Sexually transmitted infections among at-risk women in Ecuador: implications for global prevalence and testing practices for STIs detected only at the anorectum in female sex workers.

OBJECTIVES: Anorectal sexually transmitted infections (STIs) such as Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG), present treatment challenges, potentially increase antibiotic resistance selection and if undetected may facilitate onward transmission. However, there are limited global prevalence data for anorectal STIs. We conducted a cross-sectional study to assess the prevalence and risk factors of non-viral genital and extragenital STIs in female sex workers (FSW) and female non-sex workers (NSW) in Ecuador. METHODS: 250 adult street and brothel FSWs and 250 NSWs, recruited from settlements in north-west Ecuador provided oropharyngeal and vulvo-vaginal swabs (VVS) as well as socio-demographic data. FSWs also provided anorectal swabs. PCR was used to detect CT, NG, Mycoplasma genitalium (MG) from all swabs and additionally Trichomonas vaginalis (TV) from VVS. Risk factors were analysed using logistic regression. RESULTS: Prevalence of FSW vaginal, anorectal and oropharyngeal infection was 32.0% (95% CI 26.5% to 38.0%), 19.7% (95% CI 15.1% to 25.2%) and 3.2% (95% CI 1.6% to 6.2%), respectively, with most vaginal infections being TV (23.4%; 95% CI 18.5% to 29.2%). Overall FSW STI prevalence, at any anatomical site was 39.7% (95% CI 33.8% to 46.1%), with 12.1% (95% CI 8.5% to 16.9%) of infections detected only at the anorectum. Of all the CT and/or NG infections, 64.4% (95% CI 50.4% to 78.4%) were detected only at the anorectum. STI prevalence in NSWs in the vagina and oropharynx were 5.6% (95% CI 3.4% to 9.2%) and 0.8% (95% CI 0.2% to 2.9%), respectively, with most vaginal infections being MG (3.2%; 95% CI 1.6% to 6.2%). In multivariable analysis, risk factors among brothel-based FSWs for having an anorectal STI were vaginal CT, NG or MG (p<0.001), vaginal TV (p=0.029) and being 'in a relationship' (p=0.038). CONCLUSIONS: High prevalence of CT and NG detected only at the anorectum in these FSWs indicate the possibility of missing significant infections if providing only genital testing and calls for greater research into the potential impact on global STI estimates if extragenital infections among at-risk women are not identified.

Single gene targeted nanopore sequencing enables simultaneous identification and antimicrobial resistance detection of sexually transmitted infections.

OBJECTIVES: To develop a simple DNA sequencing test for simultaneous identification and antimicrobial resistance (AMR) detection of multiple sexually transmitted infections (STIs). METHODS: Real-time PCR (qPCR) was initially performed to identify Neisseria gonorrhoeae (NG), Chlamydia trachomatis (CT), Mycoplasma genitalium (MG) and Trichomonas vaginalis (TV) infections among a total of 200 vulvo-vaginal swab samples from female sex workers in Ecuador. qPCR positive samples plus qPCR negative controls for these STIs were subjected to single gene targeted PCR MinION-nanopore sequencing using the smartphone operated MinIT. RESULTS: Among 200 vulvo-vaginal swab samples 43 were qPCR positive for at least one of the STIs. Single gene targeted nanopore sequencing generally yielded higher pathogen specific read counts in qPCR positive samples than qPCR negative controls. Of the 26 CT, NG or MG infections identified by qPCR, 25 were clearly distinguishable from qPCR negative controls by read count. Discrimination of TV qPCR positives from qPCR negative controls was poorer as many had low pathogen loads (qPCR cycle threshold >35) which produced few specific reads. Real-time AMR profiling revealed that 3/3 NG samples identified had gyrA mutations associated with fluoroquinolone resistance, 2/10 of TV had mutations related to metronidazole resistance, while none of the MG samples possessed 23S rRNA gene mutations contributing to macrolide resistance. CONCLUSIONS: Single gene targeted nanopore sequencing for diagnosing and simultaneously identifying key antimicrobial resistance markers for four common genital STIs shows promise. Further work to optimise accuracy, reduce costs and improve speed may allow sustainable approaches for managing STIs and emerging AMR in resource poor and laboratory limited settings.

Sexually transmitted infections and factors associated with risky sexual practices among female sex workers: A cross sectional study in a large Andean city.

BACKGROUND: There are limited published data on factors related to risky sexual practices (RSP) affecting sexually transmitted infections (STIs) among female sex workers (FSWs) in Ecuador. METHODS: Cross-sectional study of FSWs presenting for a consultation in a primary health care centre during 2017. A questionnaire was administered to collect information on RSP and potential risk factors including age, membership of an FSW association, self-report of previous STI diagnosis, previous treatment for suspected STI and temporary migration for sex work. Associations between RSP and potential risk factors were estimated by logistic regression. The proportion of STI was estimated from vaginal swabs by real-time PCR for four sexually transmitted pathogens (Neisseria gonorrhoeae, Trichomonas vaginalis, Chlamydia trachomatis, and Mycoplasma genitalium). RESULTS: Of 249 FSWs recruited, 22.5% had reported RSPs at least once during sex work. Among FSWs reporting unprotected vaginal sex in the previous three months, 25.5% had at least one other RSP type. 17.6% (95%CI 13.3-22.8) had at least one active STI. Prevalence of co-infections was 2.4% (95%CI 1.1-5.2). In multivariable analysis, RSP was associated with age (adjusted OR 1.06; 95%CI 1.02-1.10), membership of an FSWs association (aOR 3.51; 95%CI 1.60-7.72) and self-reported previous STI (aOR 3.43; 95%CI 1.28-9.17). CONCLUSIONS: Among a population of female sex workers with high proportion of STIs, increasing age and belonging to an FSWs association was associated with a higher likelihood of engaging in RSP with clients. Engaging with FSWs organisations may reduce the burden of STI among sex workers.