Research Article: Characteristics of Patients with Smear-Negative Pulmonary Tuberculosis (TB) in a Region with High TB and HIV Prevalence

Date Published: January 25, 2016

Publisher: Public Library of Science

Author(s): Leandro Cruz Campos, Marcos Vinícius Vieira Rocha, Denise Maria Cunha Willers, Denise Rossato Silva, Claire Thorne.

http://doi.org/10.1371/journal.pone.0147933

Abstract

Smear-negative pulmonary TB (SNPT) represents 30–60% of all pulmonary TB cases. The mortality of these patients can reach 25% in populations with high prevalence of HIV infection, and 10–20% of TB transmission at the population level are attributable to SNPT cases.

We conducted a retrospective study to evaluate epidemiological, clinical, and radiological characteristics of patients with SNPT and to compare these with patients who were diagnosed as having smear-positive pulmonary TB (SPPT). All adult patients (≥ 18 years old) with a positive culture for Mycobacterium tuberculosis, and a diagnosis of pulmonary TB were included in the study.

198 patients met the inclusion criteria (positive culture for Mycobacterium tuberculosis) and were included in the analysis. Of these patients, 69 (34.8%) were smear positive (SPPT) and 129 (65.2%) were smear negative (SNPT). In univariate analysis, cough, dyspnea, and hemoptysis were less frequent in SNPT patients in comparison with SPPT patients. In a multivariate model, having no cough and no radiographic pattern typical of TB were the characteristics independently associated with a diagnosis of SNPT.

We found a very high prevalence of SNPT among patients with TB in a setting with high TB and HIV prevalence. The absence of cough in the presence of other symptoms suggestive of TB, and having no radiographic pattern typical of TB where independent predictors of SNPT.

Partial Text

Pulmonary tuberculosis (TB) is still one of the most common infectious diseases in the world. It is the second leading cause of death from an infectious disease worldwide, after the human immunodeficiency virus (HIV) [1]. Brazil is ranked 16th among the 22 high-burden countries that collectively account for 80% of TB cases globally, with an incidence of 33.5 cases/100,000 inhabitants/year in 2014. The city of Porto Alegre has the highest incidence of TB in the country (99.3 cases/100,000 inhabitants/year in 2014), and 28.0% of TB patients are coinfected with HIV [2].

During the study period, 198 patients met the inclusion criteria [positive culture for Mycobacterium tuberculosis in spontaneous sputum (n = 49), induced sputum (n = 54), or bronchoalveolar lavage (n = 95)] and were included in the analysis. Out of these patients, 69 (34.8%) were smear positive (SPPT) and 129 (65.2%) were smear negative (SNPT). The characteristics of the study population are shown in Table 1.

In this retrospective study, we demonstrated a high prevalence of SNPT (65.2%) among patients with TB in a tertiary care hospital in a region with high TB and HIV prevalence. In univariate analysis, cough, dyspnea, and hemoptysis were less frequent in SNPT patients in comparison with SPPT patients. In addition, the median length of hospital stay was higher in SNPT patients than in SPPT patients. In a multivariate model, having no cough and no radiographic pattern typical of TB were the characteristics associated with a diagnosis of SNPT.

 

Source:

http://doi.org/10.1371/journal.pone.0147933