High frequency of resistance to the drugs isoniazid and rifampicin among tuberculosis cases in the city of Cabo de Santo Agostinho, an urban area in Northeastern Brazil

Epidemiology of multi-drug resistant Tuberculosis in the western region of Kenya

Multidrug-resistant tuberculosis (TB) (MDR-TB), or TB that is simultaneously resistant to both isoniazid (INH) and rifampicin (RIF), is a barrier to successful TB control and treatment. Stratified data on MDR-TB, particularly in the high-burden western Kenya region, remain unknown. This data is important to monitor the efficacy of TB control and treatment efforts. Herein, we determined the molecular epidemiology of drug-resistant TB and associated risk factors in western Kenya. This was a non-experimental, population-based, cross-sectional study conducted between January and August 2018. Morning sputum samples of individuals suspected of pulmonary TB were collected, processed, and screened for Mycobacterium tuberculosis (Mtb) and drug resistance using line probe assay (LPA) and Mycobacterium growth indicator tubes (MGIT) culture. MGIT-positive samples were cultured on brain heart infusion (BHII) agar media, and the presence of Mtb was validated using Immunochromatographic assay (ICA). Drug sensitivity was performed on MGIT and ICA-positive but BHI-negative samples. Statistical significance was set at P < 0.05. Of the 622 Mtb isolates, 536 (86.2%) were susceptible to RIF and INH. The rest, 86 (13.83%), were resistant to either drugs or both. A two-sample proportional equality test revealed that the MDR-TB prevalence in western Kenya (5%) did not vary significantly from the global MDR-TB estimate (3.9%) (P = 0.196). Men comprised the majority of susceptible and resistant TB (75.9% and 77.4%%, respectively). Also, compared with healthy individuals, the prevalence of HIV was significantly higher in MDR-TB patients (35.9% vs 5.6%). Finally, TB prevalence was highest in individuals aged 25-44 years, who accounted for 58.4% of the total TB cases. Evidently, the prevalence of MDRTB in western Kenya is high. Particular attention should be paid to men, young adults, and those with HIV, who bear the greatest burden of resistant TB. Overall, there is a need to refine TB control and treatment programs in the region to yield better outcomes.

Primary and acquired multidrug-resistant tuberculosis: Predictive factors for unfavorable treatment outcomes in Rio de Janeiro, 2000-2016

Objective

To identify clinical and demographic factors associated with unfavorable treatment outcomes in patients with primary and acquired multidrug-resistant tuberculosis (MDR-TB) in Rio de Janeiro State.

Methods

Retrospective cohort study using data on 2 269 MDR-TB cases in 2000–2016. Factors associated with unsuccessful, loss to follow-up, and death outcomes in patients with primary and acquired resistance were investigated with bivariate and multivariate regression.

Results

Primary resistance was 14.7% among MDR-TB cases. The unfavorable outcomes proportion was 30.3% in the primary resistance group and 46.7% in the acquired resistance group. There were significant differences in demographic and clinical characteristics between the two groups. Proportionally, the group with primary resistance had more cases among women (46.4% vs. 33.5% in the acquired resistance group), Caucasians (47.3% and 34%), and those with ≥8 years of schooling (37.7% and 27.4%). Extensively drug-resistant TB patients had 12.2-fold higher odds of unsuccessful outcome than MDR-TB patients, and comorbidities had 2-fold higher odds in the primary resistance group. Extensively drug-resistant TB had 5.43-fold higher odds in the acquired MDR-TB group. Bilateral disease and <8 years of schooling were associated with unsuccessful outcome in both groups. Being an inmate had 8-fold higher odds of loss to follow-up in the primary resistance group. Culture conversion by the sixth month was a protective factor for all outcomes.

Conclusions

Primary resistance cases of MDR-TB constitute a different transmission reservoir, which is related to other chronic diseases associated with higher acquisition of TB. The poor results observed in Rio de Janeiro State can contribute to increasing the transmission of primary MDR-TB, thus favoring drug resistance.

Evaluation of the impact that the changes in tuberculosis treatment implemented in Brazil in 2009 have had on disease control in the country

Objective:

To analyze the impact that the 2009 changes in tuberculosis treatment in Brazil had on the rates of cure, tuberculosis recurrence, mortality, treatment abandonment, and multidrug-resistant tuberculosis (MDR-TB).

Methods:

An ordinary least squares regression model was used in order to perform an interrupted time series analysis of secondary data collected from the Brazilian Tuberculosis Case Registry Database for the period between January of 2003 and December of 2014.

Results:

The 2009 changes in tuberculosis treatment in Brazil were found to have no association with reductions in the total number of cases (β = 2.17; 95% CI: −3.80 to 8.14; p = 0.47) and in the number of new cases (β = −0.97; 95% CI: −5.89 to 3.94; p = 0.70), as well as having no association with treatment abandonment rates (β = 0.40; 95% CI: −1.12 to 1.93; p = 0.60). The changes in tuberculosis treatment also showed a trend toward an association with decreased cure rates (β = −4.14; 95% CI: −8.63 to 0.34; p = 0.07), as well as an association with increased mortality from pulmonary tuberculosis (β = 0.77; 95% CI: 0.16 to 1.38; p = 0.01). Although there was a significant increase in MDR-TB before and after the changes (p < 0.0001), there was no association between the intervention (i.e., the changes in tuberculosis treatment) and the increase in MDR-TB cases.

Conclusions:

The changes in tuberculosis treatment were unable to contain the decrease in cure rates, the increase in treatment abandonment rates, and the increase in MDR-TB rates, being associated with increased mortality from pulmonary tuberculosis during the study period.

Keywords: Tuberculosis, pulmonary/epidemiology; Tuberculosis, pulmonary/drug therapy; Tuberculosis, pulmonary/mortality; Interrupted time series analysis; Drug resistance, multiple; Drug compounding.

Adaptive gene profiling of Mycobacterium tuberculosis during sub-lethal kanamycin exposure

Resistance to anti-tuberculosis drugs is a formidable obstacle to effective tuberculosis (TB) treatment and prevention globally. New forms of multidrug, extensive drug and total drug resistance Mycobacterium tuberculosis (Mtb) causing a serious threat to human as well as animal's population. Mtb shows diverse adaptability under stress conditions especially antibiotic treatment, however underlying physiological mechanism remained elusive. In present study, we investigated Mtb's response and adaptation with reference to gene expression during sub-lethal kanamycin exposure. Mtb were cultured under sub-lethal drug and control conditions, where half were sub-cultured every 3-days to observe serial adaptation under same conditions and the remaining were subjected to RNA-seq. We identified 98 up-regulated and 198 down-regulated responsive genes compared to control through differential analysis, of which Ra1750 and Ra3160 were the most responsive genes. In adaptive analysis, we found Ra1750, Ra3160, Ra3161, Ra3893 and Ra2492 up-regulation at early stage and gradually showed low expression levels at the later stages of drug exposure. The adaptive expression of Ra1750, Ra3160 and Ra3161 were further confirmed by real time qPCR. These results suggested that these genes contributed in Mtb's physiological adaptation during sub-lethal kanamycin exposure. Our findings may aid to edify these potential targets for drug development against drug resistance tuberculosis.

Mycobacterium tuberculosis resistance to antituberculosis drugs in Mozambique

OBJECTIVE:

To determine the drug resistance profile of Mycobacterium tuberculosis in Mozambique.

METHODS:

We analyzed secondary data from the National Tuberculosis Referral Laboratory, in the city of Maputo, Mozambique, and from the Beira Regional Tuberculosis Referral Laboratory, in the city of Beira, Mozambique. The data were based on culture-positive samples submitted to first-line drug susceptibility testing (DST) between January and December of 2011. We attempted to determine whether the frequency of DST positivity was associated with patient type or provenance.

RESULTS:

During the study period, 641 strains were isolated in culture and submitted to DST. We found that 374 (58.3%) were resistant to at least one antituberculosis drug and 280 (43.7%) were resistant to multiple antituberculosis drugs. Of the 280 multidrug-resistant tuberculosis cases, 184 (65.7%) were in previously treated patients, most of whom were from southern Mozambique. Two (0.71%) of the cases of multidrug-resistant tuberculosis were confirmed to be cases of extensively drug-resistant tuberculosis. Multidrug-resistant tuberculosis was most common in males, particularly those in the 21-40 year age bracket.

CONCLUSIONS:

M. tuberculosis resistance to antituberculosis drugs is high in Mozambique, especially in previously treated patients. The frequency of M. tuberculosis strains that were resistant to isoniazid, rifampin, and streptomycin in combination was found to be high, particularly in samples from previously treated patients.

Prevalência de resistência primária em pacientes com tuberculose pulmonar sem fatores de risco conhecidos para resistência primária

OBJETIVO: Estimar a prevalência de resistência primária aos medicamentos do esquema básico de tratamento antituberculose em pacientes com tuberculose pulmonar virgens de tratamento sem fatores de risco conhecidos para resistência primária, e identificar os possíveis fatores associados à resistência medicamentosa. MÉTODOS: Estudo transversal exploratório com a análise de prontuários de pacientes que participaram de dois ensaios clínicos de tuberculose sensível entre 1&º de novembro de 2004 e 31 de março de 2011 no Ambulatório Prof. Newton Bethlem do Instituto de Doenças do Tórax da Universidade Federal do Rio de Janeiro, Rio de Janeiro (RJ). Os critérios de inclusão foram ter idade > 18 anos, ter pesquisa direta de BAAR positiva na primeira amostra de escarro, ter cultura positiva para Mycobacterium tuberculosis, ter realizado testes de sensibilidade aos fármacos, ser virgem de tratamento para tuberculose e não ter história de prisão, hospitalização ou contato com caso de tuberculose resistente. RESULTADOS: Foram incluídos 209 pacientes. A prevalência de resistência primária geral foi de 16,3%. A prevalência geral de resistência à isoniazida e à estreptomicina foi, respectivamente, 9,6% e 9,1%, enquanto a prevalência de monorresistência à isoniazida e à estreptomicina foi de, respectivamente, 5,8% e 6,8%. A prevalência de resistência a dois ou mais fármacos foi de 3,8%, e a prevalência de tuberculose multirresistente foi de 0,5%. Não foram observadas associações estatisticamente significativas entre as variáveis estudadas e resultados do teste de sensibilidade aos fármacos. CONCLUSÕES: Na amostra estudada, a prevalência de resistência primária foi elevada apesar da ausência de fatores de risco conhecidos.

Role of TNF-Alpha, IFN-Gamma, and IL-10 in the Development of Pulmonary Tuberculosis

Host immune response against Mycobacterium tuberculosis is mediated by cellular immunity, in which cytokines and Th1 cells play a critical role. In the process of control of the infection by mycobacteria, TNF-alpha seems to have a primordial function. This cytokine acts in synergy with IFN-gamma, stimulating the production of reactive nitrogen intermediates (RNIs), thus mediating the tuberculostatic function of macrophages, and also stimulating the migration of immune cells to the infection site, contributing to granuloma formation, which controls the disease progression. IFN-gamma is the main cytokine involved in the immune response against mycobacteria, and its major function is the activation of macrophages, allowing them to exert its microbicidal role functions. Different from TNF-alpha and IFN-gamma, IL-10 is considered primarily an inhibitory cytokine, important to an adequate balance between inflammatory and immunopathologic responses. The increase in IL-10 levels seems to support the survival of mycobacteria in the host. Although there is not yet conclusive studies concerning a clear dichotomy between Th1 and Th2 responses, involving protective immunity and susceptibility to the disease, respectively, we can suggest that the knowledge about this responses based on the prevailing cytokine profile can help to elucidate the immune response related to the protection against M. tuberculosis.

Successes and failures in the control of infectious diseases in Brazil: social and environmental context, policies, interventions, and research needs

Despite pronounced reductions in the number of deaths due to infectious diseases over the past six decades, infectious diseases are still a public health problem in Brazil. In this report, we discuss the major successes and failures in the control of infectious diseases in Brazil, and identify research needs and policies to further improve control or interrupt transmission. Control of diseases such as cholera, Chagas disease, and those preventable by vaccination has been successful through efficient public policies and concerted efforts from different levels of government and civil society. For these diseases, policies dealt with key determinants (eg, the quality of water and basic sanitation, vector control), provided access to preventive resources (such as vaccines), and successfully integrated health policies with broader social policies. Diseases for which control has failed (such as dengue fever and visceral leishmaniasis) are vector-borne diseases with changing epidemiological profiles and major difficulties in treatment (in the case of dengue fever, no treatment is available). Diseases for which control has been partly successful have complex transmission patterns related to adverse environmental, social, economic, or unknown determinants; are sometimes transmitted by insect vectors that are difficult to control; and are mostly chronic diseases with long infectious periods that require lengthy periods of treatment.

Risk factors for drug resistance in pulmonary tuberculosis inpatients

OBJECTIVE

To analyze risk factors for drug resistance in pulmonary tuberculosis (PTB) inpatients.

METHODS

Medical records of PTB inpatients in Chengdu Tuberculosis Hospital (CTH) from 2005 to 2007 were investigated retrospectively. A logistic regression model was used to analyze data.

RESULTS

A total of 330 records were included in the analysis. A history of tuberculosis treatment was associated with drug resistance with odds ratio (OR) 16.79 and 95% confidence interval (95% CI) [10.14, 27.80] for all patients. Among new patients, the significant risk factor was duration of illness (OR 0.27, 95% CI [0.16, 0.46]), and for previously treated patients, risk factors included age (OR 0.96, 95% CI [0.93, 0.99]), improper initial chemotherapy (OR 3.85, 95% CI [1.59, 10.00]), and improper handling by medical staff (OR 3.44, 95% CI [1.32, 8.96]).

CONCLUSIONS

A history of drug treatment is associated with drug resistance among PTB inpatients. Initial resistance becomes increasingly serious till 2007. To minimize the development of resistance, more personalized treatment and supervision should be used, and better training for medical staff is needed.

Evaluation of memory immune response to mycobacterium extract among household contact of tuberculosis cases

The human immune response to tuberculosis (TB) is especially mediated by T CD4(+)lymphocytes. However, more studies are needed in order to understand the exact role of each cytokine in the mechanisms for cures. In this article, our aim was to analyze the production of TNF-alpha, IL-10, and IFN-gamma in peripheral blood mononuclear cells (PBMCs) among the household contacts of common primary TB cases, with or without histories of active TB infection, who were negative to parasitological and HIV tests. In order to characterize the cytokine production, PBMCs from these groups were stimulated with whole-protein extract of M. tuberculosis (WPE) antigen (rAgTb) for 24 and 48 hr. The culture supernatants were collected and IFN-gamma, TNF-alpha, and IL-10 were assayed using capture ELISA. There were no statistical differences between primary TB cases and their household contacts with or without previous histories of lung TB. Our results suggest that T memory cells, T regulatory cells, and the Th1/Th2 dichotomy may be responsible for the results described in this article. Further studies are currently underway.