RESUMO
Solar grade silicon (SoGSi) is a key material for the development of crystalline silicon photovoltaics (PV), which is expected to reach the tera-watt level in the next years and around 50TW in 2050. Upgraded metallurgical grade silicon (UMGSi) has already demonstrated to be a viable alternative to standard polysilicon in terms of cost and quality. This study presents the life cycle assessment (LCA) of UMG obtained by the FerroSolar process. Moreover, it shows the environmental impacts of PV modules and electricity generation based on this material. For this, an exhaustive review of the life cycle inventory (LCI) of PV value chain, from metallurgical grade silicon (MG-Si) down to electricity generation, has been carried out updating inputs for all processes. The Balance of System (BoS) has also been updated with current state of the art data for a fixed open ground large PV site (100 MWpk). Two different electricity mixes, with low and high carbon intensities, have been considered. The results reveal that for PV electricity generation using UMG-Si instead of polysilicon leads to an overall reduction of Climate change (CC) emissions of over 20%, along with an improvement of the Energy Payback Time (EPBT) of 25%, achieving significantly low values, 12 gCO2eq/kWhe and 0.52 years, respectively. Moreover, it is shown that UMG silicon feedstock is not the main contributor to the carbon and energy footprint of the produced electricity, leaving the first place to PV module manufacturing.
Assuntos
Silício , Energia Solar , Animais , Carbono , Eletricidade , Meio Ambiente , Estágios do Ciclo de VidaRESUMO
BACKGROUND: Postzygotic de novo mutations lead to the phenomenon of gene mosaicism. The 3 main types are called somatic, gonadal, and gonosomal mosaicism, which differ in terms of the body distribution of postzygotic mutations. Mosaicism has been reported occasionally in patients with primary immunodeficiency diseases (PIDs) since the early 1990s, but its real involvement has not been systematically addressed. OBJECTIVE: We sought to investigate the incidence of gene mosaicism in patients with PIDs. METHODS: The amplicon-based deep sequencing method was used in the 3 parts of the study that establish (1) the allele frequency of germline variants (n = 100), (2) the incidence of parental gonosomal mosaicism in families with PIDs with de novo mutations (n = 92), and (3) the incidence of mosaicism in families with PIDs with moderate-to-high suspicion of gene mosaicism (n = 36). Additional investigations evaluated body distribution of postzygotic mutations, their stability over time, and their characteristics. RESULTS: The range of allele frequency (44.1% to 55.6%) was established for germline variants. Those with minor allele frequencies of less than 44.1% were assumed to be postzygotic. Mosaicism was detected in 30 (23.4%) of 128 families with PIDs, with a variable minor allele frequency (0.8% to 40.5%). Parental gonosomal mosaicism was detected in 6 (6.5%) of 92 families with de novo mutations, and a high incidence of mosaicism (63.9%) was detected among families with moderate-to-high suspicion of gene mosaicism. In most analyzed cases mosaicism was found to be both uniformly distributed and stable over time. CONCLUSION: This study represents the largest performed to date to investigate mosaicism in patients with PIDs, revealing that it affects approximately 25% of enrolled families. Our results might have serious consequences regarding treatment and genetic counseling and reinforce the use of next-generation sequencing-based methods in the routine analyses of PIDs.
Assuntos
Alelos , Frequência do Gene , Síndromes de Imunodeficiência/genética , Mosaicismo , Família , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Síndromes de Imunodeficiência/imunologia , MasculinoRESUMO
OBJECTIVE: To summarize and compare the risks of malignancies accompanying biologic DMARDs (b-DMARDs) and tofacitinib in rheumatoid arthritis (RA) in randomized clinical trials (RCTs) and long-term extension studies (LTEs). METHODS: Articles in Medline, Embase, Cochrane Library, and the Web of Science dated from 2000 to February 2015. Selection criteria were as follows: (1) focus on RCTs or LTEs in RA; (2) treatment with b-DMARDs or tofacitinib; (3) data on malignancies; and (4) a minimum follow-up of 12 weeks. Data included publication details, study design, risk of bias, number and types of malignancies, and patient characteristics and treatments. DATA SYNTHESIS: Of 113 articles and one updated report that were meta-analyzed, overall malignancies in RCTs showed odds ratio (95% confidence intervals) of 1.01 (0.72, 1.42) for all TNF antagonists, 1.12 (0.33, 3.81) for abatacept, 0.54 (0.20, 1.50) for rituximab, 0.70 (0.20, 2.41) for tocilizumab, and 2.39 (0.50, 11.5) for tofacitinib. Network meta-analysis of overall malignancies showed odds ratio (95% predictive intervals) of 1.68 (0.48-5.92) for infliximab, 0.79 (0.44-1.40) for etanercept, 0.93 (0.43-2.03) for adalimumab, 0.87 (0.28-2.75) for certolizumab, 0.87 (0.39-1.95) for golimumab, 1.04 (0.32-3.32) for abatacept, 0.58 (0.21-1.56) for rituximab, 0.60 (0.16-2.28) for tocilizumab, and 1.15 (0.24-5.47) for tofacitinib. Marginal numerical differences in the incidence rate of solid and hematological malignancies and non-melanoma skin cancers appeared in LTEs. CONCLUSIONS: In RCTs, treatment of RA with b-DMARDs or tofacitinib does not increase the risk for malignancies. Generalizability of the differences in the rate of specific malignancies encountered in LTEs requires continuous pharmacovigilance of real-world patients.
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Antirreumáticos/efeitos adversos , Artrite Reumatoide/tratamento farmacológico , Produtos Biológicos/efeitos adversos , Neoplasias/induzido quimicamente , Piperidinas/efeitos adversos , Pirimidinas/efeitos adversos , Pirróis/efeitos adversos , Antirreumáticos/uso terapêutico , Produtos Biológicos/uso terapêutico , Humanos , Metanálise em Rede , Piperidinas/uso terapêutico , Pirimidinas/uso terapêutico , Pirróis/uso terapêutico , RiscoRESUMO
The objective of the study was to analyze the impact of TNF antagonists (TNFa) on the total cholesterol and triglycerides on ankylosing spondylitis (AS) and psoriatic arthritis (PsA). In this single-centre observational study of AS and PsA patients, differences in triglyceride and total cholesterol levels and frequency of hypertriglyceridemia and hypercholesterolemia at 3 and 6 months were analysed in patients treated and not treated with TNFa. General estimation equations and linear regression analysis were used to investigate associations between disease activity and lipid levels and to identify predictors of change. One hundred fifty-seven patients treated, and 157 not treated with TNFa, were included in the study. A transient increase in cholesterol level from baseline to 3 months in TNFa-treated patients was the only statistically significant effect (P < 0.001). Persistent percentages of hypertriglyceridemia and hypercholesterolemia from baseline were significantly higher in not treated than in TNFa-treated patients (P = 0.009 and P = 0.001, respectively). Inverse associations between changes in cholesterol level and Bath Ankylosing Spondylitis Disease Activity Index (P = 0.011) and CRP (P < 0.001), but not Disease Activity Score in 28 Joints (P = 0.095) were found in the whole group. In AS and PsA patients treated with TNFa, mild and transient changes in cholesterol but not in triglyceride levels were associated with changes in disease activity.
Assuntos
Artrite Psoriásica/tratamento farmacológico , Colesterol/sangue , Etanercepte/uso terapêutico , Espondilite Anquilosante/tratamento farmacológico , Fator de Necrose Tumoral alfa/antagonistas & inibidores , Adulto , Antirreumáticos/uso terapêutico , Artrite Psoriásica/sangue , Artrite Psoriásica/epidemiologia , Biomarcadores/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Índice de Gravidade de Doença , Espanha/epidemiologia , Espondilite Anquilosante/sangue , Espondilite Anquilosante/epidemiologia , Resultado do Tratamento , Triglicerídeos/sangueRESUMO
Blinded rechecking is a method proposed for external quality assurance (EQA) of auramine-stained acid-fast bacilli (AFB) smears using fluorescence microscopy (FM), however, this procedure is not well developed and slides fading over time could compromise its implementation. Since bleaching of fluorescent molecules involves temperature-dependent chemical reactions, it is likely that low temperatures could slow down this process. We stored auramine-stained slides under different environmental conditions, including -20°C, and examined them over time. The slides stored in all the environments faded. At -20°C, fading was not reduced in relation to room temperature. Restaining and re-examining smears after five months showed that the slides containing saliva and storage at -20°C were associated with failure in AFB reappearance. In conclusion, the practice of freezing slides until they are viewed should be discouraged as it has a negative effect on blinded rechecking by reducing reading concordance after restaining. Specimen quality should be considered when interpreting FM-EQA results.
Assuntos
Benzofenoneídio/efeitos da radiação , Corantes Fluorescentes/efeitos da radiação , Microscopia de Fluorescência/métodos , Fotodegradação , Garantia da Qualidade dos Cuidados de Saúde/métodos , Escarro/microbiologia , Coloração e Rotulagem/métodos , Tuberculose/diagnóstico , Argentina , Benzofenoneídio/análise , Criopreservação , Estudos de Viabilidade , Corantes Fluorescentes/análise , Humanos , Iluminação , Microscopia de Fluorescência/instrumentação , Variações Dependentes do Observador , Valor Preditivo dos Testes , Preservação Biológica/métodos , Reprodutibilidade dos Testes , Método Simples-Cego , TemperaturaRESUMO
OBJECTIVES: To assess the proportion of RA patients who discontinued biologics in world registries and health care databases and to identify causes and predictors of discontinuation. METHODS: Medline, Embase, Cochrane Library and Web of Science electronic databases and ACR and EULAR meeting abstracts were used. The selection of studies from world registries and health care databases including RA patients treated with biologics was independently performed. Data extracted from articles and abstracts were combined using a random effects model. Meta-analyses of percentages and hazard ratios were used to assess discontinuation. RESULTS: Ninety-eight studies with >200 000 patients from 11 242 articles and 119 abstracts met the inclusion criteria. Overall discontinuation rates of TNF inhibitors at 0.5, 1, 2, 3 and 4 years were 21, 27, 37, 44 and 52%, respectively. Discontinuation of etanercept was significantly lower at 3 and 4 years (35% and 41%, respectively) than infliximab and adalimumab (46% and 52%, respectively). Predictors of time to discontinuation were etanercept [hazard ratios (HRs) 0.58 and 0.77 versus infliximab and adalimumab, respectively), concomitant use of DMARDs (HR 0.77), disease duration (HR 1.01) and female sex (HR 1.18). Studies from registries conducted after 2005 and from countries with lower biologics access showed higher percentages of discontinuation. Relevant data on abatacept and tocilizumab were missing. CONCLUSION: In RA, treatment with etanercept has a lower percentage of discontinuation than infliximab and adalimumab. Concomitant use of DMARDs, disease duration before treatment with a biologic and female sex predict time to discontinuation.
Assuntos
Antirreumáticos/administração & dosagem , Artrite Reumatoide/tratamento farmacológico , Produtos Biológicos/administração & dosagem , Suspensão de Tratamento/estatística & dados numéricos , Adalimumab/administração & dosagem , Adalimumab/efeitos adversos , Antirreumáticos/efeitos adversos , Artrite Reumatoide/diagnóstico , Artrite Reumatoide/mortalidade , Produtos Biológicos/efeitos adversos , Etanercepte/administração & dosagem , Etanercepte/efeitos adversos , Feminino , Humanos , Infliximab/administração & dosagem , Infliximab/efeitos adversos , Masculino , Valor Preditivo dos Testes , Ensaios Clínicos Controlados Aleatórios como Assunto , Sistema de Registros , Medição de Risco , Taxa de SobrevidaRESUMO
OBJECTIVE: To identify predictors of response to tumor necrosis factor (TNF) antagonists in ankylosing spondylitis (AS) and psoriatic arthritis (PsA). METHODS: Systematic review and meta-analysis of clinical trials and observational studies based on a systematic search. Meta-analyses of similar observations were performed using random effects computing summary OR. Heterogeneity was tested using I(2), and risks of bias using funnel plots and the Egger test. Meta-regression was used to explore causes of heterogeneity. RESULTS: The electronic search captured 1340 references and 217 abstracts. 17 additional articles were identified after searching by hand. A total of 59 articles meet the purpose of the study and were reviewed. 37 articles (33 studies) included 6736 patients with AS and 23 articles (22 studies) included 4034 patients with PsA. 1 article included data on AS and PsA. Age (OR (95% CI) 0.91 (0.84 to 0.99), I(2)=84.1%), gender (1.57 (1.10 to 2.25), I(2)=0.0%), baseline BASDAI (1.31 (1.09 to 1.57), I(2)=0.0%), baseline BASFI (0.86 (0.79 to 0.93), I(2)=24.9%), baseline dichotomous C reactive protein (CRP) (2.14 (1.71 to 2.68), I(2)=22.3%) and human leucocyte antigen B27 (HLA-B27) (1.81 (1.35 to 2.42), I(2)=0.0%) predict BASDAI50 response in AS. No factor was identified as a source of heterogeneity. Only meta-analysis of baseline BASFI showed risk of publication bias (Egger test, p=0.004). Similar results were found for ASAS criteria response. No predictors of response were identified in PsA. CONCLUSIONS: Young age, male sex, high baseline BASDAI, low baseline BASFI, high baseline CRP and HLA-B27 predict better response to TNF antagonists in AS but not in PsA.
RESUMO
Psoriatic arthritis (PsA) is a chronic inflammatory disease of the joints that occurs in patients with psoriasis. The spectrum of PsA includes arthritis, dactylitis, enthesitis, axial involvement, and skin lesions. Non-biologic disease-modifying anti-rheumatic drugs (DMARDs) such as methotrexate and leflunomide, and biologic DMARDs such as tumor necrosis factor (TNF) antagonists and ustekinumab, have been used to treat PsA. Apremilast is a novel therapy that inhibits phosphodiesterase 4, increases intracellular cAMP levels, and modulates expression of inflammatory mediators in favor of anti-inflammatory activity. It decreases the pro-inflammatory cytokines TNF-α, IFN-γ, IL-17, and IL-23 and increases the anti-inflammatory cytokine IL-10 under certain conditions. One phase II and four phase III clinical trials as well as long-term extension studies showed significant and sustained clinical efficacy and an adequate safety profile for apremilast in patients with active psoriatic arthritis.
Assuntos
Antirreumáticos/uso terapêutico , Artrite Psoriásica/tratamento farmacológico , Inibidores da Fosfodiesterase 4/uso terapêutico , Talidomida/análogos & derivados , Artrite Psoriásica/imunologia , Artrite Psoriásica/patologia , Ensaios Clínicos Fase II como Assunto , Ensaios Clínicos Fase III como Assunto , Citocinas/imunologia , Humanos , Talidomida/uso terapêuticoRESUMO
OBJECTIVE: To analyze lipid changes in patients with rheumatoid arthritis (RA) and patients with spondyloarthritis (SpA) treated with biologic agents or tofacitinib in randomized clinical trials (RCTs). METHODS: A systematic literature search was performed, using the Medline, Embase, Cochrane Library, and Web of Knowledge databases. Meta-analyses were performed using random-effects models to assess changes in the percentage of patients with abnormal lipid values or in the mean percentage of increase in the cholesterol and triglycerides levels. RESULTS: Twenty-five of 4,527 identified articles met the inclusion criteria. Compared with RA patients treated with placebo, those treated with tocilizumab were more likely to have hypercholesterolemia (odds ratio [OR] 4.64; 95% confidence interval [95% CI] 2.71, 7.95 [P < 0.001]), increased levels of high-density lipoprotein (HDL) cholesterol (OR 2.25; 95% CI 1.14, 4.44 [P = 0.020]), and increased levels of low-density lipoprotein (LDL) cholesterol (OR 4.80; 95% CI 3.27, 7.05 [P < 0.001]); this was not observed in patients treated with tumor necrosis factor (TNF) antagonists (OR 1.54; 95% CI 0.90, 2.66 [P = 0.119]) or tofacitinib (OR 3.4; 95% CI 0.62, 18.55 [P = 0.158]). Among patients receiving tofacitinib 5 mg twice daily, the mean percentage of increases in the HDL cholesterol level (weighted mean difference [WMD] 13.00 mg/dl; 95% CI 12.08, 13.93 [P < 0.001]) and the LDL cholesterol level (WMD 11.20 mg/dl; 95% CI 10.08, 12.32 [P < 0.001]) were higher than those in the comparator groups. Among patients treated with tofacitinib 10 mg twice daily, the mean percentage of increases in the HDL cholesterol level (WMD 15.21 mg/dl; 95% CI 13.28, 17.14 [P < 0.001]) and the LDL cholesterol level (WMD 15.42 mg/dl; 95% CI 11.77, 19.06 [P < 0.001]) were also higher than those in the comparator groups. No data were available for RA treated with other biologic agents or for SpA. CONCLUSION: In patients with RA treated with tocilizumab or tofacitinib but not with TNF antagonists, moderate changes in lipids are observed. Whether these changes pertain to the control of inflammation or to the mechanism of action of the biologic agents or tofacitinib remains undetermined.
Assuntos
Anticorpos Monoclonais Humanizados/uso terapêutico , Artrite Reumatoide/tratamento farmacológico , Produtos Biológicos/uso terapêutico , Lipídeos/sangue , Espondilartrite/tratamento farmacológico , Adulto , Idoso , Artrite Reumatoide/sangue , Doença Crônica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Piperidinas/uso terapêutico , Inibidores de Proteínas Quinases/uso terapêutico , Pirimidinas/uso terapêutico , Pirróis/uso terapêutico , Ensaios Clínicos Controlados Aleatórios como Assunto , Espondilartrite/sangue , Resultado do TratamentoRESUMO
UNLABELLED: : Familial cold autoinflammatory syndrome, Muckle-Wells syndrome (MWS), and chronic, infantile, neurological, cutaneous and articular (CINCA) syndrome are dominantly inherited autoinflammatory diseases associated to gain-of-function NLRP3 mutations and included in the cryopyrin-associated periodic syndromes (CAPS). A variable degree of somatic NLRP3 mosaicism has been detected in ≈35% of patients with CINCA. However, no data are currently available regarding the relevance of this mechanism in other CAPS phenotypes. OBJECTIVE: To evaluate somatic NLRP3 mosaicism as the disease-causing mechanism in patients with clinical CAPS phenotypes other than CINCA and NLRP3 mutation-negative. METHODS: NLRP3 analyses were performed by Sanger sequencing and by massively parallel sequencing. Apoptosis-associated Speck-like protein containing a CARD (ASC)-dependent nuclear factor kappa-light chain-enhancer of activated B cells (NF-κB) activation and transfection-induced THP-1 cell death assays determined the functional consequences of the detected variants. RESULTS: A variable degree (5.5-34.9%) of somatic NLRP3 mosaicism was detected in 12.5% of enrolled patients, all of them with a MWS phenotype. Six different missense variants, three novel (p.D303A, p.K355T and p.L411F), were identified. Bioinformatics and functional analyses confirmed that they were disease-causing, gain-of-function NLRP3 mutations. All patients treated with anti-interleukin1 drugs showed long-lasting positive responses. CONCLUSIONS: We herein show somatic NLRP3 mosaicism underlying MWS, probably representing a shared genetic mechanism in CAPS not restricted to CINCA syndrome. The data here described allowed definitive diagnoses of these patients, which had serious implications for gaining access to anti-interleukin 1 treatments under legal indication and for genetic counselling. The detection of somatic mosaicism is difficult when using conventional methods. Potential candidates should benefit from the use of modern genetic tools.
Assuntos
Proteínas de Transporte/genética , Síndromes Periódicas Associadas à Criopirina/genética , Mosaicismo , Adolescente , Povo Asiático/genética , Pré-Escolar , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Lactente , Recém-Nascido , Proteína 3 que Contém Domínio de Pirina da Família NLR , Análise de Sequência de DNA , População Branca/genéticaRESUMO
The aims of this study are to analyse the characteristics of septic arthritis stratified by age and to identify the predictors of treatment failure and mortality in septic arthritis. A retrospective single-centre study was conducted in patients with native septic arthritis between 1994 and 2012. The primary outcome was treatment failure. Secondary outcomes included mortality, complications, endocarditis, bacteraemia, hospital readmission and the duration of the hospital stay. Logistic regression analyses with a propensity score were performed to identify the predictors of response and mortality. Additional analyses were performed according to age and the initial treatment (surgery or conservative). A total of 186 patients were studied. The median (interquartile range) age was 64 (46, 74) years, and the percentage of male patients was 68.9%. A logistic regression analysis showed that Staphylococcus aureus infection [OR 2.39 (1.20-4.77), p = 0.013], endocarditis [OR 4.74 (1.16-19.24), p = 0.029] and the involvement of joints difficult to access with needle drainage [OR 2.33 (1.06-5.11), p = 0.034] predict treatment failure and that age [OR 1.27 (1.07 = 1.50), p = 0.005], the leucocyte count at baseline [OR 1.01 (1.00-1.02), p = 0.023], bacteraemia [OR 27.66 (1.39-551.20), p = 0.030], diabetes mellitus [OR 15.33 (1.36-172.67), p = 0.027] and chronic renal failure [OR 81.27 (3.32-1990.20), p = 0.007] predict mortality. No significant differences in treatment failure by age were found. In septic arthritis, the predictors of mortality and the predictors of treatment failure differ. The predictors of treatment failure concern local factors and systemic complications, whereas conditions related to the host's immune competence, such as age and comorbidities that hamper the host's response, predict mortality.
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Artrite Infecciosa/complicações , Artrite Infecciosa/mortalidade , Artrite Infecciosa/terapia , Articulações/microbiologia , Infecções Estafilocócicas/complicações , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Comorbidade , Feminino , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Retrospectivos , Falha de TratamentoRESUMO
OBJECTIVE: The aim of this study was to assess the risk of active tuberculosis (TB) in patients with immune-mediated inflammatory diseases treated with biologics and tofacitinib in randomized controlled trials (RCTs) and long-term extension (LTE) studies. METHODS: A systematic review of the English-language literature by was performed by searching the Medline, Embase, Cochrane and Web of Knowledge databases. The search strategy focused on synonyms of diseases, biologics and tofacitinib. Data from RCTs were combined to assess the rate of TB using a random effects model. The incidence rate (IR) of TB and its association with disease, location and treatment were assessed in LTE studies. RESULTS: The search captured 11 130 articles and abstracts. One-hundred RCTs (75 000 patients) and 63 LTE studies (80 774.45 patient-years) met the inclusion criteria. There were 31 TB cases with TNF inhibitors, 1 with abatacept and none with rituximab, tocilizumab, ustekinumab or tofacitinib. The odds ratio for TNF inhibitors was 1.92 (95% CI 0.91, 4.03, P = 0.085). In LTE studies, the IR of TB was >40/100 000 with tofacitinib and all biologics except rituximab. IR was higher in RA patients with anti-TNF monoclonal antibodies [307.71 (95% CI 184.79, 454.93)] than in those with rituximab [20.0 (95% CI 0.10, 60)] and etanercept [67.58 (95% CI 12.1, 163.94)] or AS, PsA and psoriasis with etanercept [60.01 (95% CI 3.6, 184.79)]. The IR of TB was higher in high-background TB areas. CONCLUSION: RCTs are not sensitive enough to assess the risk of reactivation of latent TB infection (LTBI). Disease, treatment and background TB rate are associated with different frequencies of active TB. The benefit/risk balance of preventing reactivation of LTBI in different backgrounds should be considered in clinical practice.
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Produtos Biológicos/efeitos adversos , Tuberculose Latente/etiologia , Piperidinas/efeitos adversos , Pirimidinas/efeitos adversos , Pirróis/efeitos adversos , Tuberculose/etiologia , Produtos Biológicos/uso terapêutico , Humanos , Incidência , Tuberculose Latente/epidemiologia , Piperidinas/uso terapêutico , Pirimidinas/uso terapêutico , Pirróis/uso terapêutico , Risco , Tuberculose/epidemiologiaAssuntos
Artrite Infecciosa/diagnóstico , Infecções por Bactérias Gram-Negativas/diagnóstico , Articulação do Joelho/microbiologia , Sphingomonas/isolamento & purificação , Adulto , Artrite Infecciosa/imunologia , Infecções por Bactérias Gram-Negativas/imunologia , Humanos , Imunocompetência , MasculinoRESUMO
Current methods for drug susceptibility testing of Mycobacterium tuberculosis are either costly or slow. As the prevalence of multidrug-resistant strains increases, the need for fast, reliable, and inexpensive methods that can also be applied in settings with scarce resources is obvious. We evaluated a rapid colorimetric nitrate reductase assay (NRA) for direct drug susceptibility testing of M. tuberculosis directly from clinical sputum samples with positive microscopy results for acid-fast bacilli with more than 10 acid-fast bacilli per high-power field. We have saved valuable time by omitting the preisolation step. The sensitivity (ability to detect true drug resistance) and specificity (ability to detect true drug susceptibility) of the direct NRA, using the direct proportion method as the reference, were 100 and 100%, 93 and 100%, 76 and 100%, and 55 and 99% for rifampin, isoniazid, streptomycin, and ethambutol, respectively, when tested on M. tuberculosis strains present in 121 samples. The results were in most cases available in 14 days. The direct NRA could be used as a rapid, inexpensive, and accurate method to determine rifampin and isoniazid susceptibility directly from sputum. The technique might become a valid alternative to traditional methods, especially in low-income countries.