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Rapid Methods in Cosmetic Microbiology
Published in Philip A. Geis, Cosmetic Microbiology, 2020
Nucleic acid amplification-based rapid technologies utilize a number of gene amplification and detection platforms, including polymerase chain reaction (PCR), transcription-mediated amplification, 16S rRNA typing and gene sequencing. Most of these methods will detect the presence of a target microorganism or generate data that can be used to determine the identification of an isolate, from the genus level down to the sub-species and/or strain level (Table 7.5).
Extrapulmonary Tuberculosis
Published in Lloyd N. Friedman, Martin Dedicoat, Peter D. O. Davies, Clinical Tuberculosis, 2020
M. tuberculosis can be isolated from urine in 80%–90% of patients who have three morning urine specimens obtained for culture.29 In patients with pulmonary TB, urine cultures have been reported to be positive in approximately 5% of cases. In renal TB, urine AFB stains have a sensitivity of approximately 50% and specificity of 97%.207,213 Urine nucleic acid amplification has a sensitivity of 56%–96% and specificity of 98%.29 An intravenous pyelogram may show evidence of destructive changes in the kidney or ureteral abnormalities such as strictures and hydronephrosis. CT often demonstrates renal enlargement with abscess formation (Figure 14.7). Ultrasound guided FNA can identify typical histopathological features in 86%–94% of patients and culture is positive in about 45% of samples.214
Emerging Potential of In Vitro Diagnostic Devices: Applications and Current Status
Published in Debarshi Kar Mahapatra, Sanjay Kumar Bharti, Medicinal Chemistry with Pharmaceutical Product Development, 2019
Swarnali Das Paul, Gunjan Jeswani
Widespread RDTs which are in use today are based on the principle of immunoassay which involves the interaction of a fixed reagent linked to specific types of detector (visible) with a patient sample. The fixed reagent may be either target antigen or antibody. Other technologies like nucleic-acid amplification is very costly due to very advanced technology involved and difficult to apply as a point of care test.
Diagnostic approaches for dengue infection
Published in Expert Review of Molecular Diagnostics, 2023
Gaythri Thergarajan, Shamala Devi Sekaran
The DENV has a single stranded RNA genome coding for three structural proteins and five non-structural proteins (capsid protein, membrane protein, envelope protein, NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5) [10]. The proteins are arranged in the sequence of NH2-C-M-E-NS1-NS2A-NS2B-NS3-NS4-NS4B-NS5-COOH as a single polyprotein precursor consisting nearly 11,000 nucleotides [11,12]. Diagnosis begins with a clinical suspicion which are not unique to dengue and hence limited in its usefulness for early diagnosis. Clinical symptoms have high sensitivities but have poor specificities and hence a confirmatory diagnosis is essential. Currently, markers used include the NS1, IgM and IgG antibodies. Virus isolation is not routinely done except in reference centers and research laboratories. Nucleic acid amplification is not as popular and only utilized in laboratories tracking infections or public health laboratories. Most of them amplify the E regions while some include the pre-M, capsid and/or the NS5 regions. The titers of the IgM and IgG antibodies depend on whether the infection is a primary or a secondary infection. This can only be determined by quantitative or semi-quantitative methods. The main issue with confirmatory assays is the validation of each assay. Hence, early diagnosis remains a challenge, more so the markers to use and the time frame of detection. A combination of clinical markers and laboratory-confirmed assays may serve as predictive markers at different stages of the disease.
Point of care molecular and antigen detection tests for COVID-19: current status and future prospects
Published in Expert Review of Molecular Diagnostics, 2022
William Stokes, Byron M. Berenger, Allison A. Venner, Vincent Deslandes, Julie L. V. Shaw
With any NAAT, contamination is always a concern, though it is minimized by keeping samples in closed devices during and after nucleic acid amplification. Regular cleaning of the area and the testing device should be strictly adhered to. Only the cobas Liat has had documented reports of contamination leading to false-positive results, because of leaky testing cartridges [16]. While the risk of false-positive results may be low, there exists a theoretical contamination risk for users that was highlighted in a recent publication [82]. Using a fluorescent mock sample, the authors were able to demonstrate sample traces on the gloves of users and on the ID NOW instrument surfaces. This may be linked with the manufacturer-suggested sample collection method, which suggests re-insertion of the collection swab back into its wrapper following sampling. This study also identified that, when compared to a POCT RAT, the ID NOW was perceived less favorably by users with no prior laboratory experience in terms of ease of utilization.
Development of amplification system for point-of-care test of nucleic acid
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Shaolei Huang, Jiageng Wu, Haozheng Dai, Runxin Gao, Hongyu Lin, Dongxu Zhang, Shengxiang Ge
NAT can be divided into three main steps which contains extraction, amplification and detection. Usually, the initial DNA concentration of samples is too low to be detected directly. Therefore, nucleic acid amplification is important to increase the nucleic acid exponentially to reach detectable level. In recent years, isothermal amplification techniques represented by LAMP and NASBA have developed rapidly, which have the advantages of high amplification efficiency, high specificity, short reaction time and low requirements for instruments (Yan et al. 2020, Lu et al. 2020), and are now able to be applied in clinical diagnosis. However, isothermal amplification technology still has some shortcomings, firstly, the primer design for isothermal amplification is complex, and the amplification process requires a variety of enzymes (Notomi et al. 2000), and the deployment of biological reagents is also difficult. Secondly, isothermal amplification is currently unable to achieve quantitative detection for clinical applications, the concentration of the virus is not accurate enough for doctors to monitor the effect of treatment and adjust the treatment plan.