Browsing by Author "Pillay, Melendhran."

Now showing 1 - 3 of 3

Matrix assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-TOF MS) proteomic profiling of mycobacteria.
Pillay, Melendhran.; Govender, Patrick.
Mycobacterium tuberculosis still remains a major cause of tuberculosis(TB) and death. In addition, nontuberculous mycobacteria (NTM) play a significant role in the aetiology of tuberculosis-like syndromes. A diagnosis of M. tuberculosis as the causative agent of pulmonary TB using only clinical symptoms may be inadequate and inaccurate in some cases since M.bovis, M.avium, M.kansasii, and M.intracellulare may all produce a pulmonary disease in humans that may be indistinguishable from that caused by M.tuberculosis. For diagnostic purposes, current mycobacterial identification strategies to the species level primarily rely on phenotypic analysis, complex biochemical tests, cultivation on specific growth media and genotype analysis. However, the main disadvantages that are associated with these techniques include extensive processing times (6-12 weeks to confirm a positive identification) and misidentification. Both factors severely hinder the control and management of diseases associated with mycobacteria, particularly tuberculosis. Apart from an increased patient mortality, interpersonal transmission of mycobacterial infections may increase. This scenario will also result in the prescription of inappropriate anti-tubercular treatment regimes. The present study assesses the feasibility of using MALDI-TOF MS proteomic profiling as a rapid and precise technology to identify mycobacteria in Kwazulu-Natal, South Africa which is currently a global epicentre of mycobacterial-associated diseases. In this study a modified EFA protein extraction protocol that incorporates an initial cell envelope delipidation step was formulated and shown to produce mass spectra that were unique and highly reproducible. The spectra were used to create an independent main spectral profile reference library (CMEFAMSP) representing clinically relevant American Type Culture Collection (ATCC) mycobacterial strains. Interestingly, this proof of concept study clearly demonstrates that MALDI-TOF MS-based biotyping of mycobacteria using the CMEFA-MSP reference library correctly identified 11 blind-coded ATCC strains sourced from an autonomous facility to the genus and species level with 100% accuracy.In addition the CMEFA-MSP reference library was employed to differentiate 39 blind-coded clinical mycobacterial isolates. Importantly all CMEFA-derived samples of the 39 clinical mycobacterial isolates displayed log score values of ≥ 2.3 and were correctly identified to the species level. This strongly suggests that MALDITOF MS when used in conjunction with the CMEFA sample preparation protocol has potential as a simple and cost-effective alternative for the unambiguous identification of clinically important mycobacteria. Moreover, individual members of the MTBC and NTM groups used in this study were distinguished from each other.
Primary capreomycin resistance is common and associated with early mortality in patients with extensively drug-resistant tuberculosis in KwaZulu-Natal, South Africa.
(Wolters Kluwer., 2015) O’Donnell, Max Roe.; Pillay, Melendhran.; Pillay, Manormoney.; Werner, Lise.; Master, Iqbal.; Wolf, Allison.; Mathema, Barun.; Coovadia, Yacoob Mahomed.; Mlisana, Koleka Patience.; Horsburgh, Charles Robert.; Padayatchi, Nesri.
Abstract available in pdf.
Rifampicin mono-resistance in mycobacterium tuberculosis in KwaZulu-Natal, South Africa : A significant phenomenon in a high prevalence TB-HIV region.
(PLoS One, 2013) Coovadia, Yacoob Mahomed.; Mahomed, Sharana.; Pillay, Melendhran.; Werner, Lise.; Mlisana, Koleka Patience.
Setting: The dual epidemics of HIV-TB including MDR-TB are major contributors to high morbidity and mortality rates in South Africa. Rifampicin (RIF) resistance is regarded as a proxy for MDR-TB. Currently available molecular assays have the advantage of rapidly detecting resistant strains of MTB, but the GeneXpert does not detect isoniazid (INH) resistance and the GenoTypeMTBDRplus(LPA) assay may underestimate resistance to INH. Increasing proportions of rifampicin monoresistance resistance (RMR) have recently been reported from South Africa and other countries. Objective: This laboratory based study was conducted at NHLS TB Laboratory, Durban, which is the reference laboratory for culture and susceptibility testing in KwaZulu-Natal. We retrospectively determined, for the period 2007 to 2009, the proportion of RMR amongst Mycobacterium tuberculosis (MTB) isolates, that were tested for both RIF and INH, using the gold standard of culture based phenotypic drug susceptibility testing (DST). Gender and age were also analysed to identify possible risk factors for RMR. Design: MTB culture positive sputum samples from 16,748 patients were analysed for susceptibility to RIF and INH during the period 2007 to 2009. RMR was defined as MTB resistant to RIF and susceptible to INH. For the purposes of this study, only the first specimen from each patient was included in the analysis. Results: RMR was observed throughout the study period. The proportion of RMR varied from a low of 7.3% to a high of 10.0% [overall 8.8%]. Overall, males had a 42% increased odds of being RMR as compared to females. In comparison to the 50 plus age group, RMR was 37% more likely to occur in the 25–29 year age category. Conclusion: We report higher proportions of RMR ranging from 7.3% to 10% [overall 8.8%] than previously reported in the literature. To avoid misclassification of RMR, detected by the GeneXpert, as MDR-TB, culture based phenotypic DST must be performed on a second specimen, as recommended by the SA NDOH TB guidelines as well as WHO. We suggest that two sputum samples should be obtained at the first visit. The second sputum sample should be stored at 4uC. The latter sample is then readily available for performing additional DST (phenotypic or genotypic) for 2nd lines drugs, resulting in a decreased waiting period for DST results to become available.