Baseline Predictors of Sputum Culture Conversion in Pulmonary Tuberculosis: Importance of Cavities, Smoking, Time to Detection and W-Beijing Genotype

PLoS One

Gary Maartens¹  Gerhard Walzl²  Rob Warren³  Michael C. Stead³  Michael Schomaker³  Harleen M. S. Grewal⁴  Marianne E. Visser⁵  Elizabeth C. Swart⁶ 

[1] Division of Dietetics, University of the Western Cape, Cape Town, South Africa;Division of Medical Microbiology, Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, Cape Town, South Africa;MRC Centre for Molecular and Cellular Biology, University of Stellenbosch, Cape Town, South Africa;School of Public Health and Family Medicine, Centre for Infectious Disease Epidemiology and Research, University of Cape Town, Cape Town, South Africa;School of Public Health, University of the Western Cape, Cape Town, South Africa;Section of Microbiology and Immunology, The Gade Institute, University of Bergen, Haukeland University Hospital, Bergen, Norway

关键词: Sputum;    Tuberculosis;    Mycobacterium tuberculosis;    Smoking habits;    Tuberculosis diagnosis and management;    Isoniazid;    Primary care;    South Africa;   

DOI  :  10.1371/journal.pone.0029588

学科分类：医学（综合）

来源: Public Library of Science

【 摘 要 】

Background Time to detection (TTD) on automated liquid mycobacterial cultures is an emerging biomarker of tuberculosis outcomes. The M. tuberculosis W-Beijing genotype is spreading globally, indicating a selective advantage. There is a paucity of data on the association between baseline TTD and W-Beijing genotype and tuberculosis outcomes. Aim To assess baseline predictors of failure of sputum culture conversion, within the first 2 months of antitubercular therapy, in participants with pulmonary tuberculosis. Design Between May 2005 and August 2008 we conducted a prospective cohort study of time to sputum culture conversion in ambulatory participants with first episodes of smear and culture positive pulmonary tuberculosis attending two primary care clinics in Cape Town, South Africa. Rifampicin resistance (diagnosed on phenotypic susceptibility testing) was an exclusion criterion. Sputum was collected weekly for 8 weeks for mycobacterial culture on liquid media (BACTEC MGIT 960). Due to missing data, multiple imputation was performed. Time to sputum culture conversion was analysed using a Cox-proportional hazards model. Bayesian model averaging determined the posterior effect probability for each variable. Results 113 participants were enrolled (30.1% female, 10.5% HIV-infected, 44.2% W-Beijing genotype, and 89% cavities). On Kaplan Meier analysis 50.4% of participants underwent sputum culture conversion by 8 weeks. The following baseline factors were associated with slower sputum culture conversion: TTD (adjusted hazard ratio (aHR) = 1.11, 95% CI 1.02; 1.2), lung cavities (aHR = 0.13, 95% CI 0.02; 0.95), ever smoking (aHR = 0.32, 95% CI 0.1; 1.02) and the W-Beijing genotype (aHR = 0.51, 95% CI 0.25; 1.07). On Bayesian model averaging, posterior probability effects were strong for TTD, lung cavitation and smoking and moderate for W-Beijing genotype. Conclusion We found that baseline TTD, smoking, cavities and W-Beijing genotype were associated with delayed 2 month sputum culture. Larger studies are needed to confirm the relationship between the W-Beijing genotype and sputum culture conversion.

【 授权许可】

CC BY