Aplicação de sistemas moleculares na detecção rápida de MDR-TB e XDR-TB

Mycobacterium tuberculosis é o agente etiológico da tuberculose em humanos e segundo as estimativas da Organização Mundial da Saúde, um terço da população mundial está infectada com esta bactéria, calculando-se que no ano de 2008 aproximadamente 9,4 milhões de pessoas contraíram tuberculose activa. Associada a esta tendência, encontra-se o aumento alarmante da incidência de tuberculose resistente aos antibióticos, mais propriamente da tuberculose multirresistente e extensivamente resistente. Nesta Dissertação estudaram-se três sistemas de detecção molecular (INNO-LiPA Rif. TB, Innogenetics, Ghent, Bélgica, MTBDRplus e MTBDRsl, GenoType, GmbH, Nehren, Alemanha), que permitem detectar o complexo M. tuberculosis e as mutações mais comuns associadas à resistência aos antibióticos de primeira e segunda linha. Para o efeito, na primeira parte do trabalho os três sistemas em estudo foram testados em 21 isolados clínicos pertencentes à colecção do Laboratório de Micobactérias do Instituto de Higiene e Medicina Tropical (IHMT, UNL), com o propósito de avaliar a sua capacidade para identificar o complexo M. tuberculosis e detectar mutações ligadas à resistência aos fármacos de primeira e segunda linha. Na segunda parte do trabalho, os sistemas INNO-LiPA Rif. TB e MTBDRplus foram testados em 33 amostras respiratórias com baciloscopia positiva, com o propósito de aferir a “performance” destes sistemas para a detecção directa de tuberculose multirresistente em amostras respiratórias. Na primeira parte do trabalho os três sistemas em estudo apresentaram elevada sensibilidade na identificação do complexo M. tuberculosis em culturas, bem como na detecção de mutações ligadas à resistência aos antibióticos de primeira linha, com excepção do etambutol. No que diz respeito à detecção da resistência aos antibióticos de segunda linha, não foi possível calcular os valores de sensibilidade e especificidade. Na segunda parte do trabalho, o INNO-LiPA Rif. TB demonstrou ser o sistema mais robusto para a análise directa de amostras respiratórias com baciloscopia positiva, para um diagnóstico precoce de tuberculose e detecção de resistência à rifampicina. O MTBDRplus não se mostrou uma alternativa viável ao INNO-LiPA Rif. TB, pois apresentou baixa sensibilidade para a identificação do complexo M. tuberculosis e vários problemas no passo de amplificação. O MTBDRsl não foi testado, por não ter sido detectada nenhuma amostra multirresistente.

Aplicação de sistemas moleculares na detecção rápida de MDR-TB e XDR-TB

Mycobacterium tuberculosis é o agente etiológico da tuberculose em humanos e segundo as estimativas da Organização Mundial da Saúde, um terço da população mundial está infectada com esta bactéria, calculando-se que no ano de 2008 aproximadamente 9,4 milhões de pessoas contraíram tuberculose activa. Associada a esta tendência, encontra-se o aumento alarmante da incidência de tuberculose resistente aos antibióticos, mais propriamente da tuberculose multirresistente e extensivamente resistente. Nesta Dissertação estudaram-se três sistemas de detecção molecular (INNO-LiPA Rif. TB, Innogenetics, Ghent, Bélgica, MTBDRplus e MTBDRsl, GenoType, GmbH, Nehren, Alemanha), que permitem detectar o complexo M. tuberculosis e as mutações mais comuns associadas à resistência aos antibióticos de primeira e segunda linha. Para o efeito, na primeira parte do trabalho os três sistemas em estudo foram testados em 21 isolados clínicos pertencentes à colecção do Laboratório de Micobactérias do Instituto de Higiene e Medicina Tropical (IHMT, UNL), com o propósito de avaliar a sua capacidade para identificar o complexo M. tuberculosis e detectar mutações ligadas à resistência aos fármacos de primeira e segunda linha. Na segunda parte do trabalho, os sistemas INNO-LiPA Rif. TB e MTBDRplus foram testados em 33 amostras respiratórias com baciloscopia positiva, com o propósito de aferir a “performance” destes sistemas para a detecção directa de tuberculose multirresistente em amostras respiratórias. Na primeira parte do trabalho os três sistemas em estudo apresentaram elevada sensibilidade na identificação do complexo M. tuberculosis em culturas, bem como na detecção de mutações ligadas à resistência aos antibióticos de primeira linha, com excepção do etambutol. No que diz respeito à detecção da resistência aos antibióticos de segunda linha, não foi possível calcular os valores de sensibilidade e especificidade. Na segunda parte do trabalho, o INNO-LiPA Rif. TB demonstrou ser o sistema mais robusto para a análise directa de amostras respiratórias com baciloscopia positiva, para um diagnóstico precoce de tuberculose e detecção de resistência à rifampicina. O MTBDRplus não se mostrou uma alternativa viável ao INNO-LiPA Rif. TB, pois apresentou baixa sensibilidade para a identificação do complexo M. tuberculosis e vários problemas no passo de amplificação. O MTBDRsl não foi testado, por não ter sido detectada nenhuma amostra multirresistente.

Efficacy, safety and tolerability of linezolid containing regimens in treating MDR-TB and XDR-TB: systematic review and meta-analysis.

Linezolid is used off-label to treat multidrug-resistant tuberculosis (MDR-TB) in absence of systematic evidence. We performed a systematic review and meta-analysis on efficacy, safety and tolerability of linezolid-containing regimes based on individual data analysis. 12 studies (11 countries from three continents) reporting complete information on safety, tolerability, efficacy of linezolid-containing regimes in treating MDR-TB cases were identified based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Meta-analysis was performed using the individual data of 121 patients with a definite treatment outcome (cure, completion, death or failure). Most MDR-TB cases achieved sputum smear (86 (92.5%) out of 93) and culture (100 (93.5%) out of 107) conversion after treatment with individualised regimens containing linezolid (median (inter-quartile range) times for smear and culture conversions were 43.5 (21-90) and 61 (29-119) days, respectively) and 99 (81.8%) out of 121 patients were successfully treated. No significant differences were detected in the subgroup efficacy analysis (daily linezolid dosage ≤600 mg versus >600 mg). Adverse events were observed in 63 (58.9%) out of 107 patients, of which 54 (68.4%) out of 79 were major adverse events that included anaemia (38.1%), peripheral neuropathy (47.1%), gastro-intestinal disorders (16.7%), optic neuritis (13.2%) and thrombocytopenia (11.8%). The proportion of adverse events was significantly higher when the linezolid daily dosage exceeded 600 mg. The study results suggest an excellent efficacy but also the necessity of caution in the prescription of linezolid.

Effects of GeneXpert MTB/RIF Testing and GxAlert eHealth Platforms on MDR-TB Diagnosis and Linkage to Care in Sofala Province, Mozambique

Thesis (Master's)--University of Washington, 2016-06

Thyroid function in multidrug-resistant tuberculosis patients with or without human immunodeficiency virus (HIV) infection before commencement of MDR-TB drug regimen.

Background: Mycobacterium tuberculosis and human immunodeficiency virus (HIV) are known to cause abnormal thyroid function. There is little information on whether HIV infection aggravates alteration of thyroid function in patients with MDRTB. Objectives: This study was carried out to determine if HIV co-infection alters serum levels of thyroid hormones (T3, T4) and thyroid stimulating hormone (TSH) in patients with MDR-TB patients and to find out the frequency of subclinical thyroid dysfunction before the commencement of MDR-TB therapy. Methods: This observational and cross-sectional study involved all the newly admitted patients in MDR-TB Referral Centre, University College Hospital, Ibadan, Nigeria between July 2010 and December 2014. Serum levels of thyroid stimulating hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3) were determined using ELISA. Results: Enrolled were 115 patients with MDR-TB, out of which 22 (19.13%) had MDR-TB/HIV co-infection. Sick euthyroid syndrome (SES), subclinical hypothyroidism and subclinical hyperthyroidism were observed in 5 (4.35%), 9 (7.83%) and 2 (1.74%) patients respectively. The median level of TSH was insignificantly higher while the median levels of T3 and T4 were insignificantly lower in patients with MDR-TB/HIV co-infection compared with patients with MDRT-TB only. Conclusion: It could be concluded from this study that patients with MDR-TB/HIV co-infection have a similar thyroid function as patients having MDR-TB without HIV infection before commencement of MDR-TB drug regimen. Also, there is a possibility of subclinical thyroid dysfunction in patients with MDR-TB/HIV co-infection even, before the commencement of MDR-TB therapy.

Phenotypic and genotypic variant of MDR-Mycobacterium tuberculosis multiple isolates in the same tuberculosis episode, Rio de Janeiro, Brazil

Assuming that the IS6110-restriction fragment length polymorphism (RFLP) changes at a constant rate of 3.2 years, this methodology was applied to demonstrate, for the first time, variant patterns of Mycobacterium tuberculosis (MTB) in multiple isolates obtained at short time intervals from sputum and blood of an HIV+ patient with multiple admissions to the Emergency Room and to the multidrug-resistant tuberculosis (MDR-TB) Reference Center of a secondary-care hospital in Rio de Janeiro, Brazil. In sputum, the IS6110-RFLP appeared in isolates with two variant patterns with 10 and 13 IS6110 copies. However, blood presented only the pattern corresponding to 10 copies, suggesting compartmentalization. With regard to the exact match of 10 of 13 bands, this may be a subpopulation with the same clonal origin and this may be related to the IS6110 transposition. A susceptibility test demonstrated an MDR profile (INH R, RIF R, SM R, and EMB R), with the sputum isolate also exhibiting EMB S (R = resistant; S = sensitive). A gene mutation confirmed resistance only to streptomycin. There was agreement between the results of the phenotypic test and the clinical response to MDR-TB treatment, suggesting serious implications with regard to treatment administration based exclusively on molecular methods, and calling attention to the fact that more effective control strategies against the emergence of MDR strains must be implemented by the TB control program to prevent transmission of MDR-MTB strains at health facilities in areas highly endemic for TB.

Major challenges in clinical management of TB/HIV co-infected patients in Eastern Europe compared with Western Europe and Latin America.

INTRODUCTION Rates of both TB/HIV co-infection and multi-drug-resistant (MDR) TB are increasing in Eastern Europe (EE). Data on the clinical management of TB/HIV co-infected patients are scarce. Our aim was to study the clinical characteristics of TB/HIV patients in Europe and Latin America (LA) at TB diagnosis, identify factors associated with MDR-TB and assess the activity of initial TB treatment regimens given the results of drug-susceptibility tests (DST). MATERIAL AND METHODS We enrolled 1413 TB/HIV patients from 62 clinics in 19 countries in EE, Western Europe (WE), Southern Europe (SE) and LA from January 2011 to December 2013. Among patients who completed DST within the first month of TB therapy, we linked initial TB treatment regimens to the DST results and calculated the distribution of patients receiving 0, 1, 2, 3 and ≥4 active drugs in each region. Risk factors for MDR-TB were identified in logistic regression models. RESULTS Significant differences were observed between EE (n=844), WE (n=152), SE (n=164) and LA (n=253) for use of combination antiretroviral therapy (cART) at TB diagnosis (17%, 40%, 44% and 35%, p<0.0001), a definite TB diagnosis (culture and/or PCR positive for Mycobacterium tuberculosis; 47%, 71%, 72% and 40%, p<0.0001) and MDR-TB prevalence (34%, 3%, 3% and 11%, p <0.0001 among those with DST results). The history of injecting drug use [adjusted OR (aOR) = 2.03, (95% CI 1.00-4.09)], prior TB treatment (aOR = 3.42, 95% CI 1.88-6.22) and living in EE (aOR = 7.19, 95% CI 3.28-15.78) were associated with MDR-TB. For 569 patients with available DST, the initial TB treatment contained ≥3 active drugs in 64% of patients in EE compared with 90-94% of patients in other regions (Figure 1a). Had the patients received initial therapy with standard therapy [Rifampicin, Isoniazid, Pyrazinamide, Ethambutol (RHZE)], the corresponding proportions would have been 64% vs. 86-97%, respectively (Figure 1b). CONCLUSIONS In EE, TB/HIV patients had poorer exposure to cART, less often a definitive TB diagnosis and more often MDR-TB compared to other parts of Europe and LA. Initial TB therapy in EE was sub-optimal, with less than two-thirds of patients receiving at least three active drugs, and improved compliance with standard RHZE treatment does not seem to be the solution. Improved management of TB/HIV patients requires routine use of DST, initial TB therapy according to prevailing resistance patterns and more widespread use of cART.

Major Challenges in Clinical Management of TB/HIV Coinfected Patients in Eastern Europe Compared with Western Europe and Latin America.

OBJECTIVES Rates of TB/HIV coinfection and multi-drug resistant (MDR)-TB are increasing in Eastern Europe (EE). We aimed to study clinical characteristics, factors associated with MDR-TB and predicted activity of empiric anti-TB treatment at time of TB diagnosis among TB/HIV coinfected patients in EE, Western Europe (WE) and Latin America (LA). DESIGN AND METHODS Between January 1, 2011, and December 31, 2013, 1413 TB/HIV patients (62 clinics in 19 countries in EE, WE, Southern Europe (SE), and LA) were enrolled. RESULTS Significant differences were observed between EE (N = 844), WE (N = 152), SE (N = 164), and LA (N = 253) in the proportion of patients with a definite TB diagnosis (47%, 71%, 72% and 40%, p<0.0001), MDR-TB (40%, 5%, 3% and 15%, p<0.0001), and use of combination antiretroviral therapy (cART) (17%, 40%, 44% and 35%, p<0.0001). Injecting drug use (adjusted OR (aOR) = 2.03 (95% CI 1.00-4.09), prior anti-TB treatment (3.42 (1.88-6.22)), and living in EE (7.19 (3.28-15.78)) were associated with MDR-TB. Among 585 patients with drug susceptibility test (DST) results, the empiric (i.e. without knowledge of the DST results) anti-TB treatment included ≥3 active drugs in 66% of participants in EE compared with 90-96% in other regions (p<0.0001). CONCLUSIONS In EE, TB/HIV patients were less likely to receive a definite TB diagnosis, more likely to house MDR-TB and commonly received empiric anti-TB treatment with reduced activity. Improved management of TB/HIV patients in EE requires better access to TB diagnostics including DSTs, empiric anti-TB therapy directed at both susceptible and MDR-TB, and more widespread use of cART.

Emergence of multidrug-resistant tuberculosis in a community-based directly observed treatment programme in rural South Africa

OBJECTIVE: Although little studied in developing countries, multidrug-resistant tuberculosis (MDR-TB) is considered a major threat. We report the molecular epidemiology, clinical features and outcome of an emerging MDR-TB epidemic. METHODS: In 1996 all tuberculosis suspects in the rural Hlabisa district, South Africa, had sputum cultured, and drug susceptibility patterns of mycobacterial isolates were determined. Isolates with MDR-TB (resistant to both isoniazid and rifampicin) were DNA fingerprinted by restriction fragment length polymorphism (RFLP) using IS6110 and polymorphic guanine-cytosine-rich sequence-based (PGRS) probes. Patients with MDR-TB were traced to determine outcome. Data were compared with results from a survey of drug susceptibility done in 1994. RESULTS: The rate of MDR-TB among smear-positive patients increased six-fold from 0.36% (1/275) in 1994 to 2.3% (13/561) in 1996 (P = 0.04). A further eight smear-negative cases were identified in 1996 from culture, six of whom had not been diagnosed with tuberculosis. MDR disease was clinically suspected in only five of the 21 cases (24%). Prevalence of primary and acquired MDR-TB was 1.8% and 4.1%, respectively. Twelve MDR-TB cases (67%) were in five RFLP-defined clusters. Among 20 traced patients, 10 (50%) had died, five had active disease (25%) and five (25%) were apparently cured. CONCLUSIONS: The rate of MDR-TB has risen rapidly in Hlabisa, apparently due to both reactivation disease and recent transmission. Many patients were not diagnosed with tuberculosis and many were not suspected of drug-resistant disease, and outcome was poor.

Drug-resistant tuberculosis in six hospitals in Rio de Janeiro, Brazil

SETTING: Tuberculosis (TB) drug resistance survey in six hospitals in Rio de Janeiro, Brazil. OBJECTIVE: To estimate resistance to at least one drug (DR) and multidrug resistance (MDR) and identify associated factors. DESIGN: One-year cross-sectional survey. Hospitals were included as a convenience sample. RESULTS: Of 595 patients investigated, 156 (26.2%) had previously undergone anti-tuberculosis treatment, 433 (72.8%) were not previously treated and information on the remaining 6 was not available. Overall, DR and MDR rates were high, at respectively 102 (17.1%, 95%CI 14.3-20.5) and 44 (7.4%, 95%CI 5.5-9.9) cases. Among individuals not previously treated, 17 had MDR (3.9%, 95%CI 2.4-6.3) and diagnosis in a TB reference hospital was independently associated with MDR (prevalence ratio [PR] 3.3, 95%CI 1.2-8.7) after multivariate analysis. Among previously treated individuals, 27 had MDR (17.3%, 95%CI 11.7-24.2). MDR-TB was independently associated with diagnosis in a TB reference hospital (PR 3.6, 95%CI 1.5-8.7), male sex (PR 2.3,95%CI 1.2-4.4) and dyspnoea (PR 0.3, 95%CI 0.1-0.7). CONCLUSION: We found high levels of DR- and MDR-TB. Our study design did not permit us to determine the contribution of community versus nosocomial transmission. Further studies are needed to establish this. Nevertheless, hospitals should be recognised as a potential source of transmission of resistant TB strains and urgent measures to avoid nosocomial TB transmission should be taken.

Tuberculose na população privada de liberdade: características clínicas e epidemiológicas relacionadas à doença

Introdução: Há cerca de duas décadas, a tuberculose (TB) foi considerada pela Organização Mundial de Saúde (OMS) como uma doença em estado de emergência em todo o mundo. Atualmente, apesar de todas as ações de controle da doença, ainda trata-se de um importante problema de saúde pública, apresentando forte relação com questões socioeconômicas, o que acarreta no maior adoecimento em grupos específicos, tais como a população privada de liberdade. Os dados de tuberculose em populações vulneráveis podem atingir índices ainda mais altos e por isso preocupante. Objetivos: Analisar as características clínicas e epidemiológicas associadas com os desfechos do tratamento da tuberculose na população privada de liberdade do Brasil, registrado no Sistema de Informação de Agravos de Notificação (SINAN), de 2007 a 2011; conhecer a taxa de incidência e de mortalidade por tuberculose na população privada de liberdade do Espírito Santo, de julho de 2009 a julho de 2010; e identificar as características clínicas e epidemiológicas dos casos diagnosticados de tuberculose na população privada de liberdade do Espírito Santo, de julho de 2009 a julho de 2010. Métodos: A população do estudo consistiu em presos diagnosticados com tuberculose identificados através do SINAN, entre janeiro de 2007 e dezembro de 2011 e dos casos diagnosticados de tuberculose na população prisional do Espírito Santo no período de 1º de julho de 2009 a 30 de junho de 2010. O teste de qui-quadrado de Pearson e o modelo de regressão polinomial foram utilizados na analise, além de estatística descritiva, por meio de tabelas e gráficos. Resultados: Em relação pacientes com TB na população privada de liberdade do Brasil, nota-se que os presos que abandonaram o tratamento eram mais jovens (P <0,001), com menor escolaridade (P <0,001) e maior probabilidade de alcoolismo (P < 0,001), eram mais propensos a ter TB recorrente ou recidiva (P < 0,001) e eles não estavam sob tratamento diretamente observado (TDO) (P < 0,001), comparados com aqueles que completaram o tratamento da tuberculose. Aqueles que morreram de tuberculose tendem a ter idade ⩾ 43 anos (P < 0,001) e alcoolistas (P < 0,001), também eram mais propensos a tipo de tratamento desconhecido (P <0,001) e apresentar tuberculose pulmonar e tuberculose extrapulmonar (TBEP). Presos que desenvolveram tuberculose multidroga resistente (TB-MDR) foram mais propensos a 9 experiência de recorrência de TB, retorno após abandono e transferência de local de tratamento. Além disso, observou-se 167 casos de tuberculose (taxa de incidência de 1962,6 por 100 mil presos) no Espírito Santo. O sexo masculino apresentou maior número de pacientes, assim como a faixa etária de 25 a 36 anos e a forma clínica pulmonar. Destaca-se que 109 (65,3%) pacientes tiveram alta por cura, ocorrendo dois óbitos durante o período, sendo a taxa de mortalidade por tuberculose de 11,7 por 100 mil presos. A maior incidência da tuberculose foi em pacientes localizados nas unidades prisionais da Região Metropolitana e um pequeno número de casos ocorreu em outros locais externos às unidades prisionais. Conclusão: Nossos resultados destacam a necessidade de melhorar as políticas de controle da TB nas penitenciárias, bem como os desfechos do tratamento de presos a fim de impedir a transmissão para outros presos, seus familiares e profissionais de saúde.

Investigation and Control of a Large Outbreak of Multi-Drug Resistant Tuberculosis at a Central Lisbon Hospital

An increase in the number of new cases of tuberculosis (TB) combined with poor clinical outcome was identified among HIV-infected injecting drug users attending a large HIV unit in central Lisbon. A retrospective epidemiological and laboratory study was conducted to review all newly diagnosed cases of TB from 1995 to 1996 in the HIV unit. Results showed that from 1995 to 1996, 63% (109/173) of the Mycobacterium tuberculosis isolates from HIV-infected patients were resistant to one or more anti-tuberculosis drugs; 89% (95) of these were multidrug-resistant, i.e., resistant to at least isoniazid and rifampicin. Eighty percent of the multidrug-resistant strains (MDR) available for restriction fragment length polymorphism (RFLP) DNA fingerprinting clustered into one of two large clusters. Epidemiological data support the conclusion that the transmission of MDR-TB occurred among HIV-infected injecting drug users exposed to infectious TB cases on open wards in the HIV unit. Improved infection control measures on the HIV unit and the use of empirical therapy with six drugs once patients were suspected to have TB, reduced the incidence of MDR-TB from 42% of TB cases in 1996 to 11% in 1999.

Gold nanoprobes for the detection of mutations associated with antibiotic resistance in Mycobacterium tuberculosis complex

Dissertação para obtenção do Grau de Mestre em Genética Molecular e Biomedicina

Antimycobacterial neolignans isolated from Aristolochia taliscana

Tuberculosis (TB - Mycobacterium tuberculosis) is an ancient infectious disease that has appeared once again as a serious worldwide health problem and now comprises the second leading cause of death resulting from a single infection. The prevalence of multidrug resistance (MDR) TB is increasing and therapeutic options for treatment are not always accessible; in fact, some patients do not respond to the available drugs. Therefore, there is an urgent need to develop novel anti-TB agents. The aim of the present study was to screen extracts of Aristolochia taliscana, a plant used in traditional Mexican medicine to treat cough and snake bites, for antimycobacterial activity. The hexanic extract of A. taliscana was tested by microdilution alamar blue assay against Mycobacterium strains and bioguided fractionation led to the isolation of the neolignans licarin A, licarin B and eupomatenoid-7, all of which had antimycobacterial activity. Licarin A was the most active compound, with minimum inhibitory concentrations of 3.12-12.5 μg/mL against the following M. tuberculosis strains: H37Rv, four mono-resistant H37Rv variants and 12 clinical MDR isolates, as well as against five non-tuberculous mycobacteria (NTM) strains. In conclusion, licarin A represents a potentially active anti-TB agent to treat MDR M. tuberculosis and NTM strains.

Clinical data and molecular analysis of Mycobacterium tuberculosis isolates from drug-resistant tuberculosis patients in Goiás, Brazil

Drug resistance is one of the major concerns regarding tuberculosis (TB) infection worldwide because it hampers control of the disease. Understanding the underlying mechanisms responsible for drug resistance development is of the highest importance. To investigate clinical data from drug-resistant TB patients at the Tropical Diseases Hospital, Goiás (GO), Brazil and to evaluate the molecular basis of rifampin (R) and isoniazid (H) resistance in Mycobacterium tuberculosis. Drug susceptibility testing was performed on 124 isolates from 100 patients and 24 isolates displayed resistance to R and/or H. Molecular analysis of drug resistance was performed by partial sequencing of the rpoB and katGgenes and analysis of the inhA promoter region. Similarity analysis of isolates was performed by 15 loci mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) typing. The molecular basis of drug resistance among the 24 isolates from 16 patients was confirmed in 18 isolates. Different susceptibility profiles among the isolates from the same individual were observed in five patients; using MIRU-VNTR, we have shown that those isolates were not genetically identical, with differences in one to three loci within the 15 analysed loci. Drug-resistant TB in GO is caused by M. tuberculosis strains with mutations in previously described sites of known genes and some patients harbour a mixed phenotype infection as a consequence of a single infective event; however, further and broader investigations are needed to support our findings.