scholarly journals Despite excellent test characteristics of the cobas®4800 CT/NG assay, detection of oropharyngeal Chlamydia trachomatis and Neisseria gonorrhoeae remains challenging

2020 ◽  
Author(s):  
J. M. Van Niekerk ◽  
B. M. J. W. van der Veer ◽  
C. J. P. A. Hoebe ◽  
J van de Bovenkamp ◽  
C van Herk ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
Neisseria Gonorrhoeae ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Full Range ◽  
Probability Of Detection ◽  
Nucleic Acid Amplification ◽  
Clinical Samples ◽  
Test Characteristics ◽  
Missed Diagnoses

Objectives : Oropharyngeal Chlamydia trachomatis (CT) and especially Neisseria gonorrhoeae (NG) infections are common but few commercial nucleic acid amplification tests (NAATs) specify extragenital samples as intended use. The test characteristics of the cobas®4800 CT/NG assay are evaluated for oropharyngeal swabs. Methods: The technical validation includes analysis of the specificity, sensitivity, dynamic range, linearity, efficiency and precision. The probability of detection curve combined with historical data enables estimation of potentially missed diagnoses. A clinical evaluation has been performed on a subset of 2798 clinical samples available from routine diagnostics. Results of the cobas®4800 were compared with in-house CT/NG PCR assays. Discrepant samples were tested with resolver assays and these results were considered decisive. Results: No cross-reactivity was seen in the analytical specificity analysis. High linearity (≥0.983 R2), efficiency (89%-99%), and precision (0.1-0.9 Ct-value) were seen for both CT/NG. The limit of detection in oropharyngeal samples was 3.2x102 IFU/mL for CT and 6.7x102 CFU/mL for NG. Estimates on potentially missed diagnoses were up to 7.2% for CT and up to 24.7% for NG. Clinical sensitivity and specificity were evaluated with 25 CT, 86 NG positive and 264 negative samples, resulting in 100% and 99.6% for CT and 100% and 96.7% for NG respectively. Conclusion: The findings in this study demonstrate the utility of the cobas®4800 CT/NG assay for oropharyngeal samples. Despite being a highly accurate test, the range of reported Ct-values especially for NG suggest relatively low oropharyngeal loads. Hence, consistent detection over the full range of oropharyngeal loads could be impaired.

Diagnostic tests for detecting Chlamydia trachomatis and Neisseria gonorrhoeae in rectal and pharyngeal specimens

2021 ◽  
Author(s):  
Paul C. Adamson ◽  
Jeffrey D. Klausner
Keyword(s):  
Chlamydia Trachomatis ◽  
Neisseria Gonorrhoeae ◽  
Bacterial Infections ◽  
Point Of Care ◽  
High Sensitivity ◽  
Population Level ◽  
The United States ◽  
Nucleic Acid Amplification ◽  
Point Of Care Test ◽  
Control And Prevention

Chlamydia trachomatis and Neisseria gonorrhoeae are two of the most often reported bacterial infections in the United States. The rectum and oropharynx are important anatomic sites of infection and can contribute to ongoing transmission. Nucleic acid amplification tests (NAATs) are the mainstays for the detection of C. trachomatis and N. gonorrhoeae infections owing to their high sensitivity and specificity. Several NAATs have been evaluated for testing in rectal and pharyngeal infections. A few assays recently received clearance by the Food and Drug Administration, including one point-of-care test. Those assays can be used for testing in symptomatic individuals, as well as for asymptomatic screening in certain patient populations. Routine screening for C. trachomatis in pharyngeal specimens is not recommended by the Centers for Disease Control and Prevention, though is often performed due to the use of multiplex assays. While expanding the types of settings for screening and using self-collected rectal and pharyngeal specimens can help to increase access and uptake of testing, additional research is needed to determine the potential benefits and costs associated with increased screening for rectal and pharyngeal C. trachomatis and N. gonorrhoeae infections on a population level.

Performance evaluation of cobas HBV real-time PCR assay on Roche cobas 4800 System in comparison with COBAS AmpliPrep/COBAS TaqMan HBV Test

2018 ◽  
Vol 56 (7) ◽  
pp. 1133-1139 ◽  
Author(s):  
Hanah Kim ◽  
Mina Hur ◽  
Eunsin Bae ◽  
Kyung-A Lee ◽  
Woo-In Lee
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Limit Of Detection ◽  
Nucleic Acid Amplification ◽  
Coefficient Of Determination ◽  
Clinical Samples ◽  
Pcr Assay ◽  
Cobas Taqman ◽  
Limit Of Quantitation ◽  
Two Systems

Abstract Background: Hepatitis B virus (HBV) nucleic acid amplification testing (NAAT) is important for the diagnosis and management of HBV infection. We evaluated the analytical performance of the cobas HBV NAAT (Roche Diagnostics GmbH, Mannheim, Germany) on the cobas 4800 System in comparison with COBAS AmpliPrep/COBAS TaqMan HBV Test (CAP/CTM HBV). Methods: Precision was evaluated using three levels of cobas HBV/HCV/HIV-1 Control Kit, and linearity was evaluated across the anticipated measuring range (10.0–1.0×109 IU/mL) at seven levels using clinical samples. Detection capability, including limit of blank (LOB), limit of detection (LOD) and limit of quantitation (LOQ), was verified using the 4th WHO International Standard for HBV DNA for NAT (NIBSC code: 10/266). Correlation between the two systems was compared using 205 clinical samples (102 sera and 103 EDTA plasma). Results: Repeatability and total imprecision (coefficient of variation) ranged from 0.5% to 3.8% and from 0.5% to 3.5%, respectively. Linearity (coefficient of determination, R2) was 0.999. LOB, LOD and LOQ were all acceptable within the observed proportion rate (85%). Correlation was very high between the two systems in both serum and plasma samples (correlation coefficient [r]=0.995). Conclusions: The new cobas HBV real-time PCR assay on the cobas 4800 System showed reliable analytical performances.

scholarly journals Analytical Performances of Human Immunodeficiency Virus Type 1 RNA-Based Amplix® Real-Time PCR Platform for HIV-1 RNA Quantification

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Christian Diamant Mossoro-Kpinde ◽  
Ralph-Sydney Mboumba Bouassa ◽  
Mohammad-Ali Jenabian ◽  
Serge Tonen Wolyec ◽  
Leman Robin ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
Central Africa ◽  
Sub Saharan Africa ◽  
Clinical Samples ◽  
Absolute Bias ◽  
Sub Saharan ◽  
Hiv 1

Objectives. We evaluated the performances of Amplix real-time PCR platform developed by Biosynex (Strasbourg, France), combining automated station extraction (Amplix station 16 Dx) and real-time PCR (Amplix NG), for quantifying plasma HIV-1 RNA by lyophilized HIV-1 RNA-based Amplix reagents targeting gag and LTR, using samples from HIV-1-infected adults from Central African Republic. Results. Amplix real-time PCR assay showed low limit of detection (28 copies/mL), across wide dynamic range (1.4–10 log copies/mL), 100% sensitivity and 99% specificity, high reproducibility, and accuracy with mean bias < 5%. The assay showed excellent correlations and concordance of 95.3% with the reference HIV-1 RNA load assay (Roche), with mean absolute bias of +0.097 log copies/mL by Bland-Altman analysis. The assay was able to detect and quantify the most prevalent HIV-1 subtype strains and the majority of non-B subtypes, CRFs of HIV-1 group M, and HIV-1 groups N and O circulating in Central Africa. The Amplix assay showed 100% sensitivity and 99.6% specificity to diagnose virological failure in clinical samples from antiretroviral drug-experienced patients. Conclusions. The HIV-1 RNA-based Amplix real-time PCR platform constitutes sensitive and reliable system for clinical monitoring of HIV-1 RNA load in HIV-1-infected children and adults, particularly adapted to intermediate laboratory facilities in sub-Saharan Africa.

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