Detection of Mycobacterium kansasii using a combination of loop-mediated isothermal amplification (LAMP) and lateral flow biosensors.

Mycobacterium kansasii is an opportunistic pathogen that causes both intrapulmonary and extrapulmonary infections. The symptoms of the pulmonary diseases caused by M. kansasii closely resemble Mycobacterium tuberculosis. Rapid and accurate differentiation of M. kansasii from M. tuberculosis, as well as other mycobacteria, is crucial for developing effective therapeutics and disease treatment. In this study, we combined loop-mediated isothermal amplification (LAMP) with lateral flow biosensors (LFB) to detect M. kansasii, by targeting the species-specific sequence of rpoB, a gene which encodes the ß subunit of bacterial RNA polymerase. The assay was validated to ensure that it was highly selective by testing M. kansasii, M. tuberculosis, other species of respiratory bacteria, and other nontuberculous mycobacteria. The detection limit of the assay was 1 fg/µL of DNA and 50 CFU of bacilli in sputum. The M. kansasii-LAMP-LFB assay is a fast, cheap, and accurate method for detecting M. kansasii by constant temperature amplification and simple interpretation.

Spatio-temporal analysis of socio-economic characteristics for pulmonary tuberculosis in Sichuan province of China, 2006-2015.

BACKGROUND: The disease burden caused by pulmonary tuberculosis (TB) in Sichuan province still persisted at a high level, and large spatial variances were presented across regional distribution disparities. The socio-economic factors were suspected to affect the population of TB notification, we aimed to describe TB case notification rate (CNR) and identify which factors influence TB epidemic are necessary for the prevention and control of the disease in Sichuan province. METHODS: A retrospective cross-sectional study and an ecological spatial analysis was conducted to quantify the presence and location of spatial clusters of TB by the Moran's I index and examined these patterns with socio-economic risk factors by hierarchical Bayesian spatio-temporal model. RESULTS: A total of 630,009 pulmonary TB cases were notified from 2006 to 2015 in 181 counties of Sichuan province. The CNR decreased year by year since 2007, from 88.70 to 61.37 per 100,000 persons. The spatial heterogeneities of CNR were observed during the study periods. Global Moran's I index varied from 0.23 to 0.44 with all P-value < 0.001. The Bayesian spatio-temporal model with parametric spatio-temporal interactions was chosen as the best model according to the minimum of Deviance Information Criterion (DIC)(19,379.01), and in which the quadratic form of time was taken. The proportion of age group and education year were all associated with CNR after adjusting the spatial effect, temporal effect and spatio-temporal interactions. TB CNR increased by 10.2% [95% credible interval (CI): 6.7-13.7%] for every 1-standard-deviation increase in proportion of age group and decreased by 23% (95% CI: 13.7-32.7%) for every 1-standard-deviation increase in education year. CONCLUSIONS: There were spatial clusters of TB notification rate in Sichuan province from 2006 to 2015, and heavy TB burden was mainly attributed to aging and low socioeconomic status including poor education. Thus, it is more important to pay more attention to the elderly population and improve socioeconomic status including promoting education level in Sichuan province to reduce the TB burden.

Findings from a pilot project to assess the feasibility of active tuberculosis case finding among seniors in rural Sichuan Province, China, 2017.

BACKGROUND: China has a substantial tuberculosis (TB) disease burden and an aging population. Seniors have a higher risk of developing TB disease compared to younger age groups. Active case finding (ACF) could help identify seniors with TB disease. METHODS: From March to June 2017, we included ACF during annual physical check-ups for persons aged ≥ 65 years in Bayi, Sichuan Province. Seniors with clinical TB symptoms (i.e., cough lasting ≥ 2 weeks and/or hemoptysis) or one or more risk factors (e.g., previous TB disease, diabetes, and heavy alcohol consumption) were offered chest x-rays. We used acid-Fast Bacilli smear and solid culture laboratory testing for TB confirmation. We calculated the yield (i.e., cases identified among seniors screened) and cost per new each TB case detected. Focus group-interviews were conducted with health care workers and seniors to evaluate project acceptability. Participation rates and acceptability were used to assess feasibility. RESULTS: Of the 2,393 seniors residing in Bayi, 2,049 (85.6%) were enrolled in the pilot project. Of these seniors, 794 (38.7%) presented with at least one TB risk factor and 74 (3.6%) had symptoms consistent with active TB disease. Three seniors (0.2%)-each presenting with at least one risk factor-were diagnosed with active TB. The project yielded 146 TB cases per 100,000 seniors screened; the cost per case detected was $4,897. Most workers supported ACF if additional resources and staff could be provided. Seniors appreciated the convenience of this integrated health service approach. CONCLUSIONS: Although the yield was lower than expected, ACF appeared feasible in Bayi. Targeting seniors with at least one known TB risk factor could help detect previously unidentified TB cases. However, similar projects in communities with a higher TB prevalence are needed to further evaluate the yield and required resources prior to implementation on a larger scale. Findings from our pilot project should be combined with data from these future ACF projects to improve TB screening criteria.

[Study on epidemic trend and control policy of tuberculosis in Sichuan province].

OBJECTIVE: To evaluate efficacy of tuberculosis control policy and provide scientific evidence for drawing up tuberculosis control program. METHODS: Data of the epidemiological survey for tuberculosis in Sichuan in 2000 were analyzed and part of the results were compared with that before. RESULTS: The prevalence of active pulmonary tuberculosis, the bacteriological positive prevalence and smear positive prevalence of pulmonary tuberculosis in 2000 were 544/100 000, 250/100 000 and 144/100 000, respectively, decreased by 41.8%, 30.0% and 35.0% respectively in comparison with 1990, and the annual reduction rates were 5.3%, 3.5% and 4.2% respectively during the past 10 years. The mortality of tuberculosis and pulmonary tuberculosis was 24/100 000 and 22/100 000, respectively, decreased by 20.0% and 12.0% respectively in comparison with 1990. The prevalence of tuberculosis in minority area and mountainous area were higher than that in city, countryside and hills. 71% of infectious patients were newly detected, 33.3% of which were re-treatment cases. The economic status was found the key factor affecting the implementation of tuberculosis control. CONCLUSIONS: The modern tuberculosis control strategy, which mainly targeted infectious patients and advocated DOTS policy, is the guarantee of sustainable development of tuberculosis control, though the prevalence of pulmonary tuberculosis decreased slowly in Sichuan during the past 10 years.