Isoniazid-resistant tuberculosis in Iran: A systematic review

Drug resistance and its risk factors among extrapulmonary tuberculosis in Ethiopia: A systematic review and meta-analysis

Background

Drug-resistant tuberculosis and extrapulmonary tuberculosis are the world major public health issues. Although some primary studies have been reported on the burden of drug-resistant tuberculosis in extrapulmonary tuberculosis patients in Ethiopia, there is no systematic review and meta-analysis that attempt to summarize the available literature. Thus, we aimed to estimates the prevalence of drug-resistance in extrapulmonary tuberculosis patients and summarize the risk factors associated with the occurrence of extrapulmonary tuberculosis in Ethiopia.

Methods

We conducted a systematic review of the published primary studies on extrapulmonary drug-resistant tuberculosis in Ethiopia.

Results

Eight observational studies were included in this review from different regions of Ethiopia. The overall pooled prevalence of rifampicin resistance was 6% (95% CI 0.03–0.10), while isoniazid resistance was 7% (95% CI 0.03–0.12). The pooled prevalence of multidrug-resistant tuberculosis was 4% (95% CI 0.01–0.07). Previous tuberculosis treatment history and male gender are frequently reported risk factors for developing drug-resistant tuberculosis in extrapulmonary tuberculosis patients.

Conclusion

The current review has identified a high proportion of resistance to rifampicin, isoniazid, and multidrug-resistant tuberculosis in patients with extrapulmonary tuberculosis in Ethiopia. Clinicians should request drug susceptibility testing for all patients with presumptive extrapulmonary tuberculosis to detect drug-resistance.

Tuberculosis in Iran: a historical overview from al-Tabari, Rhazes, Avicenna and Jorjani to Abolhassan Ziyā-Zarifi. Old and new pioneers in the fight against tuberculosis: challenges, pitfalls and hopes

Tuberculosis is a serious respiratory infectious disease, caused by Mycobacterium tuberculosis bacteria. It has always represented a permanent, serious public health challenge over the course of human history, because of its severe epidemiological, clinical and societal implications. The present review aims at over-viewing the contributions of the Iranian medicine to the control, management and treatment of tuberculosis, from the glorious past of the eighth-ninth centuries to the present, from Ali Abu al-Hasan Ahmad ibn Sahl-e Rabban al-Tabari to Rhazes, Avicenna, Jorjani and Abolhassan Ziyā-Zarifi. However, despite the efforts, tuberculosis and, in particular, multidrug-resistant tuberculosis still represent a great public health concern in Iran. On the other hand, this country can capitalize on its millennial, incredibly rich story of major achievements in the battle against tuberculosis to develop and implement ad hoc public health programs for the control of the disorder, including targeted and specialized interventions.

Modeling the structural origins of drug resistance to isoniazid via key mutations in Mycobacterium tuberculosis catalase-peroxidase, KatG

WHO reported 10.4 million new tuberculosis (TB) cases and 1.8 million deaths in 2015, making M. tuberculosis the most successful human pathogen with highest mortality among infectious diseases [1,2]. Drug-resistant TB is a major threat to global TB control [2,3]. Recently Torres et al. [4] identified 14 novel substitutions in M. tuberculosis-KatG (the enzyme associated with resistance to isoniazid-an important first-line anti-TB drug) and demonstrated that 12 of the 14 can cause INH-resistance in M. smegmatis. This study presents an in silico structure-based analysis of these 14 amino acid substitutions using homology models and x-ray crystal structures (when available) in M. tuberculosis. Our models demonstrate that several of these mutations cluster around three openings in the KatG tertiary structure which appear to initiate channels to the heme group at the catalytic center of the enzyme. We studied the effects of these mutations on the tertiary structure of KatG, focusing on conformational changes in the three channels in the protein structure. Our results suggest that the 14 novel mutations sufficiently restrict one or more of these access channels, thus potentially preventing INH from reaching the catalytic heme. These observations provide valuable insights into the structure-based origins of INH resistance and provide testable hypotheses for future experimental studies.

The reliability of rifampicin resistance as a proxy for multidrug-resistant tuberculosis: a systematic review of studies from Iran

In Iran, patients showing rifampicin (RIF) resistance detected by the Xpert® MTB/RIF assay are considered as candidates for multidrug-resistant tuberculosis (MDR-TB) treatment. Despite the fact that RIF resistance has been used as a proxy for MDR-TB, little is known about the proportion of isoniazid (INH) resistance patterns in RIF-resistant TB. We systematically searched MEDLINE, Embase, and other databases up to March 2017 for studies addressing the proportion of INH resistance patterns in RIF-resistant TB in Iran. The data were pooled using a random effects model. Heterogeneity was assessed using Cochran's Q and I² statistics. A total of 11 articles met the eligibility criteria. Data analysis demonstrated that 33.3% of RIF-resistant isolates from new TB cases and 14.8% of RIF-resistant isolates from previously treated cases did not display resistance to INH. The relatively high proportion of INH susceptibility among isolates with RIF resistance indicated that RIF resistance may no longer predict MDR-TB in Iran. Therefore, the detection of RIF resistance by the Xpert MTB/RIF assay will require complementary detection of INH resistance by other drug susceptibility testing (DST) methods in order to establish the diagnosis of MDR-TB.

Primary ethambutol resistance among Iranian pulmonary tuberculosis patients: a systematic review

INTRODUCTION

Ethambutol (EMB) is an anti-mycobacterial agent that is most commonly used in combination with other anti-tuberculosis (TB) drugs in the treatment of TB. Studies have shown that primary resistance rates of Mycobacterium tuberculosis to EMB vary widely, that is, from 1% to as high as 14%. In this study, we aimed to determine the exact prevalence of primary EMB resistance among pulmonary TB cases.

METHODS

Several databases, including Medline, Embase, and Iranian databases, were searched from March 2000 to January 2016 to identify studies addressing EMB-resistant TB in Iran. Comprehensive meta-analysis (V2.2, Biostat) software was used to analyze the data.

RESULTS

Of the 112 records identified from the databases, 10 studies fulfilled the eligibility criteria. The pooled prevalence of primary EMB-resistant TB was estimated at 4.2% [95% confidence interval (CI) 1.8-9.0]. No evidence of publication bias was observed among the included studies (p = 0.4 for Begg rank correlation analysis; p = 0.2 for Egger weighted regression analysis).

CONCLUSION

Results of systematic review and meta-analyses indicated that effective strategies to minimize the acquired drug resistance, to improve the drug susceptibility testing (DST) capability, and to control the transmission of resistance should be attached importance for control of TB in Iran.