3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item The role of the polymerase chain reaction in the routine haematology laboratory.(1993) Gunther, Karen ElizabethThe Polymerase Chain Reaction (PCR) provides a means of amplifying target sequences of DNA exponentially and it is rapidly becoming an indispensable tool in the research laboratory. Many other molecular genetic techniques used for research are far too laborious and expensive to be used for routine diagnostic purposes but PCR has the potential to be different. This Research Report assesses the possible role of PCR as a routine diagnostic tool in the haematology laboratory. In the context of haematology, PCR can be used to detect both "pathological" and "physiological" target sequences present within the genome. Pathological sequences of interest would include mutations, deletions, insertions or translocations not present within the normal genome but which may arise either as a result of an hereditary abnormality or be acquired somatically. Sensitive detection of such sequences is useful for diagnostic purposes and can also be relevant in determining prognosis, evaluating response to therapy and following up minimal residual disease in the context of haematological malignancies. PCR detectable physiological sequences would include the immunoglobulin and T cell receptor gene rearrangements normally present within the genome of cells of the appropriate lineage. These rearrangements differ for each lymphocyte within a polyclonal population but are identical among members of a clone arising by proliferation of a single precursor cell. They can therefore be of value not only in determining cell lineage but also as markers of clonality. In this study the practical aspects of using PCR were assessed by setting up the technique of amplification of immunoglobulin gene rearrangements. The cost of reagents and disposable equipment, as well as that of major items of equipment required which are not usually available in a routine laboratory was also determined. In addition, peripheral blood and bone marrow samples reaching the Haematology Laboratory of the Johannesburg Hospital were analysed to assess the potential demand for such investigations. Once appropriate reaction conditions for the primers used had been established, PCR was found to be quick, technically simple and relatively inexpensive. Sufficient numbers of appropriate samples for which PCR analysis could potentially be of value were received in the Johannesburg Hospital Haematology Laboratory in the periods assessed, to indicate that diagnostic PCR, if available, would be well utilised. Some problems were encountered, particularly with regard to variability in the extent of amplification obtained. Thus for routine diagnostic purposes, extensive research and development of each set of primers to be employed will be necessary to make the technique more reliable and consistent. Adequate quality control will also be essential if PCR is to be used for diagnostic purposes. However, once these issues have been addressed, PCR should definitely find a place as a routine diagnostic tool in the haematology laboratoryItem A cost analysis of the conventional culture method versus polymerase chain reaction testing for methicillin-resistant staphylococcus aureus at a South African public hospital(2016-10-12) Ahmed-Hassen, SadiyyaMethicillin-Resistant Staphylococcus aureus (MRSA) infections increase the cost and consequences of patient care within hospitals. Patients can be tested for MRSA using the Conventional Culture Method or new rapid Polymerase Chain Reaction (PCR) tests, such as the Xpert MRSA test. International studies have compared the costs and consequent management pathways for these two methods of MRSA testing. However, in the South African context where socio-economic status and access to healthcare may contribute different influences, no such models exist. Therefore, the aim of this study was to investigate the costs of the management pathways associated with using the current Conventional Culture Method for MRSA testing, to construct decision-tree-analytic models and compare them to the new PCR testing, in order to inform decision-making. TreeAge decision-tree-analytic models were developed to depict the current pathways, and associated costs, incurred by patients with a suspected MRSA infection in an orthopaedic and vascular ward at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) in South Africa in 2013. These models were then compared to theoretical pathways including implementing the Xpert MRSA. The models were populated with input parameters from observations conducted in the two wards, the microbiology laboratory and the main dispensary, and costs were calculated using the retrospective utilization reviews formulated from the antibiotics administered and laboratory tests that isolated MRSA in the study population. Sensitivity analyses were performed to evaluate the effect of the variables on the models. The average total cost of antibiotics and MRSA laboratory tests utilised per patient in the orthopaedic and vascular wards were R3 846.82 and R2 964.39 respectively. Based on ethnographic observations and retrospective utilization reviews, three pathways for a patient with a suspected infection were identified: Empiric Antibiotics followed by Microscopy, Culture and Sensitivity (MCS); MCS followed by Empiric Antibiotics; Empiric Antibiotics and MCS concurrently. The fourth pathway included implementing the Xpert MRSA test. Analysis of these pathways revealed that implementation of the Xpert MRSA would be the optimal strategy in the orthopaedic ward, but the most expensive strategy in the vascular ward. In conclusion, these costs and pathways highlight the utilization of scarce resources. Thus, it is suggested that, before new methods of MRSA testing are introduced, the current practices and pathways for patients with a suspected MRSA infection should be further evaluated and improved.