Browsing by Author "Van Zyl-Smit, Richard N."

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    Chronic obstructive pulmonary disease in South Africa : under-recognised and undertreated
    (Health & Medical Publishing Group, 2015) Allwood, Brian W.; Van Zyl-Smit, Richard N.
    Chronic obstructive pulmonary disease (COPD) is a common, preventable but incurable condition currently ranked third in global mortality estimates. Worldwide, 65 million people are estimated to have moderate to severe COPD, and the disease accounts for 3 million deaths annually, of which 90% are said to occur in low- and middle-income countries. Yet, despite these staggering numbers, COPD remains both under-recognised and undertreated in most populations, also in South Africa (SA). There are many reasons for this, not least of which is the attitude of clinicians, which can often be fatalistic with regard to COPD. This edition of CME highlights key aspects of the diagnosis and treatment – pharmacological and non-pharmacological – and new developments in the management of severe disease. Furthermore, we have included articles focusing on non-smokingrelated COPD and tips for good spirometry.
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    Comparison of quantitative techniques including Xpert MTB/RIF to evaluate mycobacterial burden
    (PLOS, 2011-12) Van Zyl-Smit, Richard N.; Binder, Anke; Meldau, Richard; Mishra, H.; Semple, P. L.; Theron, G.; Peter, J.; Whitelaw, A.; Sharma, S. K.; Warren, Rob; Bateman, E. D.; Dheda, K.
    Introduction: Accurate quantification of mycobacterial load is important for the evaluation of patient infectiousness, disease severity and monitoring treatment response in human and in-vitro laboratory models of disease. We hypothesized that newer techniques would perform as well as solid media culture to quantify mycobacterial burden in laboratory specimens. Methods: We compared the turn-around-time, detection-threshold, dynamic range, reproducibility, relative discriminative ability, of 4 mycobacterial load determination techniques: automated liquid culture (BACTEC-MGIT-960), [3H]-uracil incorporation assays, luciferase-reporter construct bioluminescence, and quantitative PCR(Xpert -MTB/RIF) using serial dilutions of Mycobacterium bovis and Mycobacterium tuberculosis H37RV. Mycobacterial colony-forming-units(CFU) using 7H10-Middlebrook solid media served as the reference standard. Results: All 4 assays correlated well with the reference standard, however, bioluminescence and uracil assays had a detection threshold $16103 organisms. By contrast, BACTEC-MGIT-960 liquid culture, although only providing results in days, was user-friendly, had the lowest detection threshold (,10 organisms), the greatest discriminative ability (1 vs. 10 organisms; p = 0.02), and the best reproducibility (coefficient of variance of 2% vs. 38% compared to uracil incorporation; p = 0.02). Xpert-MTB/RIF correlated well with mycobacterial load, had a rapid turn-around-time (,2 hours), was user friendly, but had a detection limit of ,100 organisms. Conclusions: Choosing a technique to quantify mycobacterial burden for laboratory or clinical research depends on availability of resources and the question being addressed. Automated liquid culture has good discriminative ability and low detection threshold but results are only obtained in days. Xpert MTB/RIF provides rapid quantification of mycobacterial burden, but has a poorer discrimination and detection threshold.
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    Transition from restrictive to obstructive lung function impairment during treatment and follow-up of active tuberculosis
    (Dove Medical Press, 2020) Allwood, Brian W.; Maasdorp, Elizna; Kim, Grace J.; Cooper, Christopher B.; Goldin, Jonathan; Van Zyl-Smit, Richard N.; Bateman, Eric D.; Dawson, Rodney
    Background: Pulmonary tuberculosis (PTB) is associated with many forms of chronic lung disease including the development of chronic airflow obstruction (AFO). However, the nature, evolution and mechanisms responsible for the AFO after PTB are poorly understood. The aim of this study was to examine the progression of changes in lung physiology in patients treated for PTB. Methods: Immunocompetent, previously healthy, adult patients receiving ambulatory treatment for a first episode of tuberculosis were prospectively followed up with serial lung physiology and quantitative computed tomography (CT) lung scans performed at diagnosis of tuberculosis, 2, 6, 12 and 18 months during and after the completion of treatment. Results: Forty-nine patients (median age 26 years; 37.2% males) were included, and 43 were studied. During treatment, lung volumes improved and CT fibrosis scores decreased, but features of AFO and gas trapping emerged, while reduced diffusing capacity (DLco) seen in a majority of patients persisted. Significant increases in total lung capacity (TLC) by plethysmography were seen in the year following treatment completion (median change 5.9% pred., P< 0.01) and were driven by large increases in residual volume (RV) (median change +19%pred., P< 0.01) but not inspiratory capacity (IC; P=0.41). The change in RV/TLC correlated with significant progression of radiological gas trapping after treatment (P=0.04) but not with emphysema scores. One year after completing treatment, 18.6% of patients had residual restriction (total lung capacity, TLC < 80%pred), 16.3% had AFO, 32.6% had gas trapping (RV/TLC> 45%), and 78.6% had reduced DLco. Conclusion: Simple spirometry alone does not fully reveal the residual respiratory impairments resulting after a first episode of PTB. Changes in physiology evolve after treatment completion, and these findings when taken together, suggest emergence of gas trapping after treatment likely caused by progression of small airway pathology during the healing process.