Hiransuthikul A, Janamnuaysook R, Sungsing T, et al

High burden of chlamydia and gonorrhoea in pharyngeal, rectal and urethral sites among Thai transgender women: implications for anatomical site selection for the screening of STI

Sexually Transmitted Infections Published Online First: 13 April 2019. doi: 10.1136/sextrans-2018-053835

Abstract

Objective Comprehensive data on Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections to guide screening services among transgender women (TGW) are limited. We studied the burden of CT/NG infections in pharyngeal, rectal and urethral sites of Thai TGW and determined missed CT/NG diagnoses if selected site screening was performed.

Methods Thai TGW were enrolled to the community-led test and treat cohort. CT/NG screening was performed from pharyngeal swab, rectal swab and urine using nucleic acid amplification test. CT/NG prevalence in each anatomical site was analysed, along with the relationships of CT/NG among the three anatomical sites.

Results Of 764 TGW included in the analysis, 232 (30.4%) had CT/NG infections at any anatomical site, with an overall incidence of 23.7 per 100 person-years. The most common CT/NG infections by anatomical site were rectal CT (19.5%), rectal NG (9.6%) and pharyngeal NG (8.1%). Among 232 TGW with CT/NG infections at any anatomical site, 22%–94.4% of infections would have been missed if single anatomical site testing was conducted, depending on the selected site. Among 668 TGW who tested negative at pharyngeal site, 20.4% had either rectal or urethral infections. Among 583 TGW who tested negative at the rectal site, 8.7% had either pharyngeal or urethral infections. Among 751 TGW who tested negative at the urethral site, 19.2% had either pharyngeal or rectal infections.

Conclusion Almost one-third of Thai TGW had CT/NG infections. All-site screening is highly recommended to identify these infections, but if not feasible rectal screening provides the highest yield of CT/NG diagnoses. Affordable molecular technologies and/or CT/NG screening in pooled samples from different anatomical sites are urgently needed.

To the best of our knowledge, our analysis is the first to show the distribution of CT/NG infections by anatomical site among TGW. We found that approximately more than half of infections occurred exclusively at one anatomical site, especially rectal infections where 69% were isolated to the rectal site. Although our results indicate rectal screening has the highest yield of any CT/NG infection, if only single anatomical site screening were available rectal screening would still have missed 22% of the total infections identified. The results also demonstrated that the urethral site should not be used for single anatomical site screening since 94% of the total infections would have been missed. These results point to a critical need for TGW screening for CT/NG infections at all three anatomical sites.

Another important finding was that missed CT/NG diagnoses were more likely to occur in HIV-positive TGW than HIV-negative TGW. This may be because a higher proportion of sexual risk behaviours was reported among HIV-positive TGW compared with HIV-negative TGW. This again emphasises the importance of CT/NG screening at three anatomical sites. However, if resources limit the number of sites screened, clients with multiple partners or refusing to report the number of partners should prompt healthcare providers to test rectal and pharyngeal sites.

Our study indicates that Thai TGW have a high prevalence of CT/NG infections, with nearly one-third of participants having CT/NG infections at baseline. Our results suggest that a high proportion of CT/NG infections would be missed in sexually active TGW if single anatomical site screening was performed. Therefore, we strongly recommend CT/NG screening at all three anatomical sites among sexually active TGW. If all-site screening is not feasible, the rectal site should be screened to get the highest yield of CT/NG diagnoses, while rectal and pharyngeal screening should be prioritised for TGW who report multiple sexual partners. Affordable molecular technologies and/or CT/NG detection in pooled samples from different anatomical sites are urgently needed for routine asymptomatic CT/NG screening among TGW in resource-limited settings.