Background The Human Papillomavirus (HPV) and Chlamydia trachomatis are the most prevalent Sexually Transmitted Infections (STIs) worldwide, and are associated cervical cancer and pelvic inflammatory disease, respectively. However, 80% of women testing positive are asymptomatic. In the Amazon region, young women, in particular, are widely exposed to the infections and their consequences. Objectives Determine the prevalence of sexual infection by HPV and C. trachomatis in young, sexually-active women treated at a university health program in a large city of the Brazilian Amazon region. Methods We amplified the L1 gene of HPV. We amplified ompA gene of C. trachomatis by nested PCR, and the study participants filled in a questionnaire on their social, epidemiological, and reproductive health characteristics. The data were analyzed using the Odds Ratio, to evaluate the degree of association of these variables with the observed infections. Results The prevalence of infection by HPV was 15.5% (47/303). This infection was recorded in 32.2% of the women of less than 25 years of age (OR:3.02 [CI95%] = 1.32–6.92; p = 0.014), 17.9% of the single women (OR: 2.41 [CI95%] = 1.22–4.75; p = 0.014), 23.8% of the women that reported having first sexual intercourse at less than 15 years of age (OR: 2.22 [CI95%] = 1.16–4.23; p = 0.021), 20% of those that reported having had more than one sexual partner during their lifetime (OR: 3.83 [CI95%] = 1.56–9.37; p = 0.003), and in 28.3% that use oral contraceptives (CI95% = 1.33–5.43; p = 0.008). The prevalence of sexual infection by C. trachomatis was 4.6% (14/303), and this bacterium was present in 16.1% of the young women of less than 25 years of age (OR: 2.86 [CI95%] = 1.33–5.43; p = 0.008). Conclusions We found a high prevalence of HPV in young, unmarried women who started their sex lives early, who had several sexual partners in their lives and who used oral contraceptives. The prevalence of C. trachomatis was high only in young women. Our data are in accordance with other studies in Brazil and in the world and may serve to base the formulation of diagnostic and screening measures for these infections in women in the Amazon.

Chlamydia trachomatis uroinfection has become, in recent years, the most prevalent sexually transmitted infection worldwide, affecting quality of life and causing severe morbidity and mortality. This infection is silent and can lead to long-term reproductive complications. This study evaluates the prevalence and distribution of C. trachomatis genotypes in sexual infections of women from Belém, Amazon, Brazil. A cross-sectional, descriptive and prospective study was carried out from March 2019 to February 2020. Endocervical secretions were collected and DNA was extracted from these samples for ompA gene amplification by nested PCR and agarose gel electrophoresis. Positive samples were genotyped by nucleotide sequencing. The strains were genotyped by comparing the sequences of this study with those deposited in a public database. The Odds Ratio test was used to assess the relationship between infection and the variables investigated. A total of 230 samples were included in the analyses, of which 11 were positive for infection with a mean age of 44.18 years. We found no significant association between infection rates and the different variables investigated. One of the sequenced samples was diagnosed as genotype D, while all other samples were genotype F. The low prevalence of C. trachomatis in the sexual infections recorded in the present study, and the prevalence of genotype F, may be related to the relatively advanced age of the participants. Our results reinforce the importance of preventing late sequelae in the female population of the Amazon.