Advances in the development of new vaccines for tuberculosis and Brazil's role in the effort forward the end TB strategy.

Tuberculosis (TB) continues to be the world's leading killer of infectious diseases. Despite global efforts to gradually reduce the number of annual deaths and the incidence of this disease, the coronavirus disease 19 (COVID-19) pandemic caused decreased in TB detection and affected the prompt treatment TB which led to a setback to the 2019 rates. However, the development and testing of new TB vaccines has not stopped and now presents the possibility of implanting in the next five years a new vaccine that is affordable and might be used in the various key vulnerable populations affected by TB. Then, this assay aimed to discuss the main vaccines developed against TB that shortly could be selected and used worldwide, and additionally, evidence the Brazilian potential candidates' vaccines in developing in Brazil that could be considered among those in level advanced to TB end.

PPE59 antibodies in tuberculous patients and potential use for diagnosis when assayed with other rapid biomarkers.

BACKGROUND: PPE 59, which is absent from bacillus Calmette Guérin (BCG) strains, seems to induce a humoral immune response in patients with tuberculosis (TB). Additional studies are needed to better evaluate this protein in immune response to tuberculosis. OBJECTIVES: To evaluate the response of antibodies to PPE59 in TB individuals, its combination with IgG response to other, previously tested mycobacterial antigens (Ag) and with sputum smear microbiology (SM) results. METHODS: We have cloned and expressed the rv3429 gene that encodes PPE59, then IgG, IgM, and IgA against PPE59 antigens measured by enzyme-linked immunosorbent assay (ELISA) in 212 sera samples obtained from the following subject cohorts: TB residents from Italy (79) and in Brazil (52); and an all-Brazilian cohort of 55 patients with other respiratory disorders; 10 patients infected with non-tuberculous mycobacteria, and 16 asymptomatic subjects. Drawing on results from a previous study(17) of serum samples from Brazilian subjects tested for IgG by ELISA against mycobacterial antigens ESAT-6, 16kDa, MT10.3, MPT-64 and 38kDa, the results were analysed in combination with those of the PPE59 and SM tests. FINDINGS: Keeping the specificity rate at 97%, the overall PPE59 IgA sensitivity was 42.7%, while IgG and IgM showed lower performance (p < 0.0001). Combining PPE59 IgA/16kDa IgG results increased sensitivity to 71%, and even higher rates when the results were combined with SM results (86.5%, p = 0.001), at 88.9% specificity. Positive IgA was associated with pulmonary image alterations of high TB probability (p < 0.05). MAIN CONCLUSIONS: Tests with TB patients found a moderate frequency of positivity for PPE59 IgA. However, the higher level of sensitivity attained in combination with PPE59 IgA/16kDa IgG/SM results unheard of before, although imperfect, suggests that this may be a potential additional tool for rapid detection of TB in low-resource areas.

Isoniazid Monoresistance and Antituberculosis Treatment Outcome in Persons With Pulmonary Tuberculosis in Brazil.

Background: The high burden of drug-resistant tuberculosis (TB) is a problem to achieve the goals of the End TB Strategy by 2035. Whether isoniazid monoresistance (Hr) affects anti-TB treatment (ATT) outcomes remains unknown in high-burden countries. Methods: We evaluated determinants of ATT outcome among pulmonary TB cases reported to the National Notifiable Disease Information System (SINAN) between June 2015 and June 2019, according to drug sensitivity testing (DST) results. Binomial logistic regression models were employed to evaluate whether Hr was associated with an unfavorable ATT outcome: death or failure, compared to cure or treatment completion. Results: Among 60 804 TB cases reported in SINAN, 21 197 (34.9%) were included in the study. In this database, the frequency of unfavorable outcomes was significantly higher in those with Hr in contrast to isoniazid-sensitive persons with pulmonary TB (9.1% vs 3.05%; P < .001). Using a binomial logistic regression model, Hr was independently associated with unfavorable outcomes (odds ratio, 3.34 [95% confidence interval, 2.06-5.40]; P < .001). Conclusions: Hr detected prior to ATT was predictive of unfavorable outcomes at the national level in Brazil. Our data reinforce the need for high-TB-burden countries to prioritize DST to detect Hr. Effective treatment regimens for Hr-TB are needed to improve outcomes.

Advances in the development of new vaccines for tuberculosis and Brazil’s role in the effort forward the end TB strategy

Tuberculosis (TB) continues to be the world’s leading killer of infectious diseases. Despite global efforts to gradually reduce the number of annual deaths and the incidence of this disease, the coronavirus disease 19 (COVID-19) pandemic caused decreased in TB detection and affected the prompt treatment TB which led to a setback to the 2019 rates. However, the development and testing of new TB vaccines has not stopped and now presents the possibility of implanting in the next five years a new vaccine that is affordable and might be used in the various key vulnerable populations affected by TB. Then, this assay aimed to discuss the main vaccines developed against TB that shortly could be selected and used worldwide, and additionally, evidence the Brazilian potential candidates’ vaccines in developing in Brazil that could be considered among those in level advanced to TB end.

PPE59 antibodies in tuberculous patients and potential use for diagnosis when assayed with other rapid biomarkers

BACKGROUND PPE 59, which is absent from bacillus Calmette Guérin (BCG) strains, seems to induce a humoral immune response in patients with tuberculosis (TB). Additional studies are needed to better evaluate this protein in immune response to tuberculosis. OBJECTIVES To evaluate the response of antibodies to PPE59 in TB individuals, its combination with IgG response to other, previously tested mycobacterial antigens (Ag) and with sputum smear microbiology (SM) results. METHODS We have cloned and expressed the rv3429 gene that encodes PPE59, then IgG, IgM, and IgA against PPE59 antigens measured by enzyme-linked immunosorbent assay (ELISA) in 212 sera samples obtained from the following subject cohorts: TB residents from Italy (79) and in Brazil (52); and an all-Brazilian cohort of 55 patients with other respiratory disorders; 10 patients infected with non-tuberculous mycobacteria, and 16 asymptomatic subjects. Drawing on results from a previous study(17) of serum samples from Brazilian subjects tested for IgG by ELISA against mycobacterial antigens ESAT-6, 16kDa, MT10.3, MPT-64 and 38kDa, the results were analysed in combination with those of the PPE59 and SM tests. FINDINGS Keeping the specificity rate at 97%, the overall PPE59 IgA sensitivity was 42.7%, while IgG and IgM showed lower performance (p < 0.0001). Combining PPE59 IgA/16kDa IgG results increased sensitivity to 71%, and even higher rates when the results were combined with SM results (86.5%, p = 0.001), at 88.9% specificity. Positive IgA was associated with pulmonary image alterations of high TB probability (p < 0.05). MAIN CONCLUSIONS Tests with TB patients found a moderate frequency of positivity for PPE59 IgA. However, the higher level of sensitivity attained in combination with PPE59 IgA/16kDa IgG/SM results unheard of before, although imperfect, suggests that this may be a potential additional tool for rapid detection of TB in low-resource areas.

Advances in the development of new vaccines for tuberculosis and Brazil's role in the effort forward the end TB strategy

Tuberculosis (TB) continues to be the world's leading killer of infectious diseases. Despite global efforts to gradually reduce the number of annual deaths and the incidence of this disease, the coronavirus disease 19 (COVID-19) pandemic caused decreased in TB detection and affected the prompt treatment TB which led to a setback to the 2019 rates. However, the development and testing of new TB vaccines has not stopped and now presents the possibility of implanting in the next five years a new vaccine that is affordable and might be used in the various key vulnerable populations affected by TB. Then, this assay aimed to discuss the main vaccines developed against TB that shortly could be selected and used worldwide, and additionally, evidence the Brazilian potential candidates' vaccines in developing in Brazil that could be considered among those in level advanced to TB end.

Clinical trials for Chagas disease: etiological and pathophysiological treatment.

Chagas disease (CD) is caused by the flagellate protozoan Trypanosoma cruzi. It is endemic in Latin America. Nowadays around 6 million people are affected worldwide, and 75 million are still at risk. CD has two evolutive phases, acute and chronic. The acute phase is mostly asymptomatic, or presenting unspecific symptoms which makes it hard to diagnose. At the chronic phase, patients can stay in the indeterminate form or develop cardiac and/or digestive manifestations. The two trypanocide drugs available for the treatment of CD are benznidazole (BZ) and nifurtimox (NFX), introduced in the clinic more than five decades ago. WHO recommends treatment for patients at the acute phase, at risk of congenital infection, for immunosuppressed patients and children with chronic infection. A high cure rate is seen at the CD acute phase but better treatment schemes still need to be investigated for the chronic phase. There are some limitations within the use of the trypanocide drugs, with side effects occurring in about 40% of the patients, that can lead patients to interrupt treatment. In addition, patients with advanced heart problems should not be treated with BZ. This is a neglected disease, discovered 114 years ago that still has no drug effective for their chronic phase. Multiple social economic and cultural barriers influence CD research. The high cost of the development of new drugs, in addition to the low economical return, results in the lack of investment. More economic support is required from governments and pharmaceutical companies on the development of more research for CD treatment. Two approaches stand out: repositioning and combination of drugs, witch drastically decrease the cost of this process, when compared to the development of a new drug. Here we discuss the progress of the clinical trials for the etiological and pathophysiological treatment for CD. In summary, more studies are needed to propose a new drug for CD. Therefore, BZ is still the best option for CD. The trials in course should clarify more about new treatment regimens, but it is already possible to indicate that dosage and time of treatment need to be adjusted.

Clinical, laboratory, and radiographic aspects of patients with pulmonary tuberculosis and dysglycemia and tuberculosis treatment outcomes.

OBJECTIVE: To analyze the association of dysglycemia with clinical, laboratory, and radiographic characteristics of patients with pulmonary tuberculosis (PTB), as well as with their tuberculosis treatment outcomes. METHODS: This was a longitudinal study involving 140 patients diagnosed with PTB (positive cultures for Mycobacterium tuberculosis or positive Xpert MTB/RIF results from sputum samples). Patients were evaluated at diagnosis (M0), after completing the second month of treatment (M2), and at the end of treatment (MEND). At M0, the patients were classified into three groups: normoglycemia+PTB (NGTB); pre-diabetes mellitus+PTB (PDMTB), and diabetes mellitus+PTB (DMTB), in accordance with glycated hemoglobin levels (< 5.7%, 5.7%-6.4%, and ≥ 6.5%, respectively). Treatment outcomes were classified as favorable (cure or treatment completion) and unfavorable (death, loss to follow-up, or treatment failure). RESULTS: In our sample, 76 patients (61.4%) had dysglycemia, 20 of whom (14.3%) had DM at M0. The patients with dysglycemia, in comparison with those in the NGTB group, more frequently presented with positive sputum smear microscopy (94.2% vs. 75.9%; p = 0.003); cavities (80.2% vs. 63.0%; p = 0.03); bilateral lesions (67.4% vs. 46.0%; p = 0.02); and higher median of affected thirds of the lungs (3.0 vs. 2.0; p = 0.03) on chest radiography. No significant differences regarding outcomes were found among the groups, but tuberculosis lethality was higher in the DMTB group than in the PDMTB and NGTB groups (20% vs. 2.2%). CONCLUSIONS: PTB patients with dysglycemia had laboratory and radiographic manifestations indicative of more advanced disease, and the risk of death was higher in the DMTB group. These findings reinforce the recommendation for early screening for DM in patients with newly diagnosed tuberculosis in order to reduce the risk of death during treatment.

Selenium, TGF-Beta and Infectious Endemic Cardiopathy: Lessons from Benchwork to Clinical Application in Chagas Disease.

For over 60 years, selenium (Se) has been known as an essential microelement to many biological functions, including cardiovascular homeostasis. This review presents a compilation of studies conducted in the past 20 years related to chronic Chagas disease cardiomyopathy (CCC), caused by Trypanosoma cruzi infection, a neglected disease that represents a global burden, especially in Latin America. Experimental and clinical data indicate that Se may be used as a complementary therapy to prevent heart failure and improve heart function. Starting from the main questions "Is Se deficiency related to heart inflammation and arrhythmogenesis in CCC?" and "Could Se be recommended as a therapeutic strategy for CCC?", we show evidence implicating the complex and multidetermined CCC physiopathology, discussing its possible interplays with the multifunctional cytokine TGF-ß as regulators of immune response and fibrosis. We present two new proposals to face this global public health challenge in vulnerable populations affected by this parasitic disease: fibrosis modulation mediated by TGF-ß pathways and the possible use of selenoproteins as antioxidants regulating the increased reactive oxygen stress present in CCC inflammatory environments. We assess the opportunity to consider the beneficial effects of Se in preventing heart failure as a concept to be applied for CCC patients.

The Effect of Diabetes and Prediabetes on Antituberculosis Treatment Outcomes: A Multicenter Prospective Cohort Study.

BACKGROUND: It is unclear whether diabetes or prediabetes affects unfavorable treatment outcomes and death in people with tuberculosis (PWTB). METHODS: Culture-confirmed, drug-susceptible PWTB, enrolled in the Regional Prospective Observational Research in Tuberculosis (RePORT)-Brazil cohort between 2015 and 2019 (N = 643) were stratified based on glycemic status according to baseline glycated hemoglobin. Unfavorable tuberculosis (TB) outcome was defined as treatment failure or modification, recurrence, or death; favorable outcome was cure or treatment completion. We corroborated the findings using data from PWTB reported to the Brazilian National System of Diseases Notification (SINAN) during 2015-2019 (N = 20 989). Logistic regression models evaluated associations between glycemic status and outcomes. RESULTS: In both cohorts, in univariate analysis, unfavorable outcomes were more frequently associated with smoking, illicit drug use, and human immunodeficiency virus infection. Diabetes, but not prediabetes, was associated with unfavorable outcomes in the RePORT-Brazil (adjusted relative risk [aRR], 2.45; P < .001) and SINAN (aRR, 1.76; P < .001) cohorts. Furthermore, diabetes was associated with high risk of death (during TB treatment) in both RePORT-Brazil (aRR, 2.16; P = .040) and SINAN (aRR, 1.93; P = .001). CONCLUSIONS: Diabetes was associated with an increased risk of unfavorable outcomes and mortality in Brazilian PWTB. Interventions to improve TB treatment outcomes in persons with diabetes are needed.

Clinical, laboratory, and radiographic aspects of patients with pulmonary tuberculosis and dysglycemia and tuberculosis treatment outcomes / Aspectos clínicos, laboratoriais e radiográficos de pacientes com tuberculose pulmonar e disglicemia e desfechos do tratamento da tuberculose

ABSTRACT Objective: To analyze the association of dysglycemia with clinical, laboratory, and radiographic characteristics of patients with pulmonary tuberculosis (PTB), as well as with their tuberculosis treatment outcomes. Methods: This was a longitudinal study involving 140 patients diagnosed with PTB (positive cultures for Mycobacterium tuberculosis or positive Xpert MTB/RIF results from sputum samples). Patients were evaluated at diagnosis (M0), after completing the second month of treatment (M2), and at the end of treatment (MEND). At M0, the patients were classified into three groups: normoglycemia+PTB (NGTB); pre-diabetes mellitus+PTB (PDMTB), and diabetes mellitus+PTB (DMTB), in accordance with glycated hemoglobin levels (< 5.7%, 5.7%-6.4%, and ≥ 6.5%, respectively). Treatment outcomes were classified as favorable (cure or treatment completion) and unfavorable (death, loss to follow-up, or treatment failure). Results: In our sample, 76 patients (61.4%) had dysglycemia, 20 of whom (14.3%) had DM at M0. The patients with dysglycemia, in comparison with those in the NGTB group, more frequently presented with positive sputum smear microscopy (94.2% vs. 75.9%; p = 0.003); cavities (80.2% vs. 63.0%; p = 0.03); bilateral lesions (67.4% vs. 46.0%; p = 0.02); and higher median of affected thirds of the lungs (3.0 vs. 2.0; p = 0.03) on chest radiography. No significant differences regarding outcomes were found among the groups, but tuberculosis lethality was higher in the DMTB group than in the PDMTB and NGTB groups (20% vs. 2.2%). Conclusions: PTB patients with dysglycemia had laboratory and radiographic manifestations indicative of more advanced disease, and the risk of death was higher in the DMTB group. These findings reinforce the recommendation for early screening for DM in patients with newly diagnosed tuberculosis in order to reduce the risk of death during treatment.

RESUMO Objetivo: Analisar a associação de disglicemia e características clínicas, laboratoriais e radiográficas em pacientes com tuberculose pulmonar (TBP), bem como a associação de disglicemia e desfechos do tratamento da tuberculose. Métodos: Estudo longitudinal com 140 pacientes com diagnóstico de TBP (culturas de escarro positivas para Mycobacterium tuberculosis ou resultados positivos do teste Xpert MTB/RIF em amostras de escarro). Os pacientes foram avaliados no momento do diagnóstico (M0), após dois meses de tratamento (M2) e no fim do tratamento (MFIM). Em M0, os pacientes foram divididos em três grupos: normoglicemia+TBP (NGTB); pré-diabetes mellitus+TBP (PDMTB) e diabetes mellitus+TBP (DMTB), de acordo com os níveis de hemoglobina glicada (< 5,7%, 5,7%-6,4% e ≥ 6,5%, respectivamente). Os desfechos do tratamento foram classificados em favoráveis (cura ou conclusão do tratamento) e desfavoráveis (óbito, perda de seguimento ou falência do tratamento). Resultados: Em nossa amostra, 76 pacientes (61,4%) apresentavam disglicemia, 20 (14,3%) dos quais apresentavam DM em M0. Os pacientes com disglicemia, em comparação com os do grupo NGTB, apresentaram mais frequentemente baciloscopia de escarro positiva (94,2% vs. 75,9%; p = 0,003); cavidades (80,2% vs. 63,0%; p = 0,03); lesões bilaterais (67,4% vs. 46,0%; p = 0,02) e maior mediana de terços pulmonares acometidos (3,0 vs. 2,0; p = 0,03) na radiografia de tórax. Não foram observadas diferenças significativas entre os grupos quanto aos desfechos, mas a letalidade da tuberculose foi maior no grupo DMTB do que nos grupos PDMTB e NGTB (20% vs. 2,2%). Conclusões: Pacientes com TBP e disglicemia apresentaram manifestações laboratoriais e radiográficas indicativas de doença mais avançada, e o risco de óbito foi maior no grupo DMTB. Esses achados reforçam a recomendação de detecção precoce de DM em pacientes com tuberculose recém-diagnosticada, a fim de reduzir o risco de óbito durante o tratamento.

Effects of Selenium treatment on cardiac function in Chagas heart disease: Results from the STCC randomized Trial.

BACKGROUND: Chagas disease (caused by Trypanosoma cruzi infection) evolves to chronic chagasic cardiomyopathy (CCC) affecting 1.8 million people worldwide. This is the first randomized, placebo-controlled, double-blinded, clinical trial designed to estimate efficacy and safety of selenium (Se) treatment in CCC. METHODS: 66 patients with CCC stages B1 (left ventricular ejection fraction [LVEF] > 45% and no heart failure; n = 54) or B2 (LVEF < 45% and no heart failure; n = 12) were randomly assigned to receive 100 mcg/day sodium selenite (Se, n = 32) or placebo (Pla, n = 34) for one year (study period: May 2014-September 2018). LVEF changes over time and adverse effects were investigated. Trial registration number: NCT00875173 (clinicaltrials.gov). FINDINGS: No significant differences between the two groups were observed for the primary outcome: mean LVEF after 6 (ß= +1.1 p = 0.51 for Se vs Pla) and 12 months (ß= +2.1; p = 0.23). In a subgroup analysis, statistically significant longitudinal changes were observed for mean LVEF in the stage B2 subgroup (ß= +10.1; p = 0.02 for Se [n = 4] vs Pla [n = 8]). Se treatment was safe for CCC patients, and the few adverse effects observed were similarly distributed across the two groups. INTERPRETATION: Se treatment did not improve cardiac function (evaluated from LVEF) in CCC. However, in the subgroup of patients at B2 stage, a potential beneficial influence of Se was observed. Complementary studies are necessary to explore diverse Se dose and/or associations in different CCC stages (B2 and C), as well as in A and B1 stages with longer follow-up. FUNDING: Brazilian Ministry of Health, Fiocruz, CNPq, FAPERJ.

Pre-Treatment Neutrophil Count as a Predictor of Antituberculosis Therapy Outcomes: A Multicenter Prospective Cohort Study.

Background: Neutrophils have been associated with lung tissue damage in many diseases, including tuberculosis (TB). Whether neutrophil count can serve as a predictor of adverse treatment outcomes is unknown. Methods: We prospectively assessed 936 patients (172 HIV-seropositive) with culture-confirmed pulmonary TB, enrolled in a multicenter prospective cohort study from different regions in Brazil, from June 2015 to June 2019, and were followed up to two years. TB patients had a baseline visit before treatment (month 0) and visits at month 2 and 6 (or at the end of TB treatment). Smear microscopy, and culture for Mycobacterium tuberculosis (MTB) were performed at TB diagnosis and during follow-up. Complete blood counts were measured at baseline. Treatment outcome was defined as either unfavorable (death, treatment failure or TB recurrence) or favorable (cure or treatment completion). We performed multivariable logistic regression, with propensity score regression adjustment, to estimate the association between neutrophil count with MTB culture result at month 2 and unfavorable treatment outcome. We used a propensity score adjustment instead of a fully adjusted regression model due to the relatively low number of outcomes. Results: Among 682 patients who had MTB culture results at month 2, 40 (5.9%) had a positive result. After regression with propensity score adjustment, no significant association between baseline neutrophil count (103/mm3) and positive MTB culture at month 2 was found among either HIV-seronegative (OR = 1.06, 95% CI = [0.95;1.19] or HIV-seropositive patients (OR = 0.77, 95% CI = [0.51; 1.20]). Of 691 TB patients followed up for at least 18 months and up to 24 months, 635 (91.9%) were either cured or completed treatment, and 56 (8.1%) had an unfavorable treatment outcome. A multivariable regression with propensity score adjustment found an association between higher neutrophil count (103/mm3) at baseline and unfavorable outcome among HIV-seronegative patients [OR= 1.17 (95% CI= [1.06;1.30]). In addition, adjusted Cox regression found that higher baseline neutrophil count (103/mm3) was associated with unfavorable treatment outcomes overall and among HIV-seronegative patients (HR= 1.16 (95% CI = [1.05;1.27]). Conclusion: Increased neutrophil count prior to anti-TB treatment initiation was associated with unfavorable treatment outcomes, particularly among HIV-seronegative patients. Further prospective studies evaluating neutrophil count in response to drug treatment and association with TB treatment outcomes are warranted.

Pediatric tuberculosis in the metropolitan area of Rio de Janeiro.

AIM: To evaluate the clinical characteristics, diagnostic approach, and treatment outcomes of tuberculosis (TB) in children living in a high-burden metropolitan area. METHODS: This was a retrospective study, based on a medical chart review, involving children under 15 years old treated for TB between 2007 and 2016, in four primary health units (PHU) and three reference centers (RC) in five cities of Rio de Janeiro metropolitan area. Factors associated with TB treatment setting, microbiological diagnosis, and treatment outcomes were evaluated. RESULTS: A total of 544 children were enrolled; 71% were treated in PHU, 36% were under 5 years old, and 72% had pulmonary TB (PTB). The HIV prevalence was 10% (31/322). Fifty-three percent had at least one microbiological test for TB, 68% of them (196/287) had TB confirmed. Among 222 children with previous TB contact, information on LTBI was available for 78 (35%), and only 17% (13/78) were treated. Extrapulmonary TB (56% vs 32%), microbiologically confirmed TB (77% vs 60%), and HIV positivity (18.5% vs 4.0%) were significantly more frequent in RC. Treatment in RC (odds ratio (OR) 3.08, 95% confidence interval (CI) 1.74-5.44) and PTB (OR 2.47, 95% CI 1.34-4.56) were independently associated with a microbiological diagnosis of TB. The treatment success rate was 85%. In the logistic regression analysis, HIV-infected children had a 2.5-fold higher risk of an unfavorable outcome (OR 2.53, 95% CI 1.0-6.38; p = 0.05). CONCLUSIONS: Opportunities for TB prevention and early TB treatment are missed due to suboptimal close contact screening. Microbiological diagnosis of TB and drug susceptibility testing in children should be made available through more sensitive and accessible tests.

Typing of Mycobacterium tuberculosis strains isolated in Community Health Centers of Rio de Janeiro City, Brazil.

Fingerprinting of Mycobacterium tuberculosis strains from tuberculosis (TB) patients attended in Community Health Centers (CHCs) of Rio de Janeiro was performed to verify possible risk factors for TB transmission. A prospective community-based study was performed during the period of July 1996 to December 1996 by collecting sputum samples of 489 patients in 11 different CHCs in four different planning areas (APs) of the city. Bacteriological, clinical, and epidemiological information was collected and M. tuberculosis genotypes defined after restriction fragment length polymorphism (IS6110-RFLP) and double repetitive element (DRE) fingerprinting of RFLP-clustered cases. Risk factors for TB transmission were looked for using three levels of cluster stringency. Among 349 (71%) positive cultures obtained, IS6110-RFLP typing could be performed on strains from 153 different patients. When using identity of RFLP patterns as cluster definition, 49 (32%) of the strains belonged to a cluster and none of the clinical or epidemiologic characteristics was associated with higher clustering levels. However, higher clustering level was observed in the AP including the central region of the city when compared to others. This strongly suggests that more recent transmission occurs in that area and this may be related with higher incidence of TB and HIV in this region.