scholarly journals The predictive value of quantitative nucleic acid amplification detection ofClostridium difficiletoxin gene for faecal sample toxin status and patient outcome

2018 ◽  
Author(s):  
Kerrie A Davies ◽  
Tim Planche ◽  
Mark H Wilcox
Keyword(s):  
Nucleic Acid ◽  
Predictive Value ◽  
Severe Infection ◽  
Laboratory Diagnosis ◽  
Nucleic Acid Amplification ◽  
Toxin Gene ◽  
Diagnostic Study ◽  
Increased Risk ◽  
Risk Patients ◽  
Using Data

AbstractBackgroundLaboratory diagnosis ofClostridium difficileinfection (CDI) remains unsettled, despite updated guidelines. We investigated the potential utility of quantitative data from a nucleic acid amplification test (NAAT) forC. difficiletoxin gene (tg) for patient management.MethodsUsing data from the largest everC. difficilediagnostic study (8853 diarrhoeal samples from 7335 patients), we determined the predicative value of C. difficile tgNAAT (Cepheid Xpert C.diff) low cycle threshold (CT) value for patient toxin positive status, CDI severity, mortality and CDI recurrence. Reference methods for CDI diagnosis were cytotoxicity assay (CTA) and cytotoxigenic culture (CTC).ResultsOf 1281 tgNAAT positive faecal samples, 713 and 917 were CTA and CTC positive, respectively. The median tgNAAT CT for patients who died was 25.5 vs 27.5 for survivors (p = 0.021); for toxin-positivity was 24.9 vs 31.6 for toxin-negative samples (p<0.001) and for patients with a recurrence episode was 25.6 vs 27.3 for those who did not have a recurrent episode (p = 0.111). Following optimal cut-off determination, low CT was defined as ≤25 and was significantly associated with a toxin-positive result (P<0.001, positive predictive value 83.9%), presence of PCR-ribotype 027 (P=0.025), and mortality (P=0.032). Recurrence was not associated with low CT (p 0.111).ConclusionsLow tgNAAT CT could indicate CTA positive patients, have more severe infection, increased risk of mortality and possibly recurrence. Although, the limited specificity of tgNAAT means it cannot be used as a standalone test, it could augment a more timely diagnosis, and optimise management of these at-risk patients.

scholarly journals Prospective study to find out the role of gastric aspirate examination by Ziehl-Neelsen staining (ZN staining) and cartridge based nucleic acid amplification test (CB-NAAT) as a diagnostic method in childhood tuberculosis

2018 ◽  
Vol 5 (4) ◽  
pp. 1609
Author(s):  
Akansha Arora ◽  
Anil Jain ◽  
B. S. Karnawat ◽  
Rakesh Kumawat
Keyword(s):  
Nucleic Acid ◽  
Predictive Value ◽  
Nucleic Acid Amplification Test ◽  
Nucleic Acid Amplification ◽  
Mantoux Test ◽  
P Value ◽  
Specific Method ◽  
Gastric Aspirate ◽  
Tuberculosis In Children

Background: Tuberculosis in children has been relatively neglected mainly because clinical diagnosis has low specificity, radiological interpretation is subject to inter-observer variability and the tuberculin skin test is a marker of exposure, not disease. The recent introduction of Cartridge based nucleic acid amplification test has significantly transformed the diagnostics of tuberculosis in adults but its application for Paediatric Tuberculosis is under evaluation. Therefore, authors conducted a study on role of gastric aspirate examination by ZN stain and Cartridge based nucleic acid amplification test in the diagnosis of childhood Tuberculosis.Methods: Authors did a prospective hospital-based study from Nov 2016 to Nov 2017 consisting of 100 randomly selected patients suspected of tuberculosis who had their gastric aspirate tested for CBNAAT and ZN stain for acid fast bacilli (AFB) along with Mantoux test and other routine investigations. Chi square test was used.Results: Culture positive tuberculosis was found in 21 out of 100 children. The sensitivity, specificity, positive predictive value and negative predictive value for CBNAAT were 76.1%, 98.7%, 94.1% and 93.9% and for ZN stain were 47.6%, 98.7%, 90.9% and 87.6% respectively. Positive history of contact (p value 0.0217), reactive Mantoux test (p value < 0.001) and low socioeconomic status were independently associated with a positive CBNAAT result.Conclusions: Analysis of gastric aspirate samples with CBNAAT is a sensitive and specific method for rapid diagnosis of pulmonary tuberculosis in children who cannot produce sputum. Compared with microscopy, CBNAAT offers better sensitivity and its scale up will improve access to tuberculosis diagnostics in children.

scholarly journals Low Positive Predictive Value of a Nucleic Acid Amplification Test for NongenitalNeisseria gonorrhoeaeInfection in Homosexual Men

2008 ◽  
Vol 47 (2) ◽  
pp. e25-e27 ◽  
Author(s):  
Leon P. McNally ◽  
David J. Templeton ◽  
Fengyi Jin ◽  
Andrew E. Grulich ◽  
Basil Donovan ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Positive Predictive Value ◽  
Predictive Value ◽  
Nucleic Acid Amplification Test ◽  
Nucleic Acid Amplification ◽  
Homosexual Men

Role of Covid Antigen in the Diagnosis of Covid Positive in Obstetric Patients

2021 ◽  
Vol 15 (10) ◽  
pp. 3356-3358
Author(s):  
Ambreen Fatima ◽  
Nidda Yaseen ◽  
Amna Fareed ◽  
Kashif Ali Samin ◽  
Shumaela Kanwal ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Early Detection ◽  
Negative Predictive Value ◽  
Predictive Value ◽  
False Negative ◽  
Nucleic Acid Amplification ◽  
Antigen Test ◽  
Rt Pcr ◽  
Cross Sectional ◽  
Specificity And Sensitivity

Background and Aim: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapid emergence postured significant challenges on the health system in recent years. The early detection of cases is thought to be critical in preventing this pandemic by coronavirus disease (COVID-19), especially important in the obstetrical population due to theirs numerous interactions with another parturient when hospitalized for delivery. Therefore, the present study aimed to assess the COVID antigen test performance in COVID-positive obstetrics patients. Materials and Methods: This cross-sectional study was conducted on 1296 Covid-19 asymptomatic women admitted to the Obstetrics and Gynaecology Department of Muhammad Teaching Hospital & Medical College, Peshawar and Fauji Foundation Hospital, Rawalpindi for the duration of six months from February 2021 to July 2021. Antigen-based test rapid diagnostic test (RDT) was used for screening out COVID-19 positive obstetrics patients or women through nasopharyngeal swabs. Women with negative rapid antigen test results were confirmed with RT-polymers chain reaction test of nucleic acid amplification tests (NAAT). Ethical approval and informed consent were taken from the hospital ethical committee and each individual respectively. All the known positive COVID-19 patients during admission were excluded. SPSS version 24 was used for data analysis. Results: The overall prevalence of rapid antigen-positive tested patients was 13.2% (171/1296). The prevalence of positive tested women through rapid antigen test, Nucleic Acid Amplification Test (NAAT), and RT-PCR were 27 (2.1%), 51 (3.9%), and 93 (7.2%) respectively. Of the total 1296 rapid antigen tests, 27 were positive, and the false-negative confirmed positive by NAAT was 144.Thus the sensitivity of the rapid antigen test was 15.8% and the negative predictive value was 93.7%. Of the total 298 Nucleic Acid Amplification Tested had sensitivity and negative predictive value of 89.6% and 99.06% respectively. RT-PCR was carried out on 972 patients, positive diagnosed cases were 36 while 15 were initially negative and were positive with the test was repeated. The sensitivity and negative predictive value was 71.45% and 95.8% respectively. Conclusion: Our study found that Ag-RDT plays a significant role in SARS-CoV-2 early detection in infected individuals, with high specificity and sensitivity to disease infectious stage, whether symptomatic or asymptomatic, and can be used as a decision supported tool. Early detection of COVID-19 status in women admitted for delivery could benefit neonatal protection care. Keywords: Covid-19; Rapid antigen test; RT-PCR test

Laboratory Diagnosis of Zika Virus Infection

2016 ◽  
Vol 141 (1) ◽  
pp. 60-67 ◽  
Author(s):  
Marie Louise Landry ◽  
Kirsten St. George
Keyword(s):  
Public Health ◽  
Nucleic Acid ◽  
Virus Infection ◽  
Zika Virus ◽  
Laboratory Diagnosis ◽  
Government Support ◽  
Nucleic Acid Amplification ◽  
Diagnostic Tools ◽  
Nucleic Acid Amplification Tests ◽  
Zika Virus Infection

Context.—The rapid and accurate diagnosis of Zika virus infection is an international priority. Objective.—To review current recommendations, methods, limitations, and priorities for Zika virus testing. Data Sources.—Sources include published literature, public health recommendations, laboratory procedures, and testing experience. Conclusions.—Until recently, the laboratory diagnosis of Zika infection was confined to public health or research laboratories that prepared their own reagents, and test capacity has been limited. Furthermore, Zika cross-reacts serologically with other flaviviruses, such as dengue, West Nile, and yellow fever. Current or past infection, or even vaccination with another flavivirus, will often cause false-positive or uninterpretable Zika serology results. Detection of viral RNA during acute infection using nucleic acid amplification tests provides more specific results, and a number of commercial nucleic acid amplification tests have received emergency use authorization. In addition to serum, testing of whole blood and urine is recommended because of the higher vial loads and longer duration of shedding. However, nucleic acid amplification testing has limited utility because many patients are asymptomatic or present for testing after the brief period of Zika shedding has passed. Thus, the greatest need and most difficult challenge is development of accurate antibody tests for the diagnosis of recent Zika infection. Research is urgently needed to identify Zika virus epitopes that do not cross-react with other flavivirus antigens. New information is emerging at a rapid pace and, with ongoing public-private and international collaborations and government support, it is hoped that rapid progress will be made in developing robust and widely applicable diagnostic tools.

scholarly journals Diagnosis of pulmonary tuberculosis with cartridge based nucleic acid amplification test and light emitting diode fluorescent microscopy: a comparative study

2019 ◽  
Vol 6 (5) ◽  
pp. 1580 ◽  
Author(s):  
Pratik Kumar ◽  
Puneet Bhardwaj
Keyword(s):  
Nucleic Acid ◽  
Pulmonary Tuberculosis ◽  
Negative Predictive Value ◽  
Predictive Value ◽  
Light Emitting Diode ◽  
Fluorescent Microscopy ◽  
Nucleic Acid Amplification Test ◽  
Nucleic Acid Amplification ◽  
Smear Microscopy ◽  
Light Emitting

Background: Due to low sensitivity and inability to detect drug resistance, smear microscopy limits its impact on TB control. Culture methods and drug susceptibility testing is complex, time consuming, and takes around 6-8 weeks. A new diagnostic test, cartridge based nucleic acid amplification test (CBNAAT) was developed based on real-time polymerase chain reaction (RT PCR). Objective of this study to compare the results of CBNAAT for diagnosis of pulmonary tuberculosis with LED fluorescent microscopy and sputum culture.Methods: A cross-sectional study was conducted in the department of Chest and TB, CIMS, Bilaspur. Each Sputum sample of presumptive TB patients were tested with CBNAAT, sputum smear  microscopy by light emitting diode (LED) fluorescent microscopy (FM) and solid and liquid culture for diagnosis of Tuberculosis. Results of CBNAAT, Fluorescent Microscopy and Culture for detection of Mycobacterium Tuberculosis were compared.Results: The sensitivity and specificity for CBNAAT were 97% and 100% respectively; while that for Fluorescent microscopy were 70% and 100% respectively. The positive and negative predictive value for CBNAAT was 100% and 96% respectively. The positive and negative predictive value for Fluorescent microscopy was 100% and 73% respectively.Conclusion: CBNAAT is having high sensitivity and specificity for diagnosis of pulmonary tuberculosis. It should be routinely used under national health programme to detect a tuberculosis case efficiently.

scholarly journals A systematic review and meta-analysis of the sensitivity of antibody tests for the laboratory confirmation of COVID-19

2021 ◽  
Author(s):  
Nigel A Makoah ◽  
Thomas Tipih ◽  
Matefo M Litabe ◽  
Mareza Brink ◽  
Joseph B Sempa ◽  
...  
Keyword(s):  
Systematic Review ◽  
Nucleic Acid ◽  
Symptom Onset ◽  
Meta Analysis ◽  
Nucleic Acid Amplification ◽  
Serological Tests ◽  
Nucleic Acid Amplification Tests ◽  
Laboratory Confirmation ◽  
Using Data ◽  
Low Sensitivity

Aim: The aim of this study was to investigate the utility of serological tests for the diagnosis of COVID-19 during the first week of symptom onset in patients confirmed with the real-time RT-PCR. Materials & methods: A systematic review and meta-analysis of 58 publications were performed using data obtained from Academic Search Ultimate, Africa-wide, Scopus, Web of Science and MEDLINE. Results: We found that the highest pooled sensitivities were obtained with ELISA IgM-IgG and chemiluminescence immunoassay IgM tests. Conclusion: Serological tests have low sensitivity within the first week of symptom onset and cannot replace nucleic acid amplification tests. However, serological assays can be used to support nucleic acid amplification tests.

scholarly journals Mycobacteriosis and Tuberculosis: Laboratory Diagnosis

2018 ◽  
Vol 12 (1) ◽  
pp. 41-58 ◽  
Author(s):  
Davood Azadi ◽  
Tahereh Motallebirad ◽  
Kazem Ghaffari ◽  
Hasan Shojaei
Keyword(s):  
Nucleic Acid ◽  
Case Reports ◽  
Diagnostic Algorithm ◽  
Laboratory Diagnosis ◽  
Etiologic Agent ◽  
Control Measures ◽  
Nucleic Acid Amplification ◽  
Nucleic Acid Hybridization ◽  
Original Research ◽  
Mycobacterial Infections

Background:Tuberculosis is one of the most important infectious diseases that has claimed its victims throughout much of known human history. With Koch's discovery of the tubercle bacillus as the etiologic agent of the disease, his sanitary and hygienic measures, which were based on his discovery and the development of a vaccine against tuberculosis by Albert Calmette and Camille Guérin in 1921, an attenuatedMycobacterium bovisstrain, bacilli Calmette-Guérin (BCG), and the discovery of the first antibiotic against tuberculosis, streptomycin by Selman Waksman in 1943, soon led to the opinion that appropriate control measures had become available for tuberculosis and it had been assumed that the disease could ultimately be eradicated.The emergence of resistant strains of this bacteria and widespread distribution of the disease in the world, and the emergence of the AIDS epidemic destroyed any possibility of global control of tuberculosis in the foreseeable future.Objectives:The purpose of this review is to highlight the current scientific literature on mycobacterial infections and provide an overview on the laboratory diagnosis of tuberculosis and non-tuberculosis infections based on conventional phenotypic and modern molecular assays.Method:In this study, a number of 65 papers comprising 20 reviews, 9 case reports, and 36 original research in association with mycobacteriosis and the laboratory diagnosis of mycobacterial infections, were reviewed.Results:Based on our analysis on the published documents methods applied for the laboratory diagnosis of tuberculosis are continually assessed and developed in order to achieve more rapid, less expensive, and accurate results. Acid-fast staining and culture for mycobacteria remain at the core of any diagnostic algorithm with the sensitivity of 20-70% and specificity of 95-98% for AFB microscopy and the sensitivity of 95% and the specificity of 98% for culture based diagnosis. Following growth in culture, molecular tests such as nucleic acid hybridization probes and DNA sequencing may be used for definitive species identification. Nucleic acid amplification methods provide the means for direct detection ofMycobacterium tuberculosisin respiratory specimens without the prerequisite to isolate or culture the organism, leading to more rapid diagnosis and better patient care.Conclusion:As the researchers in a developing country, we strongly believe that despite significant advances in laboratory capacity, in many countries reliable confirmation of suspected mycobacterial diseases is hindered by a lack of knowledge on proper standardized methods, sufficient funds, suitably trained staff and laboratory supplies.

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