scholarly journals Association of Cartridge Based Nucleic Acid Amplification Test (CBNAAT) Grading on the Basis of Cycle Threshold Value with Conventional Microbiological Diagnosis in Pediatric Tuberculosis

2021 ◽  
Vol 7 (2) ◽  
pp. 72-77
Author(s):  
Bineeta Kashyap ◽  
Neha Gupta ◽  
Pooja Dewan ◽  
NP Singh ◽  
Ashwani Khanna
Keyword(s):  
Nucleic Acid ◽  
Positive Association ◽  
Threshold Value ◽  
Nucleic Acid Amplification Test ◽  
Nucleic Acid Amplification ◽  
Microbiological Diagnosis ◽  
Significant Positive Association ◽  
Cycle Threshold ◽  
Culture Positivity ◽  
Pediatric Tuberculosis

Background: Microbiological confirmation of tuberculosis disease in children remains difficult due to paucibacillary disease and inability to obtain optimal samples. Recently introduced Cartridge based nucleic acid amplification test (CBNAAT) has improved microbiological diagnosis in pediatric tuberculosis. Objectives: We aimed to study association of CBNAAT grading based on cycle threshold value with conventional microbiological diagnosis. Methodology: This prospective study was conducted over a period from November 2016 to October 2017 in the Departments of Microbiology and Pediatrics, University College of Medical Sciences and Guru Teg Bahadur Hospital, Delhi. CBNAAT positive pediatric TB cases ≤12 years were recruited and subjected to Ziehl-Neelsen staining for acid fast bacilli (AFB) & culture on Lowenstein Jensen medium. CBNAAT positivity was graded based on cycle threshold value: very low, low, medium and high. Results: Smear and culture positivity was highest (100%) among specimens with high positive CBNAAT result based on CT value. Time to culture positivity was inversely related to CBNAAT grading (p=0.000). Conclusion: CBNAAT grading has significant positive association with smear and culture positivity. Bangladesh Journal of Infectious Diseases 2020;7(2):72-77

scholarly journals A Retrospective Cross-Sectional Study of the Utility of Cartridge-Based Nucleic Acid Amplification Test in Diagnosis of Pulmonary and Extrapulmonary Tuberculosis in People Living with HIV in Second Highest HIV Prevalent State in India

2021 ◽  
Author(s):  
Tade Bagbi ◽  
Ningthoukhongjam Reema ◽  
S. Bhagyabati Devi ◽  
Thangjam Gautam Singh ◽  
Mohammad Jaleel ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Cross Sectional Study ◽  
Nucleic Acid Amplification Test ◽  
Nucleic Acid Amplification ◽  
Rifampicin Resistance ◽  
Sputum Smear ◽  
Smear Microscopy ◽  
Sectional Study ◽  
Cross Sectional ◽  
Smear Negative

Abstract Introduction Tuberculosis (TB) in people living with human immunodeficiency virus (PLHIV) is difficult to diagnose due to fewer organisms in sputum and extrapulmonary samples. Sputum culture takes 4 to 8 weeks for growth of the mycobacteria. Delayed treatment for TB in PLHIV leads to increased mortality. This study evaluated cartridge-based nucleic acid amplification test (CBNAAT) as a diagnostic tool for diagnosis of pulmonary TB (PTB) and extrapulmonary TB (EPTB) in PLHIV in the second most HIV prevalent state in India and for comparing its efficacy between Ziehl–Neelsen (ZN) staining sputum smear–positive and sputum smear–negative TB. Methods This cross-sectional study was conducted in RIMS, Imphal, with 167 PLHIV patients, age 15 years or older, having signs and symptoms of TB. Appropriate samples for sputum microscopy and CBNAAT were sent. Conclusion The overall sensitivity of sputum smear for acid-fast bacillus (AFB) was found to be 30.71% and that of CBNAAT was 38.57%. Sensitivity of CBNAAT for sputum smear–positive and sputum smear–negative TB was 100 and 11.3%, respectively. Sensitivity of ZN smear for AFB of EPTB sample was 48.1% and that of CBNAAT was 59.25%. In both PTB and EPTB, CBNAAT showed an increase in diagnosis of microbiologically confirmed PTB cases by 7.8 and 11.1%, respectively, over and above the cases diagnosed by ZN smear microscopy. Rifampicin resistance was detected in five patients. We conclude that CBNAAT is a rapid test with better sensitivity in diagnosis of PTB and EPTB in PLHIV, compared with ZN smear microscopy. It detects rifampicin resistance for multidrug-resistant TB and helps in early treatment intervention.

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 Dual Reporting of Clostridioides difficile PCR and Predicted Toxin Result Based on PCR Cycle Threshold Reduces Treatment of Toxin-Negative Patients without Increases in Adverse Outcomes

2019 ◽  
Vol 57 (11) ◽  
Author(s):  
Matthew M. Hitchcock ◽  
Marisa Holubar ◽  
Catherine A. Hogan ◽  
Lucy S. Tompkins ◽  
Niaz Banaei
Keyword(s):  
Nucleic Acid ◽  
Chart Review ◽  
Patient Characteristics ◽  
Adverse Outcomes ◽  
Nucleic Acid Amplification ◽  
Content Type ◽  
Cycle Threshold ◽  
Clostridioides Difficile ◽  
All Cause Mortality ◽  
High Negative Predictive Value

ABSTRACT Nucleic acid amplification tests are commonly used to diagnose Clostridioides difficile infection (CDI). Two-step testing with a toxin enzyme immunoassay is recommended to discriminate between infection and colonization but requires additional resources. Prior studies showed that PCR cycle threshold (CT) can predict toxin positivity with high negative predictive value. Starting in October 2016, the predicted toxin result (CT-toxin) based on a validated cutoff was routinely reported at our facility. To evaluate the clinical efficacy of this reporting, all adult patients with positive GeneXpert PCR results from October 2016 through October 2017 underwent a chart review to measure the recurrence of or conversion to a CT-toxin+ result and 30-day all-cause mortality. There were 482 positive PCR tests in 430 unique patients, 282 CT-toxin+ and 200 CT-toxin−. Patient characteristics were similar at testing, though CT-toxin+ patients had higher white blood cell (WBC) counts (12.5 × 103 versus 9.3 × 103 cells/μl; P = 0.001). All cases (n = 21) of fulminant CDI had a CT-toxin+ result. Index CT-toxin+ patients were significantly more likely to have a CT-toxin+ result within 90 days than CT-toxin− patients (17.4% [n = 49] versus 8.0% [n = 16], respectively; P = 0.003). Thirty-day all-cause mortality was higher in CT-toxin− patients (11.1% versus 6.8%; P = 0.1), though no deaths in CT-toxin− patients were directly attributable to CDI. Of the 200 CT-toxin− patients, 51.5% (n = 103) were treated for CDI. The rates of conversion to a CT-toxin+ result (8.8% versus 7.2%; P = 0.8) and all-cause mortality (8.8% versus 13.4%; P = 0.3) were similar between treated and untreated CT-toxin− patients, respectively. CT-based toxin prediction may identify patients at higher risk for CDI-related complications and reduce treatment among CT-toxin− patients.

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