Community-based active case finding for tuberculosis in rural western China: a cross-sectional study.

SETTING: Current passive case finding strategies are not effective at identifying tuberculosis (TB) patients in rural China. OBJECTIVE: To evaluate a community-based, active case finding (ACF) scheme in identifying symptomatic individuals with TB. DESIGN: We conducted door-to-door household visits of all residents aged 15 years at two rural sites to screen for TB symptoms. Individuals with symptoms were enrolled and asked to provide three sputum samples. All participants underwent chest X-ray, and microbiologic detection of Mycobacterium tuberculosis from sputum samples using microscopy, solid culture and Xpert® MTB/RIF was performed. RESULTS: Among the 19 334 residents screened for TB symptoms, 865 (4.5%) reported having 1 symptom. A total of 52 TB cases were detected, 11 of whom had microbiologic confirmation. Xpert identified all five M. tuberculosis culture-positive cases and yielded an additional three diagnoses. Prevalence of newly detected TB at the two sites through ACF was respectively 475 and 196 per 100 000 population. These estimates are respectively four and eight times, on average, higher than those identified through passive surveillance during the previous 5-year period for the two sites. CONCLUSION: Community-based symptom screening followed by laboratory tests was found to be feasible and effective in increasing TB case finding in rural China.

Cloning and expression of class I chitinases in Hami melon after Penicillium infection.

Chitinases are important disease-related proteins that play critical roles in plant defense against disease. To investigate the function of chitinases in the resistance of Hami melon to Penicillium infection, the gene encoding chitinases, HmCHT-2, was cloned and RT-PCR was used to measure expression levels of HmCHT-2. When the Hami melon was infected by Penicillium sp after 0, 12, 36, 48, 60, and 72 h. The results showed that comparing to the control group, the time of expression levels reaching to the peak delayed and the expression levels maintained at a significantly high level for a longer time. These results suggest that HmCHT-2 may contribute to the defense of Hami melon against fungal infection.

Cloning of superoxide dismutase from post-harvest Hami melon and quantitative expression analysis before and after disease.

Primers were designed according to the Cu/Zn-SOD gene sequences of cloned Cucurbits plants (cucumbers and watermelons) available in NCBI. Total RNA from Hami melon pulp was used as a template. Following RT-PCR amplification, a 403-bp fragment of the Hami melon Cu/Zn-SOD gene was obtained. According to alignment in BLAST and phylogenetic tree analysis, the cloned gene fragment was confirmed to be the Hami melon Cu/Zn-SOD gene sequence. Real-time fluorescence quantitative expression analysis indicated that there were differences in the expression of SOD mRNA expression before and after infection by blue mold. mRNA expression was maximal 24-h after infection, indicating that the product of the SOD gene plays an important role in the rotting and degeneration of Hami melons as a consequence of bacterial infection during the preservation period.

Effect of antagonistic yeast XL-1 on resistance-associated enzyme activities in postharvest cantaloupe.

The effect of the antagonistic yeast XL-1 on resistance-associated enzyme activities in postharvest cantaloupe was studied by inoculating the antagonistic yeast XL-1. Cantaloupes were sterilized, dried in air, and soaked in antagonistic yeast treatment liquid for 30 s. After drying in air, the cantaloupe was stored at room temperature (2°-5°C). The activities of resistance-associated enzymes in cantaloupe like polyphenol oxidase, ß-1,3-glucanase, peroxidase, and superoxide dismutase were measured every 7 days. Our results indicated that the antagonistic yeast XL-1 significantly improved the activity of ß-1,3-glucanase and chitinase to promote the disease resistance of postharvest cantaloupe.