection of 140 parasites/μl which was similar to RDT. The PPV and NPV of UMT and RDT were (81.74% and 85.98%) and (80.04% and 87.28%), respectively. There was a close agreement between the RDT and UMT when compared to microscopy (83.5% and 83.0% respectively). Conclusion : The UMT kit that was evaluated in comparison to the blood based RDT, showed a lot of similarities using the blood smear microscopy as gold standard. Hence, it can be recommended for the prompt and accurate diagnosis of malaria in febrile patients.

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.

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