RESUMO
@#The Streptococcus mutans (S. mutans) phage, as one of the principal pathogenic bacteria of dental caries, is a main cause of the formation and development of dental caries due to its overproliferation in dental plaque biofilms. Bacterial viruses, also known as bacteriophages, have the capability of specifically infecting bacteria and effectively degrading bacterial biofilms. S. mutans phages, therefore, may prevent and control caries. Therapy based on phages has been applied in many fields, but the application of S. mutans phages in caries remains exploratory. This article will review the research progress of S. mutans phages in clinical caries prevention, aiming to provide a new idea for the clinical prevention of caries. The results of the literature review show that the living bacteriophage system has the advantages of high specificity, high affinity and good safety. However, due to its unstable structure, it can be processed into a more stable formulation by freeze-drying, spray drying, adding stability enhancers, or incorporating bacteriophages into ointments, biodegradable polymer matrices or particles to a certain extent to improve stability. The lysozyme produced by phages can digest the bacterial cell wall and release the assembled phage particles, which effectively cleave biofilms. In addition, the antigen binding fragment library for cariogenic pathogens was screened by phage display technology, and the purpose of caries prevention and treatment was achieved by passive immunization of antigen binding fragments. However, the host range of bacteriophages is narrow, so this kind of problem can be overcome by phage combined with traditional therapy or other drug use or cocktail therapy with multiple phages in clinical caries prevention and control.
RESUMO
Objective@#To investigate sexual behavior and related factors among middle school students in Chengdu,and to provide a reference for improving the content and the way of their sexual health education.@*Methods@#Stratified cluster sampling was used to select 935 students from 11 schools in Chengdu. A self-designed questionnaire was implemented to estimate sexual behavior and related factors.@*Results@#Thirty-six (3.9%) students reported sexual behavior during the past year. The difference between boys (5.6%) and girls (1.7%) was of statistical significance(χ2=9.79，P<0.01). 77.8% (28/36) of all the participants reported first sexual contact experience, 2.4% (22/935) reported homosexual behavior. Five out of 935 students had experienced unplanned pregnancy, four of them chose to have an abortion. Multivariate Logistic regression showed that masturbation experience, talking about sex-related things with friends, asking for help from friends when in sex-related troubles positively with higher risk of sextual behavior(OR=6.67,0.30,0.28,P<0.05).@*Conclusion@#There are multiple types of unsafe sexual behavior among middle school students in Chengdu. Strategies including positive behavior support, peer education, sustainable environment and youth-friend services are essential for health education in the future.