3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Viability of high performance liquid chromatography as a method of mycobacterial identification in South African laboratories(2001) Naidoo, ShironaPathogenic mycobacterial infection was in recent decades a health concern so well controlled that eradication seemed imminent. However, it is once again reaching epidemic proportions following the increasing prevalence of AIDS. One important means of curbing this resurgence, is a robust method that has the capability of identifying to a species level speciating disease causing mycobacteria in a matter of days. Several new methodologies are now available that enable dramatic reductions in turn-around times. In this study High Performance Liquid Chromatography was investigated to determine how this system compared with the current mycobacterial system of methodologies adopted in South African laboratories. Four species of pathogenic mycobacteria, with a high prevalence in South Africa, were tested in a sample size of 80. Samples were subjected to HPLC, Gene Probes and Biochemical testing. HPLC was the most capable of identifying the mycobacteria to species level displaying a sensitivity to the organisms of 96.25 %. Gene probes and Biochemical testing had sensitivity values of 82.5 % and 80 % respectively. HPLC was also more cost efficient and displayed a wider range of identification. It is therefore suggested that HPLC replace Gene probes and Biochemical testing for purposes of MOTT identification in the comprehensive mycobacterial identification system. The result is a time saving of at least 3 weeks and a cost reduction of approximately 30 %. The large initial capital investment required for the implementation of the HPLC system is justified by the long term cost saving as well as the additional utility derived from early identification. As a consequence treatment is not empiric but rather tailored to the organism infecting the patient, hence preventing multiple drug resistance developing and ultimately saving a life through rational drug use.Item The histopathological analysis of cellular elements, accessory molecules and cytokines in mycobacterial granulomas from HIV positive and negative individuals(2014-03-31) Wadee, ReubinaThe immune response to infection with Mycobacterium tuberculosis (Mtb) involves complex interactions between macrophages, T-cells, cytokines and accessory molecules. Mycobacteria evade the host’s immune response by interfering with cell mediated immune systems. Granulomas are central to the host’s defenses against Mtb. These responses may be modified by immune alterations especially in patients co-infected with Human Immunodeficiency Virus (HIV). This study investigated the immunohistochemical profile of CD4+, CD8+, CD68+, Th-17 (also known as Interleukin-17 cells) and Forkhead box (FOXP3) cells, accessory molecule expression (HLA Class I and II) and selected cytokines (Interleukin 2, 4, 6 and Interferon-) of various cell types within mycobacterial granulomas, in lymph nodes from ten HIV negative and ten HIV positive patients. Tissue from a foreign body granuloma in skin was utilised for comparison. This study illustrated retention of CD4+ lymphocyte numbers within granulomas from HIV negative (-) patients but documented a reversal in the ratio of CD4+ to CD8+cells in granulomas from HIV positive (+) patients. Similar IL-17 cell counts were noted in mycobacterial granulomas from both HIV (-) and HIV (+) patients. CD68 was identified in all macrophages and HLA Class II stained 100% of cells. Mycobacterial granulomas from HIV (-) patients showed marginally lower numbers of HLA Class I cells when compared to those from HIV (+) patients. The percentage of FOXP3 positive cells differed significantly between mycobacterial granulomas from HIV (-) and HIV (+) patients. This study highlights the complex interplay between different cell types and cytokines secreted into the microenvironment that ultimately results in containment of the organism or disease progression. Tuberculosis mono-infection causes variation in the expression of cell markers such as FOXP3 with accompanying noteworthy changes in cytokine production in areas of granuloma formation. The alterations noted in TB and HIV co-infection are even greater and point toward evolution of micro-organism synergism with host demise.