Epidemiology And Screening Strategies For Chlamydia Trachomatis And Neisseria Gonorrhoeae Infections

Chapter ⅠMulti-City Study on Infections of Chlamydia trachomatis and Neisseria gonorrhoeae among Men Who Have Sex with Men in ChinaBackground:Chlamydia trachomatis(CT)and Neisseria gonorrhoeae(NG)infections are a priority for prevention and control of sexually transmitted disease(STD)in China.Men who have sex with men(MSM)are considered as a high-risk population for CT and NG infections.However,data regarding the prevalence of CT and NG infections among MSM in China are limited and fragmented.Objective:The purpose of this study was to investigate the prevalence and molecular epidemiology of CT and NG at different exposure sites in MSM population from 14 cities of the seven geographic regions involving 9 provinces in China.Methods:Specimens were collected from anorectal,oropharyngeal,and urethral sites in MSM.CT and NG infection was determined by nucleic acid testing and genotyping was performed on CT-positive specimens.Results:The results showed that the overall prevalence of CT and NG infection was 14.6%(95%CI 13.2-16.0%)and 5.7%(95%CI 4.7-6.6%),respectively.The CT/NG prevalence was the highest in South China and the lowest in Northeast China,and the prevalence was significantly different among different regions.The CT infection was most common at the anorectal site(11.4%,95%CI 10.1-12.6%),followed by urethral(3.4%,95%CI 2.7-4.1%)and oropharyngeal sites(1.7%,95%CI 1.2-2.2%).The NG infection was most common at the anorectal site(3.3%,95%CI 2.6-4.0%),followed by oropharyngeal(3.1%,95%CI 2.4-3.7%)and urethral sites(0.8%,95%CI 0.4-1.1%).The CT/NG infection was significantly associated with the age(younger than 30 years),number of homosexual partners(more than 3),and intercourse mode(mainly anal sex).Genotypes D(41.1%)and G(35.7%)were the most predominant CT strains in this population but there was no statistical difference in the distribution of CT strains across different regions(P=0.556).Genotypes D(69.2%)were the most predominant CT strains in pharynx,Genotypes D(39.0%)and G(39.0%)in rectum,Genotypes D(35.0%)and G(30.0%)in urethra but there was no statistical difference in the distribution of CT strains across different sites(P=0.205).No genotypes associated with lymphogranuloma venereum were found among CT-positive specimens.Conclusion:The high prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae in the MSM population,especially in the anorectal site,suggests that CT and NG screening of urogenital and extragenital sites should be strengthened,and comprehensive intervention programs should be developed for this population.Chapter ⅡStudy on Acceptability and Feasibility to Introduce Self-Sampling and Mailing for Tests of Chlamydia trachomatis and Neisseria gonorrhoeaeBackground:Expanding screening service for key population is an important measure to effectively control Chlamydia trachomatis(CT)and Neisseria gonorrhoeae(NG)infections.However,screening services provided by medical institutions still have limitations such as low coverage and weak convenience,so it is urgent to explore innovative CT and NG screening modes with the help of e-health.Objective:The purpose of this study was to explore the feasibility of online home-based self-sampling service among key population(MSM and young students).Methods:We developed the online home-based self-sampling service platform.MSM were recruited online or offline from the MSM communities and young students were recruited online from the youth health centers and student organizations.After completing a willingness survey on online home-based self-sampling service,those in need were provided with a self-sampling kit and testing service for CT and NG.Results:A total of 778 MSMs completed the willingness survey.90.4%of the respondents indicated that they were willing to self-collect urine,oropharyngeal swabs or anorectal swabs at home for testing of STDs.The respondents who self-reported having had sex with temporary partners were three times more likely to choose online home-based self-sampling service than those who had not(OR 3.24,95%CI 1.51-6.95).659 participants(84.7%)requested the online home-based self-sampling service,626(95.0%)returned samples to the designated laboratory,the detection rate among participants was 80.5%.A total of 520 young students(309 boys and 211 girls)participated in the questionnaire survey.21.7%of the respondents indicated that they were willing to take the online home-based self-sampling service.Respondents who self-reported having had sex were three times more likely to use online home-based self-sampling service than those who had not(AOR 2.96,95%CI 1.92-4.58).139 participants(26.7%)requested the online home-based self-sampling service,and 60(43.2%)returned samples to designated laboratory,the detection rate among participants was 11.5%.Conclusion:The acceptance of online home-based self-sampling service in MSM population is significantly higher than that of young students,and there is a higher acceptance of this service among people with risky sexual behaviors.This service is expected to be one of the important screening modes for expanding CT and NG screening services in key populations.Chapter ⅢPerformance of Using Pooled Urogenital,Anorectal and Oropharyngeal Specimens to Detect Chlamydia trachomatis and Neisseria gonorrhoeaeBackground:Given the diversity of sexual practices among men who have sex with men(MSM),it is particularly important to enhance extragenital screening for CT and NG.However,screening for multiple sites(rectum,orpharynx and urethra,)would significantly increase the cost and time of testing.Objective:Based on one of the most widely available nucleic acid testing platform,we evaluated the accuracy of pooled specimens from anorectal,oropharyngeal,and urethral sites in MSM population for detection of CT/NG infections.Methods:Among the MSM population,the sensitivity and specificity of the pooling approaches were calculated by comparing the results(positivity or negativity)detected using the triple-site pooled specimens(ex-ante and ex-post)with the single-site specimens(reference standards).Results:Among the 437 participants,anorectal site had significantly higher prevalence of CT(12.8%)than urogenital site(3.4%)or oropharyngeal site(2.7%).Anorectal(5.3%)and oropharyngeal sites(4.8%)had the higher prevalence rates of NG than urogenital site(1.1%).Using the results of the single-site specimens as the reference standards,sensitivity and specificity to detect CT were 0.99(95%CI 0.93-1.00)and 1.00(95%CI 0.98-1.00)in ex-ante pooling strategy and sensitivity and specificity to detect NG were 0.90(95%CI 0.76-0.97)and 0.99(95%CI 0.97-1.00).Using the results of the single-site specimens as the reference standards,sensitivity and specificity to detect CT were 0.99(95%CI 0.93-1.00)and 1.00(95%CI 0.99-1.00)in ex-post pooling strategy and sensitivity and specificity to detect NG were 1.00(95%CI 0.91-1.00)and 1.00(95%CI 0.99-1.00).Conclusion:The ex-ante and ex-post pooling approaches of anorectal,oropharyngeal,and urethral specimens showed high sensitivity and specificity for the detection of CT and NG infections,and could be used as a cost-saving screening strategy for MSM population.Chapter ⅣMeta-Analysis on Diagnostic Accuracy of Pooling Multiple Specimens for the Detection of Chlamydia trachomatis and Neisseria gonorrhoeaeBackground:Genital Chlamydia trachomatis(CT)infection is one of the most common reproductive tract infections,and routine screening for CT infection in sexually active populations has been promoted in some countries.However,a single test for each individual requires significant medical resources.Objective:Systematic literature review and meta-analysis were conducted on the accuracy of pooled specimens from different individuals for detection of CT/NG infections,so as to provide evidence for diagnostic characteristics of pooling of individual specimens.Methods:Published studies on the accuracy of pooled specimens from different individuals for detection of CT/NG infections were searched through Pubmed,Embase,CNKI,Wanfang and VIP databases.A bivariate mixed-effects model was used for overall value merging in sensitivity and specificity.Results:There were 18 articles evaluating the pooled specimens from different individuals for detection of CT/NG infections among general populations.Compared with the individual specimens,the pooled specimens of multiple individuals had an overall sensitivity of 0.98(95%CI 0.97-0.99)and specificity of 1.00(95%CI 1.00-1.00)for the detection of CT.Only two articles evaluated the pooled specimens from different individuals for detection of NG infections,with sensitivity ranging from 0.97 to 1.00 and specificity ranging from 0.99 to 1.00.Conclusion:The evaluation of pooled specimens from different individuals for detection of CT infections has been widely carried out in the general population and has shown high sensitivity and specificity,so it can be considered as a screening strategy for CT infection.Relatively few assessments have been made for NG infection.