Doctoral Degrees (Molecular Biology and Human Genetics)
Permanent URI for this collection
Browse
Browsing Doctoral Degrees (Molecular Biology and Human Genetics) by Author "Barnard, Marinus"
Now showing 1 - 1 of 1
Results Per Page
Sort Options
- ItemDiagnostic utility of the line probe assay for the detection of drug resistance in Mycobacterium tuberculosis(Stellenbosch : Stellenbosch University, 2013-03) Barnard, Marinus; Warren, Robin Mark; Gey van Pittius, Nicolaas C.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences. Division Molecular Biology and Human GeneticsENGLISH ABSTRACT: The epidemic levels of drug-resistant tuberculosis (DR-TB) in high-burden countries such as South Africa, which is currently ranked as third highest in the world, is the result of a synergistic relationship between the increased transmission of DR strains, poor patient adherence as well as Human-Immunodeficiency Virus (HIV)-coinfection. The impact of these combined factors on the rise of DR-TB led to an urgent need for the development of new diagnostic tools to rapidly detect TB and its associated drug susceptibility profile. The Foundation for Innovative New Diagnostics (FIND) has taken the onus upon them to ensure that laboratory strengthening becomes a reality by having developed, and still developing, new diagnostic assays in order to improve the laboratory turn-around time (TAT), whereby the transmission of DR-TB strains can be stopped. Laboratory strengthening does not solely rely on new diagnostic assays alone, and thus a Quality Management System, discussed in the dissertation, must be in place to ensure that the rapid result is accurate and reliable. The series of studies encompassed in this dissertation includes methodological validations (both technical and operational) of rapid TB diagnostic assays in order to rapidly and accurately diagnose the disease, and thus reducing the diagnostic delay associated with conventional diagnostic platforms. The studies were conducted “in-house” at the National Health Laboratory Service (NHLS) Reference TB laboratory in Green Point, Cape Town, which is a high-volume public health laboratory. The need to rapidly detect resistance to the first line anti-tubercular drugs Isoniazid and Rifampicin was a priority and thus the performance of a commercial line probe assay (LPA), the GenoType®MTBDRplus Ver1.0 LPA, was assessed for use on smear positive direct patient material. The performance characteristics was superior to that of conventional drug susceptibility testing, where the sensitivity and specificity for the detection of multi-drug resistant TB (MDR-TB) was 98.8 and 100%, respectively, with results in 1-2 days. Based on this study, the World Health Organization (WHO) endorsed the use of molecular LPA for the rapid detection of DR-TB. Furthermore, the need for quality assurance associated with the GenoType®MTBDRplus LPA in the diagnostic laboratory is essential and thus a user manual for the molecular detection of Drug Resistant Tuberculosis in resource-limited settings has also been developed (http://www.finddiagnostics.org/export/sites/default/resource-center/reports brochures/docs/LPA LaboratoryManual22Mar2012.pdf) for which Global Laboratory Initiative (GLI) status is pending. With the outbreak of extensively drug resistant TB (XDR-TB) in Tugela Ferry area in KwaZulu-Natal and the rest of the world, the need to rapidly detect resistance to the second line drugs arose, and thus the performance characteristics of the GenoType®MTBDRsl LPA was assessed for use on smear positive direct patient material. The performance characteristics proved to be excellent once again, with a 93.3% reduction in TAT. The data was scrutinized by the WHO, where it may be used as a triage test to guide treatment, but to date, no final policies on the use thereof has been finalized. The need for rapid point-of-care (POC) testing led to the implementation of the Xpert®MTB/RIF assay in the referral laboratories, for use on both smear positive and smear negative direct patient material. In order to accommodate for laboratories where the LPA has been implemented already, the GenoType®MTBDRplus Ver2.0 LPA was developed, which is aimed for use on all smear types as well. A head-to-head assessment was done between these assays to determine their performance characteristics and it was shown to be equally good. In this study we have shown the utility of molecular diagnostic assays to rapidly diagnose TB and its associated drug susceptibility patterns. This will have a significant impact on diagnostic delay and clinical decision making as well as patient outcome.