Risk factors for failure to complete a course of latent tuberculosis infection treatment in Salvador, Brazil.

BACKGROUND: Although treatment of latent tuberculosis infection (LTBI) is an essential component of tuberculosis (TB) control in countries such as the United States, it is not widely practiced in most TB-endemic countries. OBJECTIVE: To examine the practice of and adherence to LTBI treatment in a high-risk population in Brazil. DESIGN: We followed household contacts (HHCs) of patients hospitalized with pulmonary TB in Salvador, Brazil, for 6 months after they initiated LTBI treatment with isoniazid (INH). HHCs were asked to return to the hospital once a month for 6 months for follow-up visits and INH refills. RESULTS: Of 101 HHCs who initiated LTBI treatment, 54 (53.5%) completed the 6-month regimen. The risk of treatment non-completion was significantly higher in HHCs who reported side effects to INH (RR 2.69, 95%CI 1.3-5.8, P = 0.01), and in those who had to take two buses for a one-way trip to the hospital (RR 1.8, 95%CI 1.01-3.3, P = 0.04). Of the 101 HHCs, 29 (28.7%) did not return for any follow-up visits; these HHCs were significantly more likely to have a 2-bus commute to the hospital compared to HHCs who completed treatment (OR 20.69, 95%CI 2.1-208.4, P = 0.01). CONCLUSION: Nearly 50% of HHCs at high risk for developing TB completed a 6-month course of LTBI treatment. Completion of LTBI treatment was most affected by medication intolerance and commuting difficulties for follow-up visits.

Immunoglobulin G response to mammalian cell entry 1A (Mce1A) protein as biomarker of active tuberculosis.

Cell wall components are major determinants of virulence of Mycobacterium tuberculosis and they contribute to the induction of both humoral and cell-mediated immune response. The mammalian cell entry protein 1A (Mce1A), in the cell wall of M. tuberculosis, mediates entry of the pathogen into mammalian cells. Here, we examined serum immunoglobulin levels (IgA, IgM and total IgG) against Mce1A as a potential biomarker for diagnosis and monitoring tuberculosis (TB) treatment response. Serum samples of 39 pulmonary TB patients and 65 controls (15 healthy household contacts, 19 latently infected household contacts, 13 non-TB and 18 leprosy patients) were screened by ELISA. The median levels of all immunoglobulin classes were significantly higher in TB patients when compared with control groups. The positive test results for IgA, IgM and total IgG were 62, 54 and 82%, respectively. For comparison, routine sputum smear examination diagnosed only 26 (67%) of 39 TB cases. Sensitivities of IgA, IgM and IgG test were 59, 51.3 and 79.5%, respectively, while the specificities observed were 77.3, 83.3 and 84.4%, respectively. A significant decrease compared with baseline was also shown after TB treatment. These results suggest that circulating total IgG antibody to Mce1A could be a complementary tool to diagnosis pulmonary TB.

Blood Cells and Interferon-Gamma Levels Correlation in Latent Tuberculosis Infection.

The Mycobacterium tuberculosis (M. tb) infection is largely spread in world's population. Most infected individuals develop latent tuberculosis infection (LTBI). Tuberculin skin test (TST) and interferon-gamma release assays (IGRAs) are the available tests to detect the infection. It has been reported that some individuals take a longer period of time to develop the infection than others with the same exposure level. It is suggested that the innate immunity, in which neutrophils have an important protective role, is responsible for this. Many hematologic abnormalities have been described as common findings during severe disease. To investigate if these changes are related to LTBI development and if they interfere in TST and IFN-γ production, we recruited 88 household contacts of tuberculosis (TB) pulmonary patients and compared blood cell counts with these tests' results. There were no statistically significant changes in hemoglobin, hematocrit, platelets, global leukocyte, neutrophils, basophils, eosinophils, typical lymphocytes, atypical lymphocytes, and monocytes counts between infected and noninfected individuals. Also, there was no correlation between TST or IGRA and blood cell counts. These results suggest that blood cell counts are not LTBI markers and do not interfere in TST results or IFN-γ levels obtained by IGRA.

Nocturnal hypoxemia in children and adolescents with cystic fibrosis.

OBJECTIVE: To determine the prevalence of nocturnal hypoxemia and its association with pulmonary function, nutritional status, sleep macrostructure, and obstructive respiratory events during sleep in a population of clinically stable children and adolescents with cystic fibrosis (CF). METHODS: This was a cross-sectional study involving 67 children and adolescents with CF between 2 and 14 years of age. All of the participants underwent polysomnography, and SpO2 was measured by pulse oximetry. We also evaluated the Shwachman-Kulczycki (S-K) scores, spirometry findings, and nutritional status of the patients. RESULTS: The study involved 67 patients. The mean age of the patients was 8 years. The S-K scores differed significantly between the patients with and without nocturnal hypoxemia, which was defined as an SpO2 < 90% for more than 5% of the total sleep time (73.75 ± 6.29 vs. 86.38 ± 8.70; p < 0.01). Nocturnal hypoxemia correlated with the severity of lung disease, FEV1 (rs = -0.42; p = 0.01), FVC (rs = -0.46; p = 0.01), microarousal index (rs = 0.32; p = 0.01), and apnea-hypopnea index (rs = 0.56; p = 0.01). CONCLUSIONS: In this sample of patients with CF and mild-to-moderate lung disease, nocturnal oxygenation correlated with the S-K score, spirometry variables, sleep macrostructure variables, and the apnea-hypopnea index.

Levels of interferon-gamma increase after treatment for latent tuberculosis infection in a high-transmission setting.

Objectives. We investigated IFN-γ levels before and after a six month course of isoniazid among individuals with latent tuberculosis infection (LTBI) in a high-transmission setting. Design. A total of 26 household contacts of pulmonary tuberculosis patients who were positive for LTBI by tuberculin skin test completed six months of treatment and submitted a blood sample for a follow-up examination. The IFN-γ response to Mycobacterium tuberculosis-specific antigens was measured, and the results before and after the completion of LTBI treatment were compared. Results. Of the 26 study participants, 25 (96%) showed an IFN-γ level higher than their baseline level before treatment (P ≤ 0.001). Only one individual had a decreased IFN-γ level after treatment but remained positive for LTBI. Conclusion. In a high-transmission setting, the IFN-γ level has increased after LTBI treatment. Further studies must be undertaken to understand if this elevation is transient.