Differences in pulmonary cavity features among drug-sensitive pulmonary tuberculosis and...

Pulmonary cavities (PC) are known to be more prevalent among multidrug-resistant pulmonary tuberculosis (MDR)/extensively drug-resistant tuberculosis (XDR) patients than among drug-sensitive tuberculosis (DS) patients. This study aims to clarify how the interaction between Mycobacterium tuberculosis aggressiveness and tuberculosis history causes the PC prevalence and pattern differences between DS patients and MDR/XDR patients.

Eastern European patient data were from the NIAID TB (National Institute of Allergy & Infectious Diseases Tuberculosis) Portals Program registered before January 2019. Chinese patients were from Shenzhen, China, treated between April 2017 and February 2019. There were in total 244 DS cases (222 new patients and 22 previously treated patients), 344 MDR cases (188 new patients and 156 previously treated patients), and 155 XDR cases (36 new patients and 119 previously treated patients). The first chest computed tomography (CT) images were analysed. PC were counted only for those with a lumen diameter >5 mm. Multiple cavities in a single consolidation were counted as one cavity. Calcified lesions in the lungs, as a sign of chronicity, were also recorded.

In new patients, there was no difference in lung lesion calcification prevalence among DS (13.5%), MDR (14.4%), and XDR (13.9%). In previously treated patients, lung calcification prevalence was 36.4% for DS, 44.9% for MDR, and 45.4% for XDR. For new patients, the PC prevalence was higher for MDR cases than for DS cases (41% vs. around 25%). For treated patients, PC prevalence increased to 36.4% for DS cases, to 57% for MDX cases, and to 71.4% for XDR cases. For new patients, the mean PC number for positive cases was DS: 1.66, MDR: 2.79, XDR: 2.69. For treated cases, the mean PC number for positive cases was DS: 2.13, MDR: 2.58, XDR: 2.47. For new patients, the mean PC diameter (in mm) for positive cases was DS: 15.4, MDR: 16.9, XDR: 17.5. For treated cases, the mean PC diameter (in mm) for positive cases was DS: 19.0, MDR: 20.8, XDR: 25.6. The number of lung fields with PC lesion was higher for MDR cases than for DS cases. PC number ≥2 had a specificity of around 92.3% for new patients, and around 81.0% for previously treated patients, suggesting the diagnosis of MDR/XDR.

MDR/XDR patients exhibit significantly higher PC prevalence and more extensive pulmonary involvement compared to DS patients, which are not totally determined by the length of disease history. Compared with literature reports, the prevalence of PC and the PC number per positive case were comparatively low in this study. Taking all results together, PC number ≥3 offers reasonable specificity for suggesting the diagnosis of MDR, though the sensitivity would be low.