RESUMO
Introduction Drug-resistant tuberculosis (DR-TB) is a major concern to effective control of tuberculosis (TB) in India and the likelihood of drug resistance increases with repeated exposure to anti-TB drugs. India has emerged as one of the leading contributors of DR-TB in the world posing a major threat to TB control. In the current study, we aim to find the burden and factors associated with drug resistance in previously treated pulmonary TB patients. Methods A cross-sectional study was conducted among 230 previously treated pulmonary TB patients registered with Directly Observed Treatment, Short-course (DOTS) centers under Nehru Nagar Chest clinic in Delhi, India. The participants were selected consecutively as they registered with the chest clinic. A predesigned, pretested, semi-structured questionnaire in the Hindi language used to collect socio-demographic data and factors associated with the development of drug resistance. Physical examination of all the participants was done (height, weight, pallor). Data were analyzed using SPSS version 21. Binary logistic regression analysis was used to identify independent risk factors of drug resistance. Results Of 230 previously treated pulmonary TB patients, 80 (34.8% (95% CI:28.7-40.9%)) were drug-resistant. Age (p=0.021), ever consumption of alcohol (p= 0.001), pallor (p=0.06), BMI (p=0.028), fasting blood sugar (p=0.001), treatment failure (p=0.005) and the number of prior courses of anti-tuberculosis treatment (ATT) taken (p=0.004) were significantly associated with drug resistance. On applying binary logistic regression analysis, independently associated factors with drug resistance were ever consumption of alcohol, pallor, high fasting blood sugar level, previous treatment failure patients and the number of prior courses of ATT (p<0.05). Conclusion The findings of this study revealed that patients who had pallor, high fasting blood sugar, treatment failure and who had two or more prior courses of ATT were more likely to have DR-TB. Identifying the risk factors for drug-resistant TB is essential in facilitating the government to draw public health interventions. Further research is warranted to explore the causal associations.
RESUMO
Replacement of the toxic heavy element lead in metal halide perovskites has been attracting a great interest because the high toxicity and poor air stability are two of the major barriers for their widespread utilization. Recently, mixed-cation double perovskite halides, also known as elpasolites, were proposed as an alternative lead-free candidate for the design of nontoxic perovskite solar cells. Herein, we report a new nontoxic and air stable lead-free all-inorganic semiconductor Rb4Ag2BiBr9 prepared using the mixed-cation approach; however, Rb4Ag2BiBr9 adopts a new structure type (Pearson's code oP32) featuring BiBr6 octahedra and AgBr5 square pyramids that share common edges and corners to form a unique 2D layered non-perovskite structure. Rb4Ag2BiBr9 is also demonstrated to be thermally stable with the measured onset decomposition temperature of To = 520 °C. Optical absorption measurements and density functional theory calculations suggest a nearly direct band gap for Rb4Ag2BiBr9. Room temperature photoluminescence (PL) measurements show a broadband weak emission. Further, temperature-dependent and power-dependent PL measurements show a strong competition between multiple emission centers and suggest the coexistence of defect-bound excitons and self-trapped excitons in Rb4Ag2BiBr9.