Restimulation-induced T-cell death through NTB-A/SAP signaling pathway is impaired in tuberculosis patients with depressed immune responses.

Production of IFN-γ contributes to host defense against Mycobacterium tuberculosis (Mtb) infection. We previously demonstrated that Signaling lymphocytic activation molecule-associated protein (SAP) expression on cells from tuberculosis (TB) patients was inversely correlated with IFN-γ production. Here we first investigated the role of NK, T- and B-cell antigen (NTB-A)/SAP pathway in the regulation of Th1 response against Mtb. Upon antigen stimulation, NTB-A phosphorylation rapidly increases and afterwards modulates IFN-γ and IL-17 secretion. To sustain a healthy immune system, controlled expansion and contraction of lymphocytes, both during and after an adaptive immune response, is essential. Besides, restimulation-induced cell death (RICD) results in an essential homeostatic mechanism for precluding excess T-cell accumulation and associated immunopathology during the course of certain infections. Accordingly, we found that the NTB-A/SAP pathway was required for RICD during active tuberculosis. In low responder (LR) TB patients, impaired RICD was associated with diminished FASL levels, IL-2 production and CD25high expression after cell-restimulation. Interestingly, we next observed that SAP mediated the recruitment of the Src-related kinase FYNT, only in T cells from LR TB patients that were resistant to RICD. Together, we showed that the NTB-A/SAP pathway regulates T-cell activation and RICD during human TB. Moreover, the NTB-A/SAP/FYNT axis promotes polarization to an unfavorable Th2-phenotype.

The impact of IFN-γ receptor on SLPI expression in active tuberculosis: association with disease severity.

Interferon (IFN)-γ displays a critical role in tuberculosis (TB), modulating the innate and adaptive immune responses. Previously, we reported that secretory leukocyte protease inhibitor (SLPI) is a pattern recognition receptor with anti-mycobacterial activity against Mycobacterium tuberculosis (Mtb). Herein, we determined whether IFN-γ modulated the levels of SLPI in TB patients. Plasma levels of SLPI and IFN-γ were studied in healthy donors (HDs) and TB patients. Peripheral blood mononuclear cells from HDs and patients with TB or defective IFN-γ receptor 1* were stimulated with Mtb antigen and SLPI, and IFN-γR expression levels were measured. Both SLPI and IFN-γ were significantly enhanced in plasma from those with TB compared with HDs. A direct association between SLPI levels and the severity of TB was detected. In addition, Mtb antigen stimulation decreased the SLPI produced by peripheral blood mononuclear cells from HDs, but not from TB or IFN-γR patients. Neutralization of IFN-γ reversed the inhibition of SLPI induced by Mtb antigen in HDs, but not in TB patients. Furthermore, recombinant IFN-γ was unable to modify the expression of SLPI in TB patients. Finally, IFN-γR expression was lower in TB compared with HD peripheral blood mononuclear cells. These results show that Mtb-induced IFN-γ down-modulated SLPI levels by signaling through the IFN-γR in HDs. This inhibitory mechanism was not observed in TB, probably because of the low expression of IFN-γR detected in these individuals.

Phosphorylation of mitogen-activated protein kinases contributes to interferon γ production in response to Mycobacterium tuberculosis.

Immune control of Mycobacterium tuberculosis depends on interferon γ (IFN-γ)-producing CD4(+) lymphocytes. Previous studies have shown that T cells from patients with tuberculosis produce less IFN-γ, compared with healthy donors, in response to mycobacterial antigens, although IFN-γ responses to mitogens are preserved. In this work, we found that M. tuberculosis-induced IFN-γ production by human T cells correlated with phosphorylation of the mitogen-activated protein kinases (MAPKs), extracellular signal-regulated kinase (ERK), and p38. Moreover, the majority of IFN-γ-producing T cells expressed signaling lymphocyte activation molecule (SLAM), and SLAM activation further increased ERK phosphorylation. Interestingly, patients with tuberculosis had delayed activation of ERK and p38, and this was most marked in patients with the poorest IFN-γ responses (ie, low responders). Besides, SLAM signaling failed to phosphorylate ERK in low responders. Our findings suggest that activation of p38 and ERK, in part through SLAM, mediates T-cell IFN-γ production in response to M. tuberculosis, a pathway that is defective in patients with tuberculosis.

[Treatment of drug-resistant tuberculosis in adults and children. A narrative review]. / Tratamiento de la tuberculosis drogorresistente en adultos y niños. Revisión narrativa.

Since 2018, important changes in the treatment of drug-resistant tuberculosis have been produced in the light of new evidence. The discovery of new anti-tuberculosis drugs, such as bedaquiline and nitroimidazopirane derivatives, as well as the use of repurposed drugs, led to international organizations to recommend new, totally oral, treatment regimens for mono-resistant and multidrug-resistant tuberculosis, leaving aside the prolonged use of injectables, with their inherent toxicity and discomfort. Some definitions of drug-resistant tuberculosis have changed. The duration of treatment is also under review, leading some new regimens under study, such as BPaL (bedaquiline, pretomanid and linezolid), to a duration similar to that for treating susceptible tuberculosis. In this narrative review, we describe the new definitions, some basic diagnostic aspects, the pharmacological aspects, and the new classification of drugs to be used in the treatment of drug-resistant tuberculosis as well as the currently proposed schemes to treat it available within the Argentinean context. Finally, we include a brief review of ongoing clinical trials on new shortened treatments.

Desde 2018 han surgido a la luz de la evidencia importantes cambios en el tratamiento de la tuberculosis drogorresistente. El descubrimiento de nuevas drogas antituberculosis, como la bedaquilina y los derivados de nitroimidazopiranos, así como la utilización de drogas repropuestas, llevó a la recomendación de organismos internacionales de nuevos esquemas de tratamiento de la tuberculosis monorresistente y multidrogorresistente que son totalmente orales y así dejan de lado el uso prolongado de inyectables, con su inherente toxicidad e incomodidad. Algunas de las definiciones de tuberculosis drogorresistente han cambiado. También está en revisión el tiempo de su tratamiento y con algunos nuevos esquemas en estudio, como el BpaL (bedaquilina, pretomanid y linezolid), se ha logrado una duración similar a la del tratamiento de la tuberculosis pansensible. En esta revisión bibliográfica narrativa describimos las nuevas definiciones, algunos aspectos diagnósticos básicos, los aspectos farmacológicos y la nueva clasificación de las drogas a utilizar en el tratamiento de la tuberculosis drogorresistente, así como los esquemas actualmente propuestos para tratarla, contextualizados con la realidad nacional. Finalizamos con una breve reseña de los estudios clínicos en curso de nuevos esquemas acortados de tratamiento.

Circulating Monocyte-Like Myeloid Derived Suppressor Cells and CD16 Positive Monocytes Correlate With Immunological Responsiveness of Tuberculosis Patients.

Alterations of myeloid cell populations have been reported in patients with tuberculosis (TB). In this work, we studied the relationship between myeloid-derived suppressor cells (MDSC) and monocytes subsets with the immunological responsiveness of TB patients. Individuals with active TB were classified as low responders (LR-TB) or high responders (HR-TB) according to their T cell responses against a cell lysate of Mycobacterium tuberculosis (Mtb-Ag). Thus, LR-TB, individuals with severe disease, display a weaker immune response to Mtb compare to HR-TB, subjects with strong immunity against the bacteria. We observed that LR-TB presented higher percentages of CD16 positive monocytes as compared to HR-TB and healthy donors. Moreover, monocyte-like (M-MDSC) and polymorphonuclear-like (PMN-MDSC) MDSC were increased in patients and the proportion of M-MDSC inversely correlated with IFN-γ levels released after Mtb-Ag stimulation in HR-TB. We also found that LR-TB displayed the highest percentages of circulating M-MDSC. These results demonstrate that CD16 positive monocytes and M-MDSC frequencies could be used as another immunological classification parameter. Interestingly, in LR-TB, frequencies of CD16 positive monocytes and M-MDSC were restored after only three weeks of anti-TB treatment. Together, our findings show a link between the immunological status of TB patients and the levels of different circulating myeloid cell populations.

IFN-γ and IgG responses to Mycobacterium tuberculosis latency antigen Rv2626c differentiate remote from recent tuberculosis infection.

Tuberculin skin test (TST) and IFN-γ release assays are currently used to detect Mycobacterium tuberculosis (Mtb) infection but none of them differentiate active from latent infection (LTBI). Since improved tests to diagnose Mtb infection are required, we studied the immune response to Mtb latency antigen Rv2626c in individuals exposed to the bacteria during different periods. Tuberculosis patients (TB), TB close contacts (CC: subjects exposed to Mtb for less than three months) and healthcare workers (HW: individuals exposed to Mtb at least two years) were recruited and QuantiFERON (QFT) assay, TST and IFN-γ secretion to Rv2626c were analyzed. Twenty-two percent of the individuals assessed had discordant results between QFT and TST tests. Furthermore, QFT negative and QFT positive individuals produced differential levels of IFN-γ against Rv2626c, in direct association with their exposure period to Mtb. Actually, 91% of CC QFT negative subjects secreted low levels of IFN-γ to Rv2626c, whereas 43% of HW QFT negative people produced elevated IFN-γ amounts against Rv2626c. Conversely, 69% of CC QFT positive subjects didn´t produce IFN-γ to Rv2626c. Interestingly, a similar pattern of IgG anti-Rv2626c plasma levels was observed. Therefore, determination of IFN-γ and IgG levels against the dormancy antigen Rv2626c allows to identify established LTBI.

The IFNG rs1861494 Single Nucleotide Polymorphism Is Associated with Protection against Tuberculosis Disease in Argentina.

Interferon gamma (IFNG) plays a key role during Mycobacterium tuberculosis (Mtb) infection, and several polymorphisms located in its gene are associated with risk of tuberculosis in diverse populations. Nevertheless, the genetic resistance/susceptibility to tuberculosis in Argentina is unknown. The IFNG rs1861494 polymorphism (G→A) was reported to alter the binding of transcription factors to this region, influencing IFNG production. Using a case-control study, we found an association between the AA and AG genotypes and tuberculosis resistance (AA vs. GG: odds ratio (OR) = 0.235, p-value = 0.012; AG vs. GG: OR = 0.303, p-value = 0.044; AA vs. AG: OR = 0.776, p-value = 0.427; AA + AG vs. GG: OR = 0.270, p-value = 0.022). Moreover, Mtb-antigen stimulated peripheral blood mononuclear cells (PBMCs) from healthy donors and AA carriers secreted the highest amounts of IFNG in culture supernatants (p-value = 0.034) and presented the greatest percentage of CD4⁺IFNG⁺ lymphocytes (p-value = 0.035), in comparison with GG carriers. No association between the polymorphism and clinical parameters of tuberculosis severity was detected. However, our findings indicate that the rs1861494 single nucleotide polymorphism (SNP) could be considered as a biomarker of tuberculosis resistance in the Argentinean population.

[Tuberculosis treatment. A practical guide elaborated by the tuberculosis section, Argentine Association of Respiratory Medicine]. / Tratamiento de la tuberculosis. Guia practica elaborada por la seccion tuberculosis, Asociacion Argentina de Medicina Respiratoria.

Tuberculosis is a worldwide prevalent disease. The emergence of multidrug-resistant strains spurred the search for new drugs. There are several tuberculosis treatment guidelines, international and local in a programmatic approach. An Argentinean specialists panel draw practical guidelines based in clinical criteria and the local and international bibliography through consensus meetings, including issues as: antituberculosis drugs available in Argentina, initial and re-treatement modalities, special situations treatment, adverse reactions to antituberculosis drugs, current indications of surgical treatment and new drugs under study for the treatment of the disease.

Tratamiento de la tuberculosis drogorresistente en adultos y niños. Revisión narrativa / Treatment of drug-resistant tuberculosis in adults and children. A narrative review

Resumen Desde 2018 han surgido a la luz de la evidencia importantes cambios en el tratamiento de la tuberculosis drogorresistente. El descubrimiento de nuevas drogas antituberculosis, como la bedaquilina y los derivados de nitroimidazopiranos, así como la utilización de drogas repropuestas, llevó a la recomendación de organismos internacionales de nuevos esquemas de tratamiento de la tuberculosis monorresistente y multidro gorresistente que son totalmente orales y así dejan de lado el uso prolongado de inyectables, con su inherente toxicidad e incomodidad. Algunas de las definiciones de tuberculosis drogorresistente han cambiado. También está en revisión el tiempo de su tratamiento y con algunos nuevos esquemas en estudio, como el BpaL (bedaquilina, pretomanid y linezolid), se ha logrado una duración similar a la del tratamiento de la tuberculosis pansensible. En esta revisión bibliográfica narrativa describimos las nuevas definiciones, algunos aspectos diagnósticos básicos, los aspectos farmacológicos y la nueva clasificación de las drogas a utilizar en el tratamiento de la tuberculosis drogorresistente, así como los esquemas actualmente propuestos para tratarla, contextualizados con la realidad nacional. Finalizamos con una breve reseña de los estudios clínicos en curso de nuevos esquemas acortados de tratamiento.

Abstract Since 2018, important changes in the treatment of drug-resistant tuberculosis have been produced in the light of new evidence. The discovery of new anti-tuberculosis drugs, such as bedaquiline and nitroimidazopirane derivatives, as well as the use of repurposed drugs, led to international organizations to recommend new, totally oral, treatment regimens for mono-resistant and multidrug-resistant tuberculosis, leaving aside the prolonged use of injectables, with their inherent toxicity and discomfort. Some definitions of drug-resistant tuberculosis have changed. The duration of treatment is also under review, leading some new regimens under study, such as BPaL (bedaquiline, pretomanid and linezolid), to a duration similar to that for treating susceptible tuberculosis. In this narrative review, we describe the new definitions, some basic diagnostic aspects, the pharmacological aspects, and the new classification of drugs to be used in the treatment of drug-resistant tuberculosis as well as the cur rently proposed schemes to treat it available within the Argentinean context. Finally, we include a brief review of ongoing clinical trials on new shortened treatments.

[Anti-retroviral treatment in patients with AIDS and mycobacterial diseases]. / Tratamiento antirretroviral en pacientes con SIDA y micobacteriosis.

Tuberculosis and other mycobacterial diseases are frequent coinfections in AIDS patients with an increased related mortality. In this review we have updated the treatment of the main mycobacterial diseases (tuberculosis and Mycobacterium avium disease), under the scope of pharmacological interactions between antimycobacterial drugs, specially rifampicin and clarithromycin, and anti-retroviral drugs. Antimycobacterial treatment schemes, their duration, primary and secondary chemoprophylaxis and the optimal time to start the anti-retroviral therapy are analized. Finally, the immnune reconstitution inflammatory syndrome and its treatment are discussed.

A Mycobacterium tuberculosis Dormancy Antigen Differentiates Latently Infected Bacillus Calmette-Guérin-vaccinated Individuals.

IFN-γ release assays (IGRAs) are better indicators of Mycobacterium tuberculosis infection than the tuberculin skin test (TST) in Bacillus Calmette-Guérin (BCG)-vaccinated populations. However, IGRAs do not discriminate active and latent infections (LTBI) and no gold standard for LTBI diagnosis is available. Thus, since improved tests to diagnose M. tuberculosis infection are required, we assessed the efficacy of several M. tuberculosis latency antigens. BCG-vaccinated healthy donors (HD) and tuberculosis (TB) patients were recruited. QuantiFERON-TB Gold In-Tube, TST and clinical data were used to differentiate LTBI. IFN-γ production against CFP-10, ESAT-6, Rv2624c, Rv2626c and Rv2628 antigens was tested in peripheral blood mononuclear cells. LTBI subjects secreted significantly higher IFN-γ levels against Rv2626c than HD. Additionally, Rv2626c peptide pools to which only LTBI responded were identified, and their cumulative IFN-γ response improved LTBI discrimination. Interestingly, whole blood stimulation with Rv2626c allowed the discrimination between active and latent infections, since TB patients did not secrete IFN-γ against Rv2626c, in contrast to CFP-10 + ESAT-6 stimulation that induced IFN-γ response from both LTBI and TB patients. ROC analysis confirmed that Rv2626c discriminated LTBI from HD and TB patients. Therefore, since only LTBI recognizes specific epitopes from Rv2626c, this antigen could improve LTBI diagnosis, even in BCG-vaccinated people.

[Mastitis due to Mycobacterium fortuitum in an HIV negative patient]. / Mastitis por Mycobacterium fortuitum en una paciente HIV negativa.

A case of a 39 year old HIV negative female patient with a Mycobacterium fortuitum mastitis without previous pathogenic history is reported. She was treated on the bases of drug-susceptibility testing and bibliographic empirical evidence with kanamycin, doxicicline, ciprofloxacin and trimetoprim-sulfametoxazol. A complete remission of her lesions was obtained after 15 months of treatment. Lesions due to this rapidly growing mycobacterium, diagnosis and treatment are commented.

IFNG-mediated immune responses enhance autophagy against Mycobacterium tuberculosis antigens in patients with active tuberculosis.

Protective immunity against Mycobacterium tuberculosis (Mtb) requires IFNG. Besides, IFNG-mediated induction of autophagy suppresses survival of virulent Mtb in macrophage cell lines. We investigated the contribution of autophagy to the defense against Mtb antigen (Mtb-Ag) in cells from tuberculosis patients and healthy donors (HD). Patients were classified as high responders (HR) if their T cells produced significant IFNG against Mtb-Ag; and low responders (LR) when patients showed weak or no T cell responses to Mtb-Ag. The highest autophagy levels were detected in HD cells whereas the lowest quantities were observed in LR patients. Interestingly, upon Mtb-Ag stimulation, we detected a positive correlation between IFNG and MAP1LC3B-II/LC3-II levels. Actually, blockage of Mtb-Ag-induced IFNG markedly reduced autophagy in HR patients whereas addition of limited amounts of IFNG significantly increased autophagy in LR patients. Therefore, autophagy collaborates with human immune responses against Mtb in close association with specific IFNG secreted against the pathogen.

[Evaluation of the control measures adopted against an epidemic of AIDS-related multidrug-resistant tuberculosis in a Latin-American hospital]. / Evaluación de las medidas de control adoptadas frente a la epidemia de tuberculosis multirresistente asociada al sida en un hospital hispanoamericano.

BACKGROUND: Since 1992 AIDS-related multidrug-resistant tuberculosis (MDRTB) has been detected among patients admitted to the Hospital Muñiz in Buenos Aires (Argentina). The aim of the present study was to evaluate the effectiveness of the control measures adopted against the nosocomial spread of MDRTB/AIDS, which affected 803 patients between 1992 and 2002. METHODS: An action plan was applied that included bacilloscopy screening on admission, isolation rooms for patients with TB/AIDS, an isolation ward for patients with MDRTB/AIDS, a radiometric method for the diagnosis of multidrug-resistance, a reserve supply of second line drugs, and respiratory protection for health care workers. RESULTS: Between 1995 and 2002, a statistically significant decreasing trend in cases of MDRTB/AIDS and admissions for TB/AIDS was observed (33.9% vs 80.5%). Mortality among patients with MDRTB/AIDS also significantly decreased. Bacilloscopy screening allowed the diagnosis of 63.4% of patients admitted with TB/AIDS. Respiratory isolation facilities and effective treatment of patients with MDRTB diagnosed through the radiometric method were progressively implemented. Admission of patients with AIDS showed no significant variations throughout the study period. The CD41 count of patients requiring admission did not vary significantly. CONCLUSION: The nosocomial epidemic curve of MDRTB in patients with AIDS significantly decreased, despite the persistence of susceptible patients with low CD41 levels. The decreasing tendency of MDRTB/AIDS cases could be attributed to the impact of the control measures implemented.

Estudio de los costos intangibles y de la participación del componente familiar en el costo social de la tuberculosis / Study of the Intangible Costs and the Impact of the Household Component in the Social Cost of Tuberculosis

La tuberculosis (TBC) es uno de los principales problemas de salud pública a nivel mundial. Argentina tiene una elevada tasa de incidencia de 30 por cada 100.000 habitantes. Hay datos sobre los costos directos de la tuberculosis, pero poco se conoce sobre su costo social. OBJETIVOS: explorar la relación entre percepción de enfermedad y costos intangibles de la TBC y medir el impacto del componente hogareño en el costo social de la TBC en el Área Metropolitana de Buenos Aires. Métodos : estudio descriptivo cualitativo y cuantitativo de la pérdida de calidad de vida y del costo social sobre una muestra de 30 pacientes con diagnóstico reciente de TBC y residentes en el Partido de Quilmes y 30 controles sanos. Las variables medidas fueron: costos intangibles o de pérdida de calidad de vida medidos con la encuesta SF-36, costos indirectos o de oportunidad y costos directos por atención de enfermedad. Resultados : para la pérdida de calidad de vida, tanto en casos como en controles, el puntaje promedio fue de 39 puntos en los tópicos generales de salud física y salud mental (escala 0 a 100). El costo social atribuible a la enfermedad alcanzó una suma de AR$ 597.78 por caso para el año 2007, con una participación de casi el 38% de la unidad doméstica. El costo estimado total país ascendió a AR$ 6.207.396,47. Conclusiones : en Argentina, la TBC está claramente vinculada con la vulnerabilidad socioeconómica. En las familias más pobres, la enfermedad impacta fuertemente en la unidad familiar, deteriorando una economía doméstica de por sí crítica

Tuberculosis (TB) is a major public health problem in the world. Argentina has a high rate of incidence of 30 cases per 100,000 inhabitants. There is information about direct costs of TB but little is known aboutits social costs. Objectives: To explore the relation ship between perception of disease and intangible costs; and to measure the impact of the house hold component on the social cost of the disease in the Metropolitan Area of Buenos Aires. Methods: quali-quantitative, descriptive study of the loss of quality of life and the TB social costs on a sample of 30 cases with TB living in Quilmes Partyand 30 controls. The variables included were intangible costs or loss of quality of life assessed through the SF-36survey, indirect or opportunity costs and direct costs of the disease health care. Results: for the loss of quality oflife, so cases as controls, the average score was 39 point sin the general issues of physics and mental health (scale 0 to 100). The social costs attributable to the disease reached a sum of AR$ 597.78 per case, with almost 38% paid from the house hold component. The estimated total country cost was AR$ 6.207.396.47 per year. Conclusions: In Argentina, TB is clearly associated to social-economy vulnerability. In poorest families, the disease strongly impacts on the family unit, worsening the already critic domestic economy

Tratamiento de la tuberculosis: guia practica elaborada por la Seccion Tuberculosis, Asociacion Argentina de Medicina Respiratoria / Tuberculosis treatment: a practical guide elaborated by the Tuberculosis Section, Argentine Association of Respiratory Medicine

La tuberculosis es una enfermedad prevalente en todo el mundo. La emergencia de cepas multirresistentes del Mycobacterium tuberculosis ha incentivado la búsqueda de nuevos fármacos. Existen diversas guías de tratamiento de la enfermedad, internacionales y a nivel programático local. Un grupo de especialistas argentinos elaboró una guía práctica basada en criterios clínicos y en la bibliografía nacional e internacional sobre el tema a través de reuniones de consenso, abarcando tópicos como: fármacos antituberculosos disponibles en la Argentina, modalidades de tratamiento inicial y retratamiento, tratamiento en situaciones especiales, reacciones adversas a fármacos antituberculosos, indicaciones actuales de tratamiento quirúrgico y nuevos fármacos en estudio para el tratamiento de la enfermedad.

Tuberculosis is a worldwide prevalent disease. The emergence of multidrug-resistant strains spurred the search for new drugs. There are several tuberculosis treatment guidelines, international and local in a programmatic approach. An Argentinean specialists panel draw practical guidelines based in clinical criteria and the local and international bibliography through consensus meetings, including issues as: antituberculosis drugs available in Argentina, initial and re-treatement modalities, special situations treatment, adverse reactions to antituberculosis drugs, current indications of surgical treatment and new drugs under study for the treatment of the disease.

Pautas latinoamericanas de diagnóstico y tratamiento de la tuberculosis farmacorresistente / Diagnostic and therapeutic latinamerican guidelines fordrug-resistant tuberculosis

Un panel de expertos latinoamericanos en tuberculosis farmacorresistente estableció por consenso y en un contexto regional un conjunto de lineamientos para su diagnóstico y tratamiento. Las resistencias de Mycobacterium tuberculosis más preocupantes son la tuberculosis multirresistente y la extensamente resistente; las cepas resistentes son seleccionadas mediante el empleo de esquemas terapéuticos erróneos, fármacos de calidad inadecuada, falta de supervisión terapéutica o la combinación de estos tres factores. Su diagnóstico es posible en Latinoamérica a través de la bacteriología convencional y pruebas de sensibilidad para drogas de primera línea y en laboratorios de referencia para segunda línea. El tratamiento puede efectuarse con regímenes estándar o diseñados según pruebas de sensibilidad y se basa en drogas de segunda línea y aquellas de primera línea pasibles de ser utilizadas conformando esquemas de un mínimo de cuatro fármacos que incluyen un inyectable en la fase inicial.

An expert Latin-American consensus panel developeddiagnostic and therapeutic guidelines for drug-resistanttuberculosis in a regional context. The most concerningemerging resistances in M. tuberculosis are multidrug andextensively drug-resistant tuberculosis; drug-resistantstrains are selected through erroneous therapeutic schemes,inadequate quality of drugs and lack of therapeuticsupervision. Diagnosis is possible in Latin-Americanthrough conventional bacteriology, first line drugssusceptibility testing and second line drugs testing inreference laboratories. Treatment can be achieved withstandardized regimens or tailored upon available susceptibilitytesting, with second line drugs and theremaining useful first line drugs, with a minimum of fourdrugs schemes including an injectable drug in the initial phase.