1. The diagnostic impact of implementing a molecular-based algorithm to standard mycobacterial screening at a reference laboratory with an intermediate prevalence for non-respiratory samples
- Author
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Kamel M. Aldosari, Suzan M. Zareah, Khalid S. Alasmari, Shafi F. Alharbi, Ibrahim M. Alduealej, Abdulwahab Z. Binjomah, and Amani Alnimr
- Subjects
0106 biological sciences ,0301 basic medicine ,Routine testing ,QH301-705.5 ,Reference laboratory ,Non-respiratory samples ,01 natural sciences ,Mycobacterium tuberculosis ,03 medical and health sciences ,Medicine ,Biology (General) ,Respiratory samples ,biology ,business.industry ,Gold standard (test) ,biology.organism_classification ,bacterial infections and mycoses ,030104 developmental biology ,Original Article ,General Agricultural and Biological Sciences ,business ,Algorithm ,Rifampicin ,010606 plant biology & botany ,medicine.drug ,Xpert MTB/RIF assay ,NND - Abstract
Rapid, reliable results can be given by molecular, direct detection and identification of the Mycobacterium tuberculosis (MTB/Mtb) complex from clinical samples. The Xpert MTB/RIF assay is an assay that has been availablefor more than a decade for identification of Mycobacterium tuberculosis and resistance to rifampicin. However, there is minimal evidence on its clinical usefulness in paucibacillary, non-respiratory samples. The Xpert MTB/RIF assay clinical utility index, its diagnostic characteristics and the number required to diagnose 2935 non-respiratory specimens submitted for routine mycobacterial work-up in a reference laboratory in an intermediate prevalence setting per specimen form were evaluated. The Xpert MTB/RIF assay showed a variable clinical utility index and number required to diagnose (NND) depending on the type of specimen, which was moderate in tissue biopsies (NND = 1.8) and excellent in pus and urine samples, compared to acid-fast microscopy and culture as a gold standard technique (NND = 1.1 and 1.2). Microscopy, on the other hand, consistently showed a weak to fair index of clinical usefulness in all specimen forms, with in NND of 2.3–12.5. The NND for detecting tuberculous infection in the cerebrospinal fluid by the Xpert MTB/RIF assay was noted to be 1.2, with a moderate clinical utility index of 0.8. The evidence presented indicates that the overall appropriate diagnostic utility of the Xpert MTB/RIF assay is clinically successful in most non-respiratory samples. To check the cost-effectiveness and prognostic effect of integrating this completely automated molecular-based assay into the routine testing algorithm for non-respiratory mycobacterial specimens, further data must be collected.
- Published
- 2021