Classic problem-based learning ( PBL ) was applied in a medical microbiology course.The results of questionnaire survey showed most of the students were satisfied with the whole learning program.They thought the case was appropriate,and the discussing could increase their understanding of the knowledge.Based on the problems faced during the application and the students' feedback,the duty of the tutors,summary of the learning topic,arrangement of the course,application of different teaching methods,and selection of the tutors were discussed in detail.

Objective: To explore the methods of establishing and maintaining community injecting drug user (IDU) cohort. Methods: From June 2014 to June 2017, a community survey was conducted on basis of local needle and syringe exchange site to recruit 200 HIV sero-negative IDU for a prospective cohort study in Longyang district of Baoshan city, Yunan province. Follow-up was carried out every six month to investigate high risk drug use behavior and sexual behavior, and blood samples were collected from them for the tests of HIV and HCV serum antibodies. The cohort would be opened every 12 months to replenish the cohort to 200 subjects. Results: The follow up was conducted for 3 years in 229 IDUs. Cohort follow-up rate was 93.0% (213/229) for 6 months, 92.1% (211/229) for 12 months, 91.7% (200/218) for 18 months, 87.2% (190/218) for 24 months, 86.0% (172/200) for 30 months and 86.0% (172/200) for 36 months. Conclusion The community IDU cohort has a high follow-up rate.