Radiological difference between new sputum-positive and sputum-negative pulmonary tuberculosis

Introduction: The current guidelines for the diagnosis of pulmonary tuberculosis (PTB) are based primarily on the demonstration of acid-fast bacilli (AFB) on sputum microscopy and chest radiograph. Knowing various radiological manifestations and their association with sputum microscopy findings can allow for early diagnosis and early initiation of treatment. Aims: This study was performed to compare the chest radiograph features seen in sputum-positive and sputum-negative tuberculosis patients, respectively. Materials and Methods: It was a prospective observational study, which included 147 consecutive patients newly diagnosed and treated as PTB between Jan 2018 and July 2018. Chest X-ray was reviewed by 2 independent radiologists and the findings were compared between sputum-positive and sputum-negative PTB cases. The obtained data were analyzed by statistics using SPSS version 15 for Windows (SPSS Inc., Chicago, IL) and chi 2 test and Student t test were used for statistical analysis. P values < 0.05 were considered statistically significant. Results: Out of a total of 147 patients, 38 (25 males and 13 females, mean age 35.23 <plus/minus> 18.40) were sputum positive and 109 (77 males and 32 females, mean age 36.07 +/- 18.15) were sputum negative. The frequency of patchy consolidation (78.94% vs 49.54%) and cavitation (36.84% vs 15.59%) was significantly higher in sputum-positive PTB (P < 0.05). Radiological lesions like nodular shadow (10.09% vs 2.63%), cystic lesion (13.76% vs 5.26%), fibrosis (12.84% vs 7.89%), miliary shadows (2.75% vs 2.63%), and pleural effusion (1.83% vs 0%) were seen more commonly with sputum-negative PTB but the difference was not statistically significant for any of these features. Sputum-positive PTB tends to occur more commonly on the left side (47.36%) compared with sputum-negative PTB (27.52%) (P < 0.05). 34.21% and 35.77% of the chest X-ray lesions were bilateral in sputum-positive and sputum-negative PTB, respectively. Conclusion: Patchy infiltration and cavitation on chest X-ray are seen more frequently in sputum-positive cases of PTB compared with sputum-negative cases.