Circulating microparticles from subjects with active pulmonary tuberculosis infection modulate immune response.

Microparticles (MPs) which circulate within the plasma are elevated in patients with active pulmonary tuberculosis infection. Circulating MPs isolated from the plasma of patients with active pulmonary tuberculosis infection modulate the cytokine production of immune cells in vitro.

Prevalence of latent tuberculosis infection and risk of infection in patients with chronic kidney disease undergoing hemodialysis in a referral center in Brazil.

OBJECTIVE: To determine the prevalence of latent tuberculosis infection (LTBI) and the risk of infection in patients with chronic kidney disease treated at a hemodialysis center. METHODS: We included 307 patients with chronic kidney disease undergoing hemodialysis at the Mineiro Institute of Nephrology, located in the city of Belo Horizonte, Brazil. All of the patients were submitted to tuberculin skin tests (TSTs). We investigated the booster effect and TST conversion. If the initial TST (TST1) was negative, a second TST (TST2) was performed 1-3 weeks later in order to investigate the booster effect. If TST2 was also negative, a third TST (TST3) was performed one year after TST2 in order to determine whether there was TST conversion. RESULTS: When we adopted a cut-off induration of 5 mm, the prevalence of LTBI was 22.2% on TST1, increasing by 11.2% on TST2. When we adopted a cut-off induration of 10 mm, the prevalence of LTBI was 28.5% on TST1, increasing by 9.4% on TST2. The prevalence of LTBI increased significantly from TST1 to TST2 (booster effect), as well as from TST2 to TST3 (p < 0.01 for both). In our sample, the mean annual risk of infection was 1.19%. CONCLUSIONS: In the population studied, the prevalence of LTBI was high, and the mean annual risk of infection was similar to that reported for the general population of Brazil, which suggests recent infection.

CD4-CD8-αß and γδ T cells display inflammatory and regulatory potentials during human tuberculosis.

T-cells play an important role controlling immunity against pathogens and therefore influence the outcome of human diseases. Although most T-lymphocytes co-express either CD4 or CD8, a smaller T-cell subset found the in the human peripheral blood that expresses the αß or γδ T-cell-receptor (TCR) lacks the CD4 and CD8 co-receptors. These double negative (DN) T-cells have been shown to display important immunological functions in human diseases. To better understand the role of DN T-cells in human Mycobacterium tuberculosis, we have characterized their frequency, activation and cytokine profile in a well-defined group of tuberculosis patients, categorized as severe and non-severe based on their clinical status. Our data showed that whereas high frequency of αß DN T-cells observed in M. tuberculosis-infected patients are associated with disease severity, decreased proportion of γδ DN T-cells are found in patients with severe tuberculosis. Together with activation of CD4(+) and CD8(+) T-cells, higher frequencies of both αß and γδ DN T-cells from tuberculosis patients also express the chronic activation marker HLA-DR. However, the expression of CD69, an early activation marker, is selectively observed in DN T-cells. Interestingly, while αß and γδ DN T-cells from patients with non-severe tuberculosis display a pro-inflammatory cytokine profile, characterized by enhanced IFN-γ, the γδ DN T-cells from patients with severe disease express a modulatory profile exemplified by enhanced interleukin-10 production. Overall, our findings suggest that αß and γδ DN T-cell present disparate immunoregulatory potentials and seems to contribute to the development/maintenance of distinct clinical aspects of TB, as part of the complex immunological network triggered by the TB infection.

Utilization of bacteriological culture for increased diagnostic performance at a tuberculosis reference center hospital.

The purpose of this study was to assess the increase in positive results of bacteriological diagnostic tests for tuberculosis with the utilization of culture at a referral hospital for tuberculosis (TB). A retrospective analysis was conducted based on the positive bacteriological results obtained at the Júlia Kubistchek Hospital. The number of bacteriological diagnoses was increased by 24.6 % with the utilization of culture of sputum samples and by 56.1% of bronchoalveolar lavage samples. With regard to pleural fluid, all six positive cultures were negative for bacilloscopy. Mycobacterium tuberculosis was isolated in 59.6 % of positive cultures. Since mycobacterial culture was not undertaken for all clinical samples, this procedure is an important laboratory routine at the Júlia Kubistchek Hospital in order to learn the real TB prevalence.

Positive tuberculin test and risk of infection by Mycobacterium tuberculosis in a tuberculosis clinic settled in an upright building, in Minas Gerais, Brazil / Reactividad a tuberculina en trabajadores de la salud de un centro de referencia de tuberculosis

Background: Occupational Tuberculosis (TB) can lead to work absenteeism and a negative professional impact. Knowing the reactivity of the tuberculin test and the risk of M. tuberculosis infection among healthcare professionals is essential for the revision and reinforcement of control measures against TB transmission. Aim: To assess the reactivity of tuberculin test and risk of M. tuberculosis infection among healthcare professionals working in an upright building, in which a TB Reference Clinic is placed. Subjects and Methods: A tuberculosis Skin Test (TST) was done to 251 staff members of a TB clinic that did not have a previous history or suspicion of TB and that did not have a previous TST done. Among subjects with absence of reaction, repeated tests were carried out to assess booster reaction. Results: Fifty one percent of studied subjects (129) had a positive tuberculin test. The booster phenomenon was evidenced in 35.7% (68/190). The seroconversion among non-reactive subjects, subjected to a new TST after one year, was 5.1%. The infection risk was 1.4. Conclusions: This study indicates an important occupational risk of infection in healthcare settings exposed to high TB incidence, and should be used to better allocate resources for infection control.

Antecedentes: La tuberculosis ocupacional causa ausentismo laboral. Conocer la reactividad tuberculínica de los trabajadores de la salud ayuda a mejorar las medidas de control para evitar la infección laboral con M. tuberculosis. Objetivo: Estudiar la reactividad tuberculínica de un grupo de trabajadores de la salud de un centro de referencia de tuberculosis que está ubicado en una edificación vertical. Material y Métodos: Se realizó una prueba de tuberculina a 251 empleados de una clínica de tuberculosis, que no tenían antecedentes o sospecha de tuberculosis y quienes no habían sido sometidos previamente a la prueba. Aquellos sujetos que no respondieron a tuberculina fueron sometidos a una nueva prueba para evaluar la reacción de refuerzo. Resultados: El 51% de los sujetos estudiados tuvieron una reacción tuber-culínica positiva. El fenómeno de refuerzo se observó en 69 de 190 sujetos (35,7%). La tasa de seroconversión en aquellos sujetos con una tuberculina negativa en que se repitió la prueba la cabo de un año, fue de 5,1%. Conclusiones: En este grupo de trabajadores de la salud expuestos a M. tuberculosis, hay una alta tasa de reactividad negativa a tuberculina.

Positive tuberculin test and risk of infection by Mycobacterium tuberculosis in a tuberculosis clinic settled in an upright building, in Minas Gerais, Brazil.

BACKGROUND: Occupational Tuberculosis (TB) can lead to work absenteeism and a negative professional impact. Knowing the reactivity of the tuberculin test and the risk of M. tuberculosis infection among healthcare professionals is essential for the revision and reinforcement of control measures against TB transmission. AIM: To assess the reactivity of tuberculin test and risk of M. tuberculosis infection among healthcare professionals working in an upright building, in which a TB Reference Clinic is placed. SUBJECTS AND METHODS: A tuberculosis Skin Test (TST) was done to 251 staff members of a TB clinic that did not have a previous history or suspicion of TB and that did not have a previous TST done. Among subjects with absence of reaction, repeated tests were carried out to assess booster reaction. RESULTS: Fifty one percent of studied subjects (129) had a positive tuberculin test. The booster phenomenon was evidenced in 35.7% (68/190). The seroconversion among non-reactive subjects, subjected to a new TST after one year, was 5.1%. The infection risk was 1.4. CONCLUSIONS: This study indicates an important occupational risk of infection in healthcare settings exposed to high TB incidence, and should be used to better allocate resources for infection control.

Tuberculous uveitis at a referral center in southeastern Brazil.

OBJECTIVE: To describe the occurrence of tuberculous uveitis (TBU) at a referral center in the state of Minas Gerais, Brazil. METHODS: A total of 16 consecutive patients (>15 years of age) who underwent diagnostic evaluation of uveitis between January of 2001 and July of 2004 at the Minas Gerais State Referral Center were selected for study. Demographic and clinical data, as well as data related to screening for toxoplasmosis, syphilis, and rheumatologic diseases, together with the results of tuberculin skin testing and HIV testing, were collected. RESULTS: Of the16 patients evaluated, 11 (69%) were found to have TBU. A history of contact with pulmonary tuberculosis was reported by 8 (72%) of the 11 patients with TBU and by 1 (20%) of the 5 with non-TBU. Although the odds ratio for this association was 10.67 (95% CI: 0.59-398.66), the p value was borderline significant (p = 0.078). There was no difference between the patients with TBU and those with non-TBU in terms of the status of ocular inflammation or the tuberculin skin testing results. All of the patients were HIV negative and were monitored for two years. CONCLUSION: In this study, a history of contact with pulmonary tuberculosis proved to be useful in diagnosing TBU.

Tuberculous uveitis at a referral center in southeastern Brazil / Uveíte por tuberculose em um centro de referência no Sudeste do Brasil

OBJETIVO: Descrever a ocorrência de uveíte por tuberculose (UTB) em um centro de referência em Minas Gerais, Brasil. MÉTODOS: Um total de 16 pacientes (idade > 15 anos) atendidos consecutivamente de janeiro de 2001 a julho de 2004 no Centro de Referência de Uveíte do Estado de Minas Gerais para avaliação diagnóstica de uveíte foi selecionado para este estudo. Foram coletados dados demográficos e clínicos, assim como dados sobre avaliação para toxoplasmose, sífilis e doenças reumatológicas, teste tuberculínico e sorologia anti-HIV. RESULTADOS: Dos 16 pacientes, 11 (69 por cento) tinham UTB. História prévia de contato com tuberculose pulmonar foi relatada por 72 por cento (8/11) dos pacientes do grupo com UTB e por 20 por cento (1/5) dos pacientes do grupo sem UTB. Embora a razão de chances para essa associação tenha sido de 10,67 (IC95 por cento: 0,59-398,66), o valor de p apresentou significância limítrofe (0,078). Não houve diferença quanto ao quadro ocular inflamatório e ao resultado do teste tuberculínico entre os pacientes com UTB e os sem UTB. Todos os pacientes tinham sorologia negativa para o HIV e foram acompanhados por 2 anos. CONCLUSÕES: Neste estudo, a história prévia de contato com tuberculose pulmonar foi de grande ajuda para o diagnóstico da UTB.

OBJECTIVE: To describe the occurrence of tuberculous uveitis (TBU) at a referral center in the state of Minas Gerais, Brazil. METHODS: A total of 16 consecutive patients (>15 years of age) who underwent diagnostic evaluation of uveitis between January of 2001 and July of 2004 at the Minas Gerais State Referral Center were selected for study. Demographic and clinical data, as well as data related to screening for toxoplasmosis, syphilis, and rheumatologic diseases, together with the results of tuberculin skin testing and HIV testing, were collected. RESULTS: Of the16 patients evaluated, 11 (69 percent) were found to have TBU. A history of contact with pulmonary tuberculosis was reported by 8 (72 percent) of the 11 patients with TBU and by 1 (20 percent) of the 5 with non-TBU. Although the odds ratio for this association was 10.67 (95 percent CI: 0.59-398.66), the p value was borderline significant (p = 0.078). There was no difference between the patients with TBU and those with non-TBU in terms of the status of ocular inflammation or the tuberculin skin testing results. All of the patients were HIV negative and were monitored for two years. CONCLUSION: In this study, a history of contact with pulmonary tuberculosis proved to be useful in diagnosing TBU.

Peripheral blood mononuclear cells immunophenotyping in pulmonary tuberculosis patients before and after treatment.

Tuberculosis (TB) is a lung disease caused by Mycobacterium tuberculosis. The interaction between the bacillus and the host may lead to a protective cellular immune response. In the present study, we propose the "in vitro" evaluation of this cellular immune response in patients with tuberculosis before and after chemotherapic treatment. Eleven patients with TB and 9 asymptomatic subjects with tuberculin skin test negative (TST-) (purified protein derivative (PPD)

Low-stringency single-specific-primer PCR as a tool for detection of mutations in the rpoB gene of rifampin-resistant Mycobacterium tuberculosis.

By the low-stringency single-specific-primer PCR technique, a highly sensitive and rapid method for diagnosis of rifampin resistance in Mycobacterium tuberculosis was established. Seven rifampin-resistant and five rifampin-susceptible specimens were analyzed. Rifampin resistance was determined by MIC measurement. A complex electrophoretic pattern consisting of many bands was obtained for both susceptible and rifampin-resistant isolates. The same pattern was obtained for all of the susceptible specimens, but differences between resistant and susceptible isolates were found. DNA sequencing showed that a particular mutation produces a specific electrophoretic pattern.