Tuberculosis infection among primary health care workers / Infecção por tuberculose entre profissionais de saúde da atenção básica

ABSTRACT Objective: To estimate the prevalence of and determine the risk factors associated with latent Mycobacterium tuberculosis infection (LTBI) among primary health care workers in the city of Vitória, Brazil. Methods: This was a cross-sectional study with data collected through a survey regarding socio-demographic, occupational, clinical, and exposure characteristics, as well as knowledge about tuberculosis, conducted between 2011 and 2012. All participants underwent a tuberculin skin test (TST), and TSTs were read at 72 h by a trained professional. Results: A total of 218 primary health care workers participated in the study. The prevalence of TST positivity at the ≥ 10-mm and ≥ 5-mm cut-off points was, respectively, 39.4% (95% CI: 32.9-45.9) and 54.1% (95% CI: 47.4-60.7). Regarding occupational categories, community health agents had the highest proportion of TST positivity, regardless of the cut-off point (≥ 10 mm: 47.5%; and ≥ 5 mm: 60.5%). Regarding factors associated with TST results, "having had a previous TST" showed a statistically significant association with TST positivity at the ≥ 10-mm and ≥ 5-mm cut-off points (OR = 2.5 [95% CI: 1.17-5.30] and OR = 2.18 [95% CI: 1.23-3.87], respectively). Conclusions: The prevalence of LTBI was found to be high among the primary health care workers in this sample. Therefore, we recommend the establishment of a periodic screening program for LTBI and implementation of effective biosafety policies for the prevention of this infection among primary health care workers.

RESUMO Objetivo: Estimar a prevalência de infecção latente pelo Mycobacterium tuberculosis (ILTB) e identificar os fatores de risco associados a essa infecção entre profissionais de saúde da atenção básica no município de Vitória (ES). Métodos: Estudo transversal cujas informações foram obtidas por meio de inquérito sobre dados sociodemográficos, ocupacionais, clínicos, de exposição e de conhecimento sobre tuberculose, realizado entre 2011 e 2012. Todos os participantes foram submetidos ao teste tuberculínico (TT), e a leitura do resultado foi realizada após 72 h por um profissional capacitado. Resultados: Participaram do estudo 218 profissionais de saúde. A prevalência de positividade ao TT foi de 39,4% (IC95%: 32,9-45,9) e de 54,1% (IC95%: 47,4-60,7), respectivamente, para os pontos de corte do TT ≥ 10 mm e ≥ 5 mm. Em relação às categorias profissionais, os agentes comunitários de saúde apresentaram a maior proporção de positividade ao teste, independentemente do ponto de corte considerado (≥ 10 mm: 47,5%; e ≥ 5 mm: 60,5%). Em relação aos fatores associados ao resultado do teste, "ter feito TT anteriormente" apresentou associações estatisticamente significativas com o resultado positivo ao TT para os pontos de corte ≥ 10 mm e ≥ 5 mm [OR = 2,5 (IC95%: 1,17-5,30) e OR = 2,18 (IC95%: 1,23-3,87), respectivamente]. Conclusões: Os profissionais de saúde da atenção básica dessa amostra apresentaram uma alta prevalência de ILTB. Logo, recomendam-se a instituição de um programa de triagem periódica para ILTB e a implantação de políticas efetivas de biossegurança para a prevenção dessa infecção nos profissionais de saúde na atenção básica.

Prevalence of latent Mycobacterium tuberculosis infection in prisoners / Prevalência da infecção latente por Mycobacterium tuberculosis em pessoas privadas de liberdade

ABSTRACT Objective: To determine the prevalence of and the factors associated with latent Mycobacterium tuberculosis infection (LTBI) in prisoners in the state of Minas Gerais, Brazil. Methods: This was a cross-sectional cohort study conducted in two prisons in Minas Gerais. Tuberculin skin tests were performed in the individuals who agreed to participate in the study. Results: A total of 1,120 individuals were selected for inclusion in this study. The prevalence of LTBI was 25.2%. In the multivariate analysis, LTBI was associated with self-reported contact with active tuberculosis patients within prisons (adjusted OR = 1.51; 95% CI: 1.05-2.18) and use of inhaled drugs (adjusted OR = 1.48; 95% CI: 1.03-2.13). Respiratory symptoms were identified in 131 (11.7%) of the participants. Serological testing for HIV was performed in 940 (83.9%) of the participants, and the result was positive in 5 (0.5%). Two cases of active tuberculosis were identified during the study period. Conclusions: Within the prisons under study, the prevalence of LTBI was high. In addition, LTBI was associated with self-reported contact with active tuberculosis patients and with the use of inhaled drugs. Our findings demonstrate that it is necessary to improve the conditions in prisons, as well as to introduce strategies, such as chest X-ray screening, in order to detect tuberculosis cases and, consequently, reduce M. tuberculosis infection within the prison system.

RESUMO Objetivo: Determinar a prevalência e os fatores associados à infecção latente por Mycobacterium tuberculosis (ILTB) em pessoas privadas de liberdade no Estado de Minas Gerais. Métodos: Estudo de coorte transversal realizado em duas penitenciárias em Minas Gerais. Foi realizada a prova tuberculínica nos indivíduos que aceitaram participar do estudo. Resultados: Foram selecionados 1.120 indivíduos para a pesquisa. A prevalência da ILTB foi de 25,2%. Na análise multivariada, a ILTB esteve associada com relato de contato com caso de tuberculose ativa dentro da penitenciária (OR ajustada = 1,51; IC95%: 1,05-2,18) e uso de drogas inaláveis (OR ajustada = 1,48; IC95%: 1,03-2,13). Foram identificados 131 pacientes sintomáticos respiratórios (11,7%). O teste anti-HIV foi realizado em 940 (83,9%) dos participantes, sendo positivo em 5 indivíduos (0,5%). Dois casos de tuberculose ativa foram identificados no período do estudo. Conclusões: A prevalência de ILTB dentro das penitenciárias estudadas foi alta. Além disso, a ILTB estava associada ao relato de contato com casos de tuberculose e ao uso de drogas inaláveis. Nossos achados demonstram que é necessária a melhoria das condições de encarceramento e a utilização de outras estratégias, como a triagem por radiografia de tórax, para a descoberta de casos de tuberculose e redução da infecção pelo M. tuberculosis no sistema penitenciário.

Challenging Mycobacterium tuberculosi s dormancy mechanisms and their immunodiagnostic potential

ABSTRACT Mycobacterium tuberculosis is the etiologic agent of tuberculosis, one of the world's greatest cause of morbidity and mortality due to infectious disease. Many evolutionary mechanisms have contributed to its high level of adaptation as a host pathogen. Prior to become dormant, a group of about 50 genes related to metabolic changes are transcribed by the DosR regulon, one of the most complex and important systems of host-pathogen interaction. This genetic mechanism allows the mycobacteria to persist during long time periods, establishing the so-called latent infection. Even in the presence of a competent immune response, the host cannot eliminate the pathogen, only managing to keep it surrounded by an unfavorable microenvironment for its growth. However, conditions such as immunosuppression may reestablish optimal conditions for bacterial growth, culminating in the onset of active disease. The interactions between the pathogen and its host are still not completely elucidated. Nonetheless, many studies are being carried out in order to clarify this complex relationship, thus creating new possibilities for patient approach and laboratory screening.

Dormancy models for Mycobacterium tuberculosis: A minireview

Dormancy models for Mycobacterium tuberculosis play important roles in understanding various aspects of tuberculosis pathogenesis and in the testing of novel therapeutic regimens. By simulating the latent tuberculosis infection, in which the bacteria exist in a non-replicative state, the models demonstrate reduced susceptibility to antimycobacterial agents. This minireview outlines the models available for simulating latent tuberculosis both in vitro and in several animal species. Additionally, this minireview discusses the advantages and disadvantages of these models for investigating the bacterial subpopulations and susceptibilities to sterilization by various antituberculosis drugs.

Suppression of Eis and expression of Wag31 and GroES in Mycobacterium tuberculosis cytosol under anaerobic culture conditions.

A major impediment in chemotherapy of Tuberculosis (TB) is the persistence of M. tuberculosis in a latent or dormant state, possibly perpetuated by paucity of oxygen within the lung granuloma. Proteome analysis of the anaerobically persisting microbe could therefore provide novel targets for drugs against latent TB infection (LTBI). An Indian clinical isolate of M. tuberculosis was cultured under aerobic and anaerobic conditions following Wayne’s hypoxia model and its cytosolic proteins were resolved by two-dimensional gel electrophoresis (2DE). Peptide mass fingerprinting of 32 differentially expressed spots using MALDI TOF-TOF MS-MS resulted in identification of 23 proteins. Under the anaerobic culture conditions, expression of 12 of these proteins was highly suppressed (>2 fold reduction in spot volumes), with 4 of them (GrpE, CanB, MoxR1 and Eis) appearing as completely suppressed since corresponding spots were not detectable in the anaerobic sample. On the other hand, 4 proteins were highly expressed, with two of them (Wag31 and GroES) being uniquely expressed under anaerobic conditions. Suppression of Eis could make the anaerobically persisting bacilli susceptible to the aminoglycoside antibiotics which are known to be acetylated and inactivated by Eis. Although all 4 over-expressed proteins can be considered as putative drug targets for LTBI, Wag31 appears particularly interesting in view of its role in the cell wall biogenesis.

Tuberculosis and latent tuberculosis in prison inmates / Tuberculose e tuberculose latente na população prisional / Tuberculosis y tuberculosis latente en la población carcelaria

OBJECTIVE: To estimate the prevalences of tuberculosis and latent tuberculosis in inmates. METHODS: Observational study was carried out with inmates of a prison and a jail in the State of São Paulo, Southeastern Brazil, between March and December of 2008. Questionnaires were used to collect sociodemographic and epidemiological data. Tuberculin skin testing was administered (PPD-RT23-2TU/0.1 mL), and the following laboratory tests were also performed: sputum smear examination, sputum culture, identification of strains isolated and drug susceptibility testing. The variables were compared using Pearson's chi-square (Χ2) association test, Fisher's exact test and the proportion test. RESULTS: Of the 2,435 inmates interviewed, 2,237 (91.9 percent) agreed to submit to tuberculin skin testing and of these, 73.0 percent had positive reactions. The prevalence of tuberculosis was 830.6 per 100,000 inmates. The coefficients of prevalence were 1,029.5/100,000 for inmates of the prison and 525.7/100,000 for inmates of the jail. The sociodemographic characteristics of the inmates in the two groups studied were similar; most of the inmates were young and single with little schooling. The epidemiological characteristics differed between the prison units, with the number of cases of previous tuberculosis and of previous contact with the disease greater in the prison and coughing, expectoration and smoking more common in the jail. Among the 20 Mycobacterium tuberculosis strains identified, 95.0 percent were sensitive to anti-tuberculosis drugs, and 5.0 percent were resistant to streptomycin. CONCLUSIONS: The prevalences of tuberculosis and latent tuberculosis were higher in the incarcerated population than in the general population, and they were also higher in the prison than in the jail.

OBJETIVO: Estimar a prevalência da tuberculose e tuberculose latente em detentos. MÉTODOS: Estudo observacional foi realizado com detentos de uma penitenciária e de um centro de detenção provisória do Estado de São Paulo, SP, entre março e dezembro de 2008. Questionários foram utilizados para a coleta de dados sociodemográficos e epidemiológicos. O teste tuberculínico foi aplicado (PPD-RT23-2UT/0,1ml) e os seguintes exames laboratoriais foram realizados: baciloscopia de escarro, cultura de escarro, identificação das cepas isoladas e teste de sensibilidade às drogas antituberculose. As variáveis foram comparadas utilizando-se o teste de associação qui-quadrado de Person (Χ2), teste exato de Fisher e teste das proporções. RESULTADOS: Dos 2.435 detentos entrevistados, 2.237 (91,9 por cento) concordaram em submeter-se ao teste tuberculínico e destes, 73,0 por cento foram reatores. O coeficiente de prevalência da tuberculose foi de 830,6 por 100.000 detentos. Os coeficientes de prevalência foram de 1.029,5/100.000 detentos na penitenciária e de 525,7/100.000 detentos no centro de detenção provisória. As características sociodemográficas dos detentos nos dois grupos estudados foram semelhantes; a maioria dos detentos era jovem e solteiro com baixa escolaridade. As características epidemiológicas diferiram entre as unidades prisionais com o número de casos de tuberculose no passado e de contato prévio com doente maior na penitenciária e tosse, expectoração e hábito de fumar mais comum no centro de detenção. Entre as 20 cepas de Mycobacterium tuberculosis identificadas, 95,0 por cento foram sensíveis às drogas antituberculose e 5,0 por cento foram resistentes à estreptomicina. CONCLUSÕES: As prevalências da tuberculose e da tuberculose latente foram maiores na população carcerária do que na população geral; e também maiores na penitenciária do que no centro de detenção provisória.

OBJETIVO: Estimar la prevalencia de la tuberculosis y tuberculosis latente en detenidos. MÉTODOS: Estudio observacional realizado de marzo a diciembre de 200 con 4.435 detenidos de una penitenciaria y de un centro de detención provisional del Estado de Sao Paulo, sureste de Brasil, entre marzo y diciembre 2008. Cuestionarios fueron utilizados para colecta de datos sociodemográficos y epidemiológicos. Prueba tuberculina fue aplicada (PPD-RT23-2UT/0,1ml), así como los exámenes de laboratorio: baciloscopia de esputo, cultivo de esputo, identificación y prueba de sensibilidad a las drogas antituberculosis. Las variables fueron comparadas utilizándose la prueba de chi-cuadrado de Pearson, prueba exacta de Fisher y la prueba de las proporciones. RESULTADOS: De los 2.435 detenidos entrevistados, 2.237 (91,9 por ciento) concordaron a se someter a la prueba tuberculina y de estos, 73,0 por ciento reaccionaron. El coeficiente de incidencia de la tuberculosis fue de 830,6 por 100.000 detenidos. Los coeficientes de incidencia fueron de 1.029,5/100.000 detenidos en la penitenciaria y de 525,7/100.000 detenidos en el centro de detención provisional. Las características sociodemográficas de los detenidos de los dos grupos estudiados fueron semejantes; la mayoría de los detenidos era joven y soltero con baja escolaridad. Las características epidemiológicas se diferenciaron entre las unidades prisonales, con mayor número de casos de tuberculosis en el pasado y de contacto previo con enfermo en la penitenciaria; y mayor número de tos, expectoración y hábito de fumar en el centro de detención. Entre las 20 cepas de Mycobacterium tuberculosis identificadas, 95,0 por ciento fueron sensibles a las drogas antituberculosis y 5,0 por ciento fueron resistentes a la estreptomicina. CONCLUSIONES: Las prevalencias de la tuberculosis y de tuberculosis latente fueron mayores en la población carcelaria que en la población general; y mayores en la penitenciaria que en el centro de detención provisional.

Tuberculosis: una dinámica continua entre el pasado y el presente, para imaginar el futuro / Tuberculosis: steady dynamics between past and present to imagine the future

Progress in understanding the biological processes that allow Mycobacterium tuberculosis to be a successful parasite have accelerated in the last twenty years. This progress has been stimulated by the return of tuberculosis (TB) as an important disease in industrialized countries, by its increase in emergent nations in the tail of population increases and poverty and by the spread of multiple drug resistant (MDR) and extensively drug resistant (XDR) M. tuberculosis as a result of treatment failures. Progress on M. tuberculosis biology has also been fueled by advances in microbiology and molecular biology, including molecular genetics, genomics, proteomics and in vitro and in vivo models of infection. The study of latency or dormancy, a phenomenon central to understanding the persistence of M. tuberculosis and the development of TB in individuals, its spread in human populations and the emergence of antibiotic-resistant/tolerant organisms, has been preferred targets for investigators in this area. In this manner, factors that trigger M. tuberculosis latency (e. g, hypoxia, nutrient starvation, NO exposure) have been characterized and the metabolic shifts to host lipid utilization, tolerance to antimicrobials and resistance to host immune mechanisms involved in latency have been determined. Similarly, genetic changes and the resulting antimicrobial mechanisms mediating the MDR and XDR states have been characterized and potential new vaccines that avoid reactivation from latency and infection are being developed. Despite this progress, and given the fact that effective anti tuberculosis therapy was developed and first introduced clinically at the end of the 1940s, there are now more cases of latent and active TB worldwide than ever before. This reinforces the concept of TB as a bacterial disease with strong social and economical! determinants which are presently stimulating increased transmission in many human groups, undermining diagnostics, treatment and prevention. It suggests that in a scenario of global economical crisis the struggle against TB will be weakened, unless efforts are included to alleviate poverty, decrease economic inequality, improve public health and allow democracy and political organization.

Health care workers humoral immune response against GLcB, MPT51 and HSPX from Mycobacterium tuberculosis

Tuberculosis (TB) is one of the oldest human infectious diseases and one third of the world's population is latently infected. Brazil is an endemic area for TB. One of the most important challenges in TB control is the identification of latently infected individuals. Health Care Workers (HCW) are at high risk of being infected with Mycobacterium tuberculosis and even to become TB latently infected. The aim of this study was to increase knowledge about humoral immune response in TB latently infected individuals. HCW were classified according to their tuberculin skin test (TST), as positive or negative. The antibody response to GLcB, MPT51 and HSPX from Mycobacterium tuberculosis was evaluated. TST negative HCW constituted the majority of those who showed a humoral immune response. Antibody levels varied according to antigen characteristics, TST and BCG status. We suggest that possibly the presence of those antibodies could have a function in the protective immune response against Mycobacterium tuberculosis.

Desempenho da técnica nested PCR na detecção específica do complexo Mycobacterium tuberculosis em amostras sanguíneas de pacientes pediátricos / Performance of nested PCR in the specific detection of Mycobacterium tuberculosis complex in blood samples of pediatric patients

Objetivo: Avaliar o desempenho da técnica nested PCR (nPCR) para detectar o complexo Mycobacterium tuberculosis em amostras de sangue de pacientes com suspeita de TB para sua possível utilização como uma ferramenta auxiliar no diagnóstico laboratorial da doença em crianças. Métodos: Detecção do complexo M. tuberculosis em amostras de sangue usando como alvo a sequência de inserção IS6110 do DNA genômico do bacilo. Foram avaliados 120 pacientes, menores de 15 anos de idade, de ambos os sexos, provenientes de hospitais públicos do Recife (PE), no período entre janeiro de 2003 e agosto de 2005. O diagnóstico de TB foi realizado pelo médico assistente do serviço de saúde de acordo com os critérios da Sociedade Torácica Americana. A nPCR amplificou um fragmento de 123 pb com oligonucleotídeos externos (IS1/IS2) e, na reação subsequente, com oligonucleotídeos internos (IS3/IS4), gerando um amplicon de 81 pb. Resultados: A TB ativa ou latente esteve presente em 65 pacientes, foi descartada em 28 suspeitos e 27 não tinham a doença (controles). A sensibilidade da nPCR foi de 26,15%, sendo significativamente maior na forma extrapulmonar (55,56%) em relação à pulmonar (18,18%), e a especificidade foi de 92,73%. Conclusões: Diante das dificuldades diagnósticas da TB infantil e do baixo número de casos estudados,a nPCR em sangue demonstrou ser uma técnica rápida e específica, mas com baixa sensibilidade. Para saber a suareal utilidade no diagnóstico de formas paucibacilares, sobretudo as extrapulmonares, novas pesquisas devem ser desenvolvidas com uma casuística maior de crianças e com outros espécimes biológicos além do sangue.

Objective: To evaluate the performance of nested PCR (nPCR) in detecting the Mycobacterium tuberculosis complex in blood samples of patients suspected of having TB, in order to determine its potential for use as an auxiliary tool in the laboratory diagnosis of TB in children. Methods: Detection of the M. tuberculosis complex in blood samples using as a target the insertion sequence IS6110 of the genomic DNA of the bacillus. Blood samples of 120 patients were evaluated. All of the patients were under 15 years of age at the time of their treatment at public hospitals in the city of Recife, Brazil (between January of 2003 and August of 2005). Attending physicians at the hospitals diagnosed TB based on the criteria recommended by the American Thoracic Society. The nPCRamplified a 123-bp fragment with outer oligonucleotides (IS1/IS2) and, in the subsequent reaction, using inner oligonucleotides (IS3/IS4), generating an 81-bp amplicon. Results: Active or latent TB was found in 65 patients,TB was ruled out in 28 suspected cases, and 27 patients were TB-free (controls). The sensitivity of nPCR was26.15% and was significantly higher for the extrapulmonary form of the disease (55.56%) than for the pulmonary form (18.18%). The specificity was 92.73%. Conclusions: Despite the difficulties in diagnosing TB in children and the low number of cases evaluated in the present study, nPCR in blood samples proved to be a rapid and specifictechnique, albeit one with low sensitivity. In order to establish its true usefulness in the diagnosis of paucibacillary forms, especially extrapulmonary TB, further studies need to be carried out with a larger sample of children and analyzing biological specimens other than blood.