Baseline predictors of sputum culture conversion in pulmonary tuberculosis : importance of cavities, smoking, time to detection and W-Beijing genotype

dc.contributor.authorVisser, Marianne E.en_ZA
dc.contributor.authorStead, Michael C.en_ZA
dc.contributor.authorWalzl, Gerharden_ZA
dc.contributor.authorWarren, Roben_ZA
dc.contributor.authorSchomaker, Michaelen_ZA
dc.contributor.authorGrewal, Harleen M. S.en_ZA
dc.contributor.authorSwart, Elizabeth C.en_ZA
dc.contributor.authorMaartens, Garyen_ZA
dc.identifier.citationVisser M. E., Stead M. C., Walzl G. Warren R. Schomaker M. et al. (2012) Baseline Predictors of Sputum Culture Conversion in Pulmonary Tuberculosis: Importance of Cavities, Smoking, Time to Detection and W-Beijing Genotype. PLoS ONE 7(1): e29588.en_ZA
dc.description.abstractBackground: 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.en_ZA
dc.format.extent7 p. : ill.
dc.subjectMycobacterial culturesen_ZA
dc.subjectTime to detection (TTD)en_ZA
dc.subjectM. tuberculosis W-Beijing genotypeen_ZA
dc.subjectSputum culture conversionen_ZA
dc.subjectGenotype-environment interactionen_ZA
dc.subjectMycobacterium tuberculosis -- Diagnosisen_ZA
dc.subjectW-Beijing genotypeen_ZA
dc.titleBaseline predictors of sputum culture conversion in pulmonary tuberculosis : importance of cavities, smoking, time to detection and W-Beijing genotypeen_ZA
dc.description.versionPublisher's versionen_ZA
dc.rights.holderThe authors holds the copyrighten_ZA

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