Introduction: Despite management advances worldwide, tuberculosis still remains a serious uncontrolled disease. The absence of either a ‘gold’ standard diagnostic test, or a conventional rapid ‘reference’ laboratory test for asymptomatic Mycobacterium tuberculosis (MTB) carriers complicates disease control. Through mandatory screening of high-risk groups, early diagnosis of latent tuberculosis infection (LTBI) cases allows recognition and better control of the tuberculosis pandemic. Materials and Methods: The current tuberculosis screening guidelines as recommended by the World Health Organization, chest X-ray and tuberculin skin test were assessed and revealed rises in TB morbidity and fatality trends in the Kuwait population (low incidence country). In order to evaluate options for LTBI diagnosis, the current work implemented a 4-month prospective, observational, repeated-measure and randomly implemented survey on 180 new immigrants to Kuwait using a structured risk factor questionnaire whilst, simultaneously evaluating the performance of the two standard diagnostics (chest X-ray and tuberculin skin test) with the new biomarker interferon gamma release assays (T-SPOT .TB test and QuantiFERON Gold In-Tube test (QNF-GIT)); which detect the release of interferon gamma (INF-γ) released from sensitization to specific MTB antigens. Results: Associations between various epidemiological risk factors - such as socio-demographic status, smoking and environmental exposure-contact - were associated in the laboratory diagnosed LTBI participants. Positive identification of LTBI prevalence detected by two radiologists was 10.1% having ‘moderate’ inter-reader agreement (Kappa = 0.505), compared to no positives being detected by three pulmonologists. TST results were negative (less than 10-mm ‘cut-off’) even in the 86.1% Bacillus Calmette-Guérin vaccinated expatriates. Estimated LTBI using QNFGIT was 28.3% compared to 41.1% positive T-SPOT .TB test. Both interferon gamma assays revealed concordant ‘abnormal’ results in 26.1% with ‘good’ agreement (kappa = 0.627). Conclusion: Detection of latent tuberculosis infection can be facilitated by introducing evidence-based diagnostic classification depending on history taking of epidemiological-related risk factors and chest X-ray plus either interferon gamma assays.

Background: Migrant farmworkers are among the highest-risk populations for latent TB infection (LTBI) in the United States with numerous barriers to healthcare access and increased vulnerability to infectious diseases. LTBI is usually diagnosed on the border using the tuberculin skin test (TST). QuantiFERON-TB Gold In-Tube (QFT-GIT) also measures immune response against specific Mycobacterium tuberculosis antigens. The objective of this study is to assess the comparability of TST and QFT-GIT to detect LTBI among migrant farmworkers on the border, as well as to examine the effects of various demographic and clinical factors on test positivity. Methods: Participants were recruited using mobile clinics on the San Luis US-Mexico border and tested with QFT-GIT and TST. Demographic profiles and clinical histories were collected. Kappa coefficients assessed agreement between TST and QFT-GIT using various assay cutoffs. Logistic regression examined factors associated with positive TST or QFT-GIT results. Results: Of 109 participants, 59 of 108 (55 %) were either TST (24/71, 34 %) or QFT-GIT (52/106, 50 %) positive. Concordance between TST and QFT-GIT was fair (71 % agreement,kappa= 0.38, 95 % CI: 0.15, 0.61). Factors associated with LTBI positivity included smoking (OR = 1.26, 95 % CI-1.01-1.58) and diabetes/high blood sugar (OR = 0.70, 95 % CI = 0.51-0.98). Discussion: Test concordance between the two tests was fair, with numerous discordant results observed. Greater proportion of positives detected using QFT-GIT may help avoid LTBI under-diagnosis. Assessment of LTBI status on the border provides evidence whether QFT-GIT should replace the TST in routine practice, as well as identifies risk factors for LTBI among migrant populations.

Preventative interventions often demand that resources be consumed in the present in exchange for future benefits. Understanding these trade-offs, in a context of resource constraints, is essential for policy makers. Cost-effectiveness analysis is one tool to inform decision-making. Targeted testing and treatment (TTT) for latent tuberculosis infection (LTBI) consists in identifying people at high risk for LTBI for preventive treatment to decrease the risk that they will develop active tuberculosis disease (ATBD). The state of Tennessee began conducting TTT statewide in 2001. This study uses a decision tree to evaluate the cost and outcomes of TTT for LTBI in Tennessee, compared to passive ATBD case finding (PACF). Key event probabilities were obtained from the Tennessee TTT program and from the literature. Outcomes are measured in terms of Quality Adjusted Life Years (QALY). The cost-effectiveness threshold was set at $100,000/QALY saved. One-way sensitivity analyses around factors related to study design (exclusion of patient costs, secondary transmission, discount rate and analytical horizon), the program’s environment (prevalence of LTBI and drug resistance, ATBD treatment costs) and program performance (program maturity, treatment initiation and completion rate, testing in low-risk group, test characteristics, screening costs) were conducted, as was probabilistic sensitivity analysis (PSA) which takes into account the uncertainty in multiple parameters simultaneously. The base case, with a 25-year time horizon and 3% discount rate, shows that TTT prevents 47 ATBD cases, and saves 31 QALYs per 100,000 patients screened for LTBI at a societal cost of $12,579 (2011 US$) per QALY saved. Sensitivity analyses identified value thresholds that would trigger a change in preferred policy. PSA shows that the likelihood that TTT would be cost-effective is low. Decision makers interested in implementing TTT should carefully assess the characteristics of the local TB epidemic and expected program performance to determine whether TTT is preferable over PACF from a cost-effectiveness viewpoint.

Preventative interventions often demand that resources be consumed in the present in exchange for future benefits. Cost-effectiveness analysis is a tool to understand these trade-offs, and inform decision-making under resource constraints. Targeted testing and treatment (TTT) for latent tuberculosis infection (LTBI) consists in identifying people at high risk for LTBI for preventive treatment to decrease the risk of active tuberculosis disease (ATBD). The state of Tennessee began conducting TTT statewide in 2001. This study uses a decision tree to evaluate the cost and outcomes of TTT for LTBI in Tennessee, compared to passive ATBD case finding (PACF). Key probabilities were obtained from the Tennessee TTT program and the literature. Outcomes are measured in terms of Quality Adjusted Life Years (QALY). The cost-effectiveness threshold was $100,000/QALY saved. One-way sensitivity analyses around factors related to study design, the program’s environment, and program performance were conducted, as was probabilistic sensitivity analysis (PSA) which takes into account the uncertainty in multiple parameters simultaneously. The base case, with a 25-year analytic horizon and 3% discount rate, shows that TTT prevents 47 ATBD cases, and saves 31 QALYs per 100,000 patients screened at a societal cost of $12,579 per QALY saved. Sensitivity analyses identified value thresholds that would trigger a change in preferred policy. PSA shows that the likelihood that TTT would be cost-effective is low. Decision makers should carefully assess the characteristics of the local TB epidemic and expected program performance to determine whether TTT is preferable over PACF from a cost-effectiveness viewpoint.

Submitted by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2015-10-22T13:46:44Z No. of bitstreams: 1 Jessica Dias Petrilli.Avaliação ... 2015.pdf: 2014197 bytes, checksum: 11dd7ed8b03eff8645c6f34b778cc32e (MD5) / Approved for entry into archive by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2015-10-26T11:29:00Z (GMT) No. of bitstreams: 1 Jessica Dias Petrilli.Avaliação ... 2015.pdf: 2014197 bytes, checksum: 11dd7ed8b03eff8645c6f34b778cc32e (MD5) / Made available in DSpace on 2015-10-26T11:29:00Z (GMT). No. of bitstreams: 1 Jessica Dias Petrilli.Avaliação ... 2015.pdf: 2014197 bytes, checksum: 11dd7ed8b03eff8645c6f34b778cc32e (MD5) Previous issue date: 2015 / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Os macrófagos são componentes importantes da resposta imune inata contra o Mycobaterium tuberculosis (Mtb) e podem desempenhar um papel importante na patogênese da tuberculose (TB). Macrófagos são derivados dos monócitos, os quais são classificados em subpopulações a partir da expressão da molécula de superfície CD14 e CD16. São denominados de clássicos, intermediários e não clássicos, e possuem diferenças funcionais e fenotípicas. Os fatores que levam ao desenvolvimento de TB ativa ainda não são claros. Um desequilíbrio entre subpopulações de monócitos circulantes pode estar envolvido na imunopatogênese da TB, uma vez que macrófagos são células importantes da resposta imune inicial da doença. Assim, neste estudo avaliou-se os subgrupos de monócitos em pacientes com TB ativa e latente (TBL). Voluntários com TB ativa, TBL e indivíduos saudáveis foram recrutados para avaliação de frequência, níveis de ativação e produção de citocinas dos subgrupos de monócitos circulantes e após a estimulação antigênica por citometria de fluxo. Nossos resultados não demonstraram diferenças significativas nas frequências, níveis de ativação e produções de citocinas das subpopulações de monócitos entre os grupos estudados. No entanto, pacientes com TB ativa tiveram um aumento na frequência dos monócitos clássicos ativados após estimulação antigênica comparados com os controles saudáveis. Não observou-se uma expansão das subpopulações CD16+ em pacientes TB. Por outro lado, se observou uma expansão dos monócitos CD16- e maior ativação dessa subpopulação após estimulação antigênica em indivíduos TB e TBL. Diante disso, os monócitos clássicos parecem desempenhar algum papel na infecção da TB, uma vez que esta subpopulação se expande e apresenta-se mais ativada após estimulação antigênica principalmente em resposta a Mce1A. Entretanto, esta expansão de monócitos clássicos na TB ainda precisa ser avaliada / Macrophages are important components of the innate immune response against Mycobacterium tuberculosis (Mtb) and may play an important role in the pathogenesis of tuberculosis (TB). Macrophages are derived from monocytes, which are classified into subpopulations from the expression of CD14 and CD16 surface molecule. They are denominated classics, intermediate and non-classical, and have functional and phenotypic differences. The factors that lead to the development of active tuberculosis are not clear yet. However, an imbalance between subpopulations of monocytes may be involved in the immunopathogenesis of TB, since macrophages are important cells in the initial immune responses of the disease. In this study we evaluated the monocyte subsets in patients with active and latent TB (ILTB). Volunteers with active TB, ILTB and healthy subjects were recruited to evaluate the frequency, levels of activation and cytokine production of blood monocytes subsets circulating and after the antigenic stimulation by flow cytometry. Our results did not show significant differences in the frequency, activation levels and cytokine production of monocytes subsets between studies groups. However, patients with active TB have an increased of frequency and activated levels of classical monocytes after antigenic stimulation compared to healthy controls. An expansion of CD16+ in monocytes subsets of TB patient was not observed. Moreover, it was observed an expansion and increased activation of CD16- monocytes after antigenic stimulation in individuals TB and LTB. Thus, the classical monocytes seems to play a role in TB infection, since this subpopulation expands and appears more active primarily after antigenic stimulation in response to Mce1A. However, this expansion of classical monocytes in TB still needs to be evaluated.

Thesis (MTech (Biomedical Technology))--Cape Peninsula University of Technology, 2007 / Reinfection is an important mechanism leading to recurrent tuberculosis. Recently, molecular epidemiological studies have shown that in high incidence settings, recurrent tuberculosis may occur through reinfection. Animal model experiments have shown that a reinfecting mycobacterial strain is specifically targeted to existing granulomas and that these structures are more dynamic than was previously thought. In this study we hypothesised that primary infection with M. tuberculosis may reprogramme human macrophages thereby preventing or facilitating reinfection with a secondary mycobacterial strain. Two antibiotic-resistant M. tuberculosis H37Rv variants were generated by electrotransformation of marked plasmids, designated KanRand HygR . A THP1 human macrophage cell line was infected and reinfected with different combinations of these marked strains as well as a hypervirulent M. tuberculosis Beijing strain. Mycobacterial growth has been assessed by colony forming unit enumeration and confirmed with polymerase chain reaction (PCR) analysis. In vitro growth curves of wild-type and differentially marked M. tuberculosis H37Rv Kan Rand HygR strains were compared in the BACTECTM mycobacterial growth indicator tube (MGITTM) system in parallel with conventional liquid culturing. In vitro liquid culture growth curves of hypervirulent clinical Beijing strain isolates were also compared to M. tuberculosis H37Rv growth curves. Through this it was established that there was no fitness cost as result of plasmid integration and that these strains of varying virulence had similar growth curves. Competitive dynamics within THP1 human macrophage cells were then assessed and have shown that there were no significant differences in growth patterns between primary and secondary infecting strains during THP1 cell reinfection. The findings of this study answered fundamental questions regarding reinfection of mycobacterial strains. It was established here that human macrophages can indeed be reinfected with a second virulent mycobacterial strain.

Made available in DSpace on 2014-07-29T15:04:41Z (GMT). No. of bitstreams: 1 dissertacao lilian.pdf: 281825 bytes, checksum: 488c9e5d58cb1a521b28a8592ee6de50 (MD5) Previous issue date: 2006-02-23 / According to the World Health Organization (WHO), an hundred million of individuals are infected by M. tuberculosis, annually. Health care workers play an important role to control of tuberculosis, but they are also at high risk for this infection. Then, the objectives of the present study were to evaluate the prevalence of M tuberculosis infection in nursing professionals from the Tropical Diseases Hospital in Goiânia City, State of Goiás, to analyze the factors associated to tuberculin skin test (TST) positivity and to determine the TB infection incidence density in susceptible professionals Initially, the prevalence and factors associated to TST were investigated in 128 eligible individuals. Further, susceptible professionals (n=32) were followed up during three years (2001-2004) to detect TST conversion. Of the total individuals investigated, 69.5% (IC 95%: 60.7-77.2) were positive to TST. Two occupational factors were independently associated to skin test positivity: duration of profissional activity longer than 5 years (Adjustd OR = 6.3; 95% CI: 1.5-26.2) and occupational contact with a person with pulmonary TB ≤ 2 years (Adjusted OR = 12.2; 95% CI: 1.2-106.3). Seven profissionals showed tuberculinic conversion during the three years of follow up, and an incidence density of 11.5 new conversions to 100 persons-year was detected. All of them had taken care of patients during the period of the study. Two individuals developed tuberculosis disease. The data of this study ratify the high risk of tuberculosis in nursing team, and highlight the importance of this infection as an occupational disease to nursing professionals of our region. / De acordo com a Organização Mundial de Saúde (OMS), cem milhões de pessoas são infectadas pelo M. tuberculosis, a cada ano. Os profissionais de saúde são importantes para o controle da tuberculose, mas também um grupo de risco elevado para esta infecção. Assim, o presente estudo teve como objetivos avaliar a prevalência da infecção causada pelo M. tuberculosis em profissionais de enfermagem de uma instituição especializada em doenças infecciosas, em Goiânia Go, analisar os fatores associados à positividade à prova tuberculínica nesta população e determinar a densidade de incidência da infecção pelo M. tuberculosis, nos profissionais susceptíveis. Inicialmente, verificou-se a prevalência e os fatores associados à positividade à PT. A seguir, os profissionais suscetíveis à infecção (n=32) foram acompanhados, por três anos (2001-2004), para detecção de conversão tuberculínica. Do total de profissionais investigados, 69,5% (IC 95%: 60,7- 77,2) foram positivos à PT. Dois fatores ocupacionais foram independentemente associados à positividade à PT: tempo de atividade profissional > 5 anos (OR ajustado = 6,3; IC 95%: 1,5-26,2) e último contato laboral com alguém com TB ≤ 2 anos (OR ajustado = 12,2; IC95%: 1,2-106,3). Sete profissionais apresentaram viragem tuberculínica, resultando em uma densidade de incidência de 11,5 novas conversões por 100 pessoas/ano. Todos desenvolviam atividades assistenciais, durante o período do estudo. Duas profissionais desenvolveram tuberculose doença. Os resultados, deste estudo, ratificam o elevado risco de tuberculose nos profissionais de enfermagem, e evidenciam a importância desta infecção como doença ocupacional para equipe de enfermagem de nossa região.

Latent tuberculosis infection (LTBI) is a global health issue that affects approximately one quarter of the world’s population. It refers to a state of persistent immune response to Mycobacterium tuberculosis without clinical evidence of active tuberculosis (TB). Latent tuberculosis infected individuals are asymptomatic and not contagious to others, however 5-15% of all infected individuals are at risk of developing active tuberculosis and become contagious, severely ill, or worse, die from active TB. There are identified risk groups that are targeted for identification, diagnosis and treatment of latent tuberculosis infection. These are human immunodeficiency virus (HIV) patients, children and adolescents, household or close contacts of active TB cases, migrants, refugees, prisoners and health care workers. The standard treatment used for treating LTBI is the isoniazid monotherapy. It has a high proven efficacy rate but is linked to poor acceptance and low completion rates, basically due to its long treatment duration and poor tolerability. A newer treatment regimen is the rifapentine plus isoniazid combination therapy. It is an effective regimen against LTBI and has a shorter treatment duration. The aim of this literature study was to evaluate the efficacy of rifapentine plus isoniazid combination therapy compared with the isoniazid monotherapy as treatment of latent tuberculosis infection. This thesis was based on five randomized clinical trials collected from PubMed database. The studies should have entailed an efficacy comparison between isoniazid monotherapy and rifapentine plus isoniazid combination therapy for the treatment of patients with latent tuberculosis. The studies showed lower rates of active TB and death in the rifapentine plus isoniazid combination group in comparison with the isoniazid monotherapy. The studies also proved that rifapentine plus isoniazid combination therapy was noninferior to the standard isoniazid monotherapy. The completion rates were significantly higher in the combination therapy arm. The safety profile between the two treatment regimens was similar, but with an increased hepatotoxicity rates in the isoniazid-only arm. The rifapentine plus isoniazid combination therapy is as efficacious as the isoniazid monotherapy. This shorter regimen could be used as first hand therapy as well for latent tuberculosis patients with high-risk of developing active TB as it has shown good tolerability and higher completion rates that is important to successfully treat LTBI and help eliminate TB worldwide. / Latent tuberkulos är ett globalt hälsoproblem som drabbar ungefär en fjärdedel av världens befolkning. Den definieras som ett tillstånd av immunreaktion mot Mycobacterium tuberculosis utan kliniska tecken på aktiv tuberkulos (TB). De infekterade individerna är asymtomatiska och inte smittsamma för andra, men 5–15% av alla infekterade individer riskerar att utveckla aktiv tuberkulos och bli smittsamma, bli allvarligt sjuka, eller värre, dö av aktiv tuberkulos. Personer med latent tuberkulos som tillhör riskgrupperna prioriteras för identifiering, diagnos och behandling av latent tuberkulos. Dessa riskgrupper är humant immunbristvirus (HIV)-patienter, barn och ungdomar, nära kontakter till personer med aktiva TB-fall, migranter, flyktingar, fångar och vårdpersonal. Standardbehandlingen mot latent tuberkulos är isoniazid monoterapi. Den har en högt beprövad effektivitetsgrad men är kopplad till dålig acceptans och låga kompletteringsgrader, på grund av framförallt den långa behandlingstiden och dålig tolerans. En nyare form av behandling är rifapentin kombinerat med isoniazid. Den är en effektiv behandling mot latent tuberkulos med en kortare behandlingstid. Syftet med denna litteraturstudie var att utvärdera effekten av kombinationsterapi med rifapentin och isoniazid jämfört med isoniazid monoterapi för behandling av latent tuberkulos. Detta examensarbete baserades på fem randomiserade kliniska prövningar hämtade från PubMed-databasen. Samtliga fem studier innefattade effektivitetsjämförelse mellan isoniazid monoterapi och kombinationsterapi med rifapentin och isoniazid vid behandling av patienter med latent tuberkulos. Alla fem studier undersöktes visade lägre frekvens av aktiv TB och dödlighet i kombinationsterapi med rifapentin och isoniazid jämfört med isoniazid monoterapi. Resultatet bevisade också icke-underlägsenhet för kombinationsterapin jämfört med isoniazid monoterapin. Kompletteringsgraden var signifikant högre i kombinationsterapin. Säkerhetsprofilen mellan de två terapin var likartad, men med en ökad hepatotoxicitet i isoniazid monoterapi gruppen. Kombinationsterapi med rifapentin och isoniazid är lika effektiv som isoniazid monoterapi. Denna kortare behandling kan också användas som förstahandsbehandling för latent tuberkulos patienter med hög risk att utveckla till aktiv tuberkulos eftersom den har visat god tolerabilitet och högre kompletteringsgrad som är viktigt för att framgångsrikt behandla latent tuberkulos och hjälpa till att eliminera TB över hela världen.

Hemerythrin-like protein Rv2633c is a small 18 kDa protein that is expressed in Mycobacterium tuberculosis (Mtb). Sequence analysis of Rv2633c predicts the presence of a hemerythrin-like domain, which binds dioxygen using a µ-oxo-bridge (Fe-O-Fe), rather than a heme group. Though it is noticeably upregulated during macrophage infection and during in vitro acidification, the role of Rv2633c in Mtb survival has yet to be elucidated. This project aims to characterize the function of Rv2633c by studying the in vitro response of the recombinant protein to conditions present in the macrophage lysosome, such as reduced oxygen levels or the presence of reactive oxygen species. UV-visible spectroscopy is used to observe these changes, as the spectrum shows a characteristic peak at 330 nm that likely corresponds to the diiron cofactor in its native state. Our results show this spectrum shifts in response to hydrogen peroxide addition, showing the proposed environmental conditions can affect the active site. Bioinformatics techniques, such as the 3D modeling program SWISS-MODEL, have been used to hypothesize possible structure and function. Determining the function of Rv2633c may help explain how Mtb so readily evades the human immune system to reside in the macrophage.

No description available.