RESUMO
ABSTRACT Objective: The high-grade level of smear acid-resistant bacilli (ARB) positivity has been linked to increased infectiousness in pulmonary tuberculosis (TB). The ability to predict infectiousness is important in the management of the disease. The present study aimed to investigate the relationship between smear results, the clinical features, and the levels of radiological involvement of TB. Methods: A total of 245 cases diagnosed with pulmonary TB were admitted to the study. Data including age, sex, case definition, numbers and characteristics of symptoms, smear results, smear positivity grades, and levels of radiological involvement were recorded. Relations between smear results and other data were determined via cluster tree and regression analysis. Results: The group with only coughing had higher rates of both positive smear and high smear positivity levels (p = 0.014 and p = 0.02, respectively) compared to the group without coughing. Similarly, the groups with moderate or high radiological involvement showed significantly higher rates of both positive smear and high smear positivity level when compared to the group exhibiting low radiological involvement (p < 0.001). Conclusion: Patients with coughing and a moderate to high level of radiological involvement should be closely monitored due to their high-level risk of transmission.