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Free Content Radiological cavitation, sputum mycobacterial load and treatment response in pulmonary tuberculosis

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SETTING: Royal Free Hospital, London.

OBJECTIVE: To investigate the relationship between sputum mycobacterial load, assessed by time to positivity (TTP) in liquid culture, radiological cavitation and change in sputum bacterial load in response to anti-tuberculosis treatment.

DESIGN: The study was conducted on 95 patients treated for sputum culture-positive pulmonary tuberculosis (TB), with pre-treatment TTP and baseline chest X-ray (CXR). Of these, 31 had chest computed tomography scans assessed for number and volume of cavities. The microbiological treatment response was measured in 56 patients with serial TTP, and related to baseline radiological cavitation.

RESULTS: Cavitation was present in 48% of patients, and was associated with a shorter TTP at baseline (P < 0.001). Patients with more cavities and greater total cavitary volume had a shorter TTP (P < 0.001 for both). No difference was demonstrated in the rate of change in TTP on treatment (P = 0.36) between patients with and without cavities.

CONCLUSION: This study confirms that cavitation is associated with higher baseline sputum mycobacterial load. The rate of decline in bacterial load in response to treatment is similar in patients with and without radiologically demonstrable cavities, suggesting that response to, and hence duration of, effective treatment may be predicted by the initial number of organisms present in the sputum.

Keywords: BacT/ALERT® 3D Mycobacteria detection systems; chest CT; chest X-ray; sputum mycobacterial load; time to culture positivity

Document Type: Regular Paper

Affiliations: 1: Department of Infection, Royal Free Campus, University College London, London, UK; and Department of Thoracic Medicine, Royal Free Hospital, London, UK 2: Department of Radiology, Royal Free Hospital, London, UK 3: Medical Research Council Clinical Trials Unit, London, UK 4: Department of Infection, Royal Free Campus, University College London, London, UK 5: Department of Thoracic Medicine, Royal Free Hospital, London, UK

Publication date: 2010-12-01

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  • The International Journal of Tuberculosis and Lung Disease publishes articles on all aspects of lung health, including public health-related issues such as training programmes, cost-benefit analysis, legislation, epidemiology, intervention studies and health systems research. The IJTLD is dedicated to the continuing education of physicians and health personnel and the dissemination of information on tuberculosis and lung health world-wide.

    Certain IJTLD articles are selected for translation into French, Spanish, Chinese or Russian. They are available on the Union website

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