BACKGROUND: Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) are among the sexually transmitted infections (STIs) with high rates worldwide. These infections disproportionately affect AMSM and ATGW. This population's prevalence rates by anatomical site, sociodemographic and behavioral data (SBD) are scarce in Brazil and elsewhere.
METHODS: PrEP1519 is a prospective, multicenter, open-label PrEP demonstration cohort study of AMSM and ATGW aged 15-19. For this analysis, we included 246 adolescents who enrolled in PrEP1519 between April 2019-February 2021 in the city of Salvador, Northeast Brazil. They were tested for NG and CT by qPCR using swabs collected from oral, anal, and urethral anatomical sites. We assessed the association between SBD and the prevalence of STIs by Pearson's chi-squared test or Fisher's exact test. Poisson regression with robust variance was used to estimate the adjusted prevalence ratio (PR) and 95% confidence interval (95%CI).
RESULTS: The prevalence of STIs by anatomical site is summarized below:

Table. Prevalence of N. gonorrhoeae and C. trachomatis. PREP1519, Northeast Brazil, 2019-2021

STI	Any site		Oral (n=245)		Anal (n=210)		Urethral (n=213)
	n (%)	95%CI	n (%)	95%CI	n (%)	95%CI	n (%)	95%CI
N. gonorrhoeae	37 (17.9)	13.21-23.74	23 (9.4)	6.31-13.76	16 (7.6)	4.71-12.11	4 (1.9)	0.70-4.92
C. trachomatis	12 (5.9)	3.36-10.10	3 (1.2)	0.39-3.75	5 (2.4)	0.99-5.62	4 (1.9)	0.70-4.92
Coinfection	1 (0.5)	0.06-3.47	-	-	1 (0.5)	0.06-3.47	-	-

Factors associated with NG was a lower level of schooling (PR=2.08; 95%CI 1.07-4.04) and engaging in receptive anal sex in the last three months (PR=2.45; 95%CI 0.91-6.65). Condomless oral sex in the previous three months was associated with CT (PR=3.75; 95%CI 1.28-11.00) and lower level of schooling (PR=3.00; 95%CI 0.90-9.98), but the 95%CI was wide and imprecise.
CONCLUSIONS: We found a high prevalence of NG and CT acquisition among AMSM and ATGW, especially in extragenital sites. These findings highlight the need for testing in multiple anatomical sites among HIV-vulnerable populations. The association between education, receptive anal sex and condomless oral sex with STIs expresses the role social and behavioral factors play in the greater vulnerability of AMSM and ATGW to these infections. Therefore, inclusive and comprehensive sexual health and behavior counseling taylored for these populations, especially those who are more willing to engage in riskier sexual practices, could further improve HIV and STI prevention and care.

Download the e-Poster (PDF)