Comparative chest computed tomography findings of non-tuberculous mycobacterial lung diseases and pulmonary tuberculosis in patients with acid fast bacilli smear-positive sputum

BMC Pulmonary Medicine, Apr 2014

Background Early diagnosis and treatment of nontuberculous mycobacterial lung diseases (NTM-LD) and pulmonary tuberculosis (PTB) are important clinical issues. The present study aimed to compare and identify the chest CT characteristics that help to distinguish NTM lung disease from PTB in patients with acid-fast bacilli (AFB) smear-positive sputum. Methods From January 2009 to April 2012, we received 467 AFB smear-positive sputum specimens. A total of 95 CT scans obtained from the 159 patients were analyzed, 75 scans were from patients with PTB and 20 scans from NTM-LD. The typical chest CT findings of mycobacterial diseases were analyzed. Results In patients with PTB, the prevalence of pleural effusion (38.7% vs. 15.0%; P =0.047), nodules < 10 mm in size (76.0% vs. 25.0%; P < 0.001), tree-in-bud pattern (81.3% vs. 55.0%; P =0.021), and cavities (31.1% vs. 5.0%; P =0.018) were significantly higher than patients with NTM. Of the 20 patients with NTM lung diseases, bronchiectasis and cystic changes were significantly higher than patients with PTB (20.0% vs. 4.0%; P = 0.034). In multivariate analysis, CT scan findings of nodules was independently associated with patients with diagnoses of PTB (odds ratio [OR], 0.07; 95% confidence interval [CI], 0.02-0.30). Presence of bronchiectasis and cystic changes in CT scans was strongly associated with patients with NTM-LD (OR, 33.04; 95% CI, 3.01-362.55). Conclusions The CT distinction between NTM-LD and PTB may help radiologists and physicians to know the most likely diagnoses in AFB-smear positive patients and avoid unnecessary adverse effects and the related costs of anti-TB drugs in endemic areas.

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Comparative chest computed tomography findings of non-tuberculous mycobacterial lung diseases and pulmonary tuberculosis in patients with acid fast bacilli smear-positive sputum

BMC Pulmonary Medicine Comparative chest computed tomography findings of non-tuberculous mycobacterial lung diseases and pulmonary tuberculosis in patients with acid fast bacilli smear-positive sputum Mei-Kang Yuan 1 Cheng-Yu Chang Ping-Huang Tsai 1 2 Yuan-Ming Lee Jen-Wu Huang Shih-Chieh Chang 1 2 0 152 , Xin-Min Road, Yilan City 260 , Taiwan 1 Faculty of Medicine, School of Medicine, National Yang-Ming University , Taipei , Taiwan 2 Department of Internal Medicine, National Yang-Ming University Hospital Background: Early diagnosis and treatment of nontuberculous mycobacterial lung diseases (NTM-LD) and pulmonary tuberculosis (PTB) are important clinical issues. The present study aimed to compare and identify the chest CT characteristics that help to distinguish NTM lung disease from PTB in patients with acid-fast bacilli (AFB) smear-positive sputum. Methods: From January 2009 to April 2012, we received 467 AFB smear-positive sputum specimens. A total of 95 CT scans obtained from the 159 patients were analyzed, 75 scans were from patients with PTB and 20 scans from NTM-LD. The typical chest CT findings of mycobacterial diseases were analyzed. Results: In patients with PTB, the prevalence of pleural effusion (38.7% vs. 15.0%; P =0.047), nodules < 10 mm in size (76.0% vs. 25.0%; P < 0.001), tree-in-bud pattern (81.3% vs. 55.0%; P =0.021), and cavities (31.1% vs. 5.0%; P =0.018) were significantly higher than patients with NTM. Of the 20 patients with NTM lung diseases, bronchiectasis and cystic changes were significantly higher than patients with PTB (20.0% vs. 4.0%; P = 0.034). In multivariate analysis, CT scan findings of nodules was independently associated with patients with diagnoses of PTB (odds ratio [OR], 0.07; 95% confidence interval [CI], 0.02-0.30). Presence of bronchiectasis and cystic changes in CT scans was strongly associated with patients with NTM-LD (OR, 33.04; 95% CI, 3.01-362.55). Conclusions: The CT distinction between NTM-LD and PTB may help radiologists and physicians to know the most likely diagnoses in AFB-smear positive patients and avoid unnecessary adverse effects and the related costs of anti-TB drugs in endemic areas. Nontuberculous mycobacterial lung disease; Pulmonary tuberculosis; Acid-fast bacilli smear; Bronchiectasis and cystic changes - Background The diagnosis and treatment of pulmonary diseases caused by mycobacterial infections are very important clinical issues. Among mycobacterial diseases, pulmonary tuberculosis (PTB) is the major entity and one of the worlds leading infectious diseases. In 2012, 8.6 million people felt ill with TB and 1.3 million died from TB [1]. Isolation of Mycobacterium tuberculosis from respiratory specimens is recommended for the definite diagnosis of PTB [2]. Microscopic examination of sputum smears for acid-fast bacilli (AFB) is widely used and the most efficient procedure for the initial screening of PTB. The presence of AFB in the stained sputum (AFB smear-positive) indicates a preliminary diagnosis of pulmonary mycobacterial infection. However, positive AFB smear test is not specific for PTB [3-5]. AFB smear-positive sputum may represent mycobacterium tuberculosis, but it can also represent non-tuberculous mycobacteria (NTM) [6]. NTM are ubiquitous organisms and its radiographic abnormalities and clinical symptoms changes slowly as compared with PTB [7]. In endemic areas, it is not uncommon to administer empirical anti-TB drugs in clinically suspected PTB patients with AFB smear-positive sputum. The isolation prevalence of NTM has increased gradually, which raise the concerns of unnecessary adverse effect and costs of anti-TB drugs [8,9]. Therefore, additional diagnostic tools that help differentiate PTB and NTM is relevant in patients pending culture results. Radiological manifestations such as computed tomography (CT) features are useful to aid the diagnosis of PTB and NTM before definite mycobacterial culture because of its great availability and short examination time [10]. The aim of this study is to compare and identify the chest CT characteristics that help to distinguish NTM lung disease from PTB in patients with AFB smear-positive sputum. Methods Patients From January 2009 to April 2012, we received 9,267 sputum specimens from 3,958 patients at the laboratory of National Yang-Ming University Hospital (a 512-bed regional teaching hospital in Yilan, Taiwan) and the Far Eastern Memorial Hospital (a 1050-bed tertiary medical center in Taipei, Taiwan). Of these sputum specimens, 467 from 236 patients were AFB stain-positive. Only 134 of the AFB stain-positive patients had proven pulmonary TB, and 25 patients proven NTM lung diseases. A total of 95 CT scans obtained from the 159 patients were analyzed, 75 scans were from patients with PTB and 20 scans from NTM lung disease. The study was approved by the Institutional Review Boards of the National YangMing University Hospital and the Far Eastern Memorial Hospital. All participant (...truncated)


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Mei-Kang Yuan, Cheng-Yu Chang, Ping-Huang Tsai, Yuan-Ming Lee, Jen-Wu Huang, Shih-Chieh Chang. Comparative chest computed tomography findings of non-tuberculous mycobacterial lung diseases and pulmonary tuberculosis in patients with acid fast bacilli smear-positive sputum, BMC Pulmonary Medicine, 2014, pp. 65, 14, DOI: 10.1186/1471-2466-14-65