Sexually Transmitted Infections in Adolescents: Age-specific Issues

Adolescence is the time when the most significant physical, psychological and social changes occur, as well as the beginning of sexual experiences. The World Health Organization defines the adolescent age range as 10–19 years old.1 Sexually transmitted infections (STIs) are a global concern and relevant for adolescents’ health. Adolescent and young people present the highest rates and are disproportionately represented.2,3 Physicians attending this age group are easily faced with STIs and should be aware of STIs age-related issues. Different factors are linked to a higher risk of STIs in adolescence.4 Age-specific behavioral factors include multiple, new and concurrent partners, inconsistent and declining condom use, early sexual initiation and alcohol or drug use (this factor may be associated with multiple partners, condomless sex, or sex with a high-risk partner). Risk-taking and experimentation are usually added to the increased autonomy and self-identity that develop during adolescence. Cervical ectopy and cervical-vaginal microbiome in young women are the main biological susceptibility factors. Difficulties in accessing health services are also relevant related factors. STIs in adolescents should be approached in a comprehensive way, including global aspects of their sexuality, as consent, reproductive health, gender identity or body image, through open and free from judgment discussions. EPIDEMIOLOGY The impact of STIs is the greatest in young people: adolescents (15–19 years old) present the second highest rate, just after young adults (20–24 years old).2,3 STIs are often asymptomatic, so screening programs, which present a great variability among countries/regions and periods, influence the differences in the reports. In addition, barriers to the access and/or disruptions in STI-related prevention and care activities have a pronounced impact on trends in STI surveillance data. In 2022, the number of reported cases increased in Europe compared with the previous year, with gonococcal cases rising by 48%, syphilis cases by 34% and chlamydial cases by 16%.2 Chlamydial infections are the most prevalent bacterial STIs worldwide, especially among adolescent girls (second highest in women 15–19 years, nearly 600/100,000).2 Gonococcal infections come second, with a distributed incidence among gender in adolescents (27/100,000 in 15–19 years).2 In the United States, although rates have increased since 2020, the national rate of reported chlamydia in 2023 is still lower than the rate in 2019, suggesting that reductions in chlamydia screening coverage may have persisted (highest in women 15–19 years, 2566.1 per 100,000)3 Some screening programs have been reinforced, targeting especially adolescents and young adults. Thus, in France, since September 2024, young people under 26 years old can be screened for human immunodeficiency virus (HIV), hepatitis B virus (HBV), syphilis, chlamydial and gonococcal infections in medical laboratories, without the need for a medical request.5 CLINICAL PRESENTATION STIs in adolescents show great clinical variability as pathogens may manifest diverse, well-defined clinical syndromes (eg, genital ulcers, urethritis and cervicitis) or mild, non-specific symptoms (eg, dysuria, pruritus) that disappear shortly after onset. Furthermore, the approach to these infections becomes arduous given the high frequency of coinfections that can cause local or systemic symptoms that resemble the same clinical picture, such as human papillomavirus (HPV) or Molluscum contagiosum and syphilis or HIV, respectively. However, the most relevant fact in this age group is that up to 50%–60% of STIs are asymptomatic.6 This is especially frequent in adolescent women as lesions are often imperceptible due to their biological conditioning factors, causing latent infections to persist and increase the risk of sequelae. Late diagnosis of STIs in adolescents can lead to serious complications in the short, medium and long term: pelvic inflammatory disease, epididymitis, infertility, vertical transmission and urogenital cancer, among others. DIAGNOSIS As in the general population, Nucleic Acid Amplification Tests are the most sensitive tests and are the recommended test for detecting Chlamydia trachomatis or Neisseria gonorrhoeae infections. It is recommended to perform, in addition, a culture in cases of cervicitis or urethritis if N. gonorrhoeae is suspected, for assessing antimicrobial susceptibility.7 Two main elements hinder the approach to STIs in adolescents. First, the fear of revealing relevant information about their sexuality, which can be considered a risk of breaching their confidentiality. Thus, guiding the STI test to perform (as extragenital swabs) only by sexual history can be challenging in adolescents. Second, the barriers to access to the healthcare system, discussed later. All interventions aimed at developing a complete and adequate clinical assessment (thoroughness psychosocial consideration interviews, proper privacy measures, point-of-care STI tests and on-site treatment promotion) have a significant impact on the control of STIs in adolescents.8 Two approaches can be relevant for STI diagnosis of age-related issues. Primarily, self-sampling facilitates the acceptance of STI screening in adolescents.6,9 Next, point-of-care STI tests would help decentralize STI care, thus achieving greater coverage. Moreover, these tests would not only facilitate a short-term diagnosis but would also improve targeted antibiotic treatment at the same visit.10 There is a high prevalence of C. trachomatis and N. gonorrhoeae in patients treated for STIs in the preceding months (reinfection rather than treatment failure). Thus, these individuals should be retested 3 months after treatment completion or whenever the following medical care visit occurs within the following 3–12 months.6 If a STI is suspected or screened, a global STI screening should be considered and specific tests (swabs/urine and serologies) should be conducted, as well as tests for unplanned pregnancy. TREATMENT Adequate and early treatment of STIs is essential for both individual and public health concerns. Nonetheless, low symptomatic expression and healthcare workers’ lack of suspicion can connote that the treatment is deferred to a second medical consultation once results are available. Adolescents, due to barriers to accessing health care and age-related particularities, may more easily miss this follow-up appointment, resulting in a higher number of untreated diagnosed STIs. Presumptive syndrome-based treatment is thus usually proposed when follow-up cannot be ensured,6 which is common in adolescents (Table 1). TABLE 1. - Syndrome-Based Presumptive Treatments and Treatment Regimens for Specific Infections in Adolescents Treatment Comments Syndrome Urethritis/cervicitis/proctitis Ceftriaxone 500 mg IM in a single dose plus azithromycin 1 g orally in a single dose (preferred for treatment adherence)orCeftriaxone 500 mg IM in a single dose plus doxycycline 100 mg orally 2 times/d for 7 d (more effective for chlamydial rectal infection) In case of proctitis, extend doxycycline to 21 d if LGV is confirmed or suspected First clinical episode of genital herpes Acyclovir 400 mg orally 3 times/d for 5–10 dorValacyclovir 1 g orally 2 times/d for 5–10 d Treatment should be started within the first 5 d, or as long as new lesions appear or systemic symptoms persist Episodic therapy for recurrent genital herpes Acyclovir 800 mg orally 2 times/d for 5 dorAcyclovir 800 mg orally 3 times/d for 2 dorValacyclovir 500 mg orally 2 times/d for 3 dorValacyclovir 1 g orally once daily for 5 d Episodic treatment of recurrent herpes is most effective if therapy is initiated within 1 d of lesion onset or during the prodrome Microorganism Neisseria gonorrhoeae Ceftriaxone 500 mg IM in a single dose Perform a test-of-cure 14 d after treatment in case of pharyngeal infection Chlamydia trachomatis Azithromycin 1 g orally in a single dose (preferred for treatment adherence)orDoxycycline 100 mg orally 2 times/d for 7 d (preferred for rectal infections) Perform a test-of-cure after treatment if doxycycline is not used Primary, secondary and early latent syphilis Benzathine penicillin G 2.4 million units IM in a single dose Late latent and tertiary syphilis with normal CSF examination Benzathine penicillin G 7.2 million units total, administered as 3 doses of 2.4 million units IM each at 1-wk intervals Neurosyphilis, ocular syphilis and otosyphilis Aqueous crystalline penicillin G 18–24 million units per day, administered as 3–4 million units IV every 4 h for 10–14 d CSF indicates cerebrospinal fluid; IM, intramuscular; IV, intravenous; LGV, lymphogranuloma venereum. Even if age and weight do not usually reduce the treatment choice in adolescence, there can be some limitations due to delayed drug approval in this group compared with adults. Adherence to treatment can be challenging in adolescents. Even if a 7-d doxycycline regimen has shown a higher cure rate for C. trachomatis infections, especially rectal, when nonadherence is a substantial concern, azithromycin 1 g one-dose regimen is an alternative treatment option, but might require posttreatment evaluation and testing.6,11 PREVENTION STI prevention strategies should be tailored to age, sex and specific circumstances, considering related vulnerabilities.8 General prevention recommendations for adolescents are: - Provide comprehensive sexual education from childhood, through healthcare centers, community settings and other relevant environments, using clear, understandable language and ensuring confidentiality. Information can be shared using various media platforms, such as online, mobile phone technology and participatory approaches.12 The information should be scientifically accurate, age-appropriate and cover sexual and reproductive health issues, promoting a positive approach to sexuality.13 It should teach prevention methods, recognize signs and symptoms of STIs and emphasize the importance of seeking treatment. Creating an open environment for discussion, free from stigma and discrimination, is essential (Table, Supplemental Digital Content 1, https://links.lww.com/INF/G243). Additionally, sexual health training for healthcare professionals is crucial to enhance their knowledge and skills while reducing stigmatizing attitudes.8 - Promote efficient and affordable access to prevention products, including barrier methods (internal/external condoms) and lubricants, through healthcare centers, schools and community organizations.8 - Vaccinate to prevent 3 viral STIs: HBV, hepatitis A virus and HPV.8 Mpox vaccine should be considered in people over 12 years old.,7,14 Although unapproved for this indication, the 4-component serogroup B meningococcal vaccine may significantly reduce gonorrhea incidence, especially in adolescents.15 - Perform periodic STI screening in sexually active adolescents. This early detection and treatment strategy is vital for infections that are often presented asymptomatically. The recommended frequency for STI screening is annual for C. trachomatis and N. gonorrhoeae in all young women and young men who have sex with men, with a higher frequency depending on their risk of exposure.6,7 - Trace contacts following an STI diagnosis. This is crucial for notifying and testing sexual partners, enabling the management of asymptomatic cases.8 - Offer pre-exposure prophylaxis for HIV. Although relatively new, it has proven to be effective and safe for adolescents when offered as part of a comprehensive HIV prevention and sexual and reproductive health service package.16 - Facilitate access to postexposure prophylaxis (PEP) using antiretroviral drugs for individuals with potential recent exposure to HIV.8 PEP education should be part of comprehensive adolescent care, ensuring that adolescents understand its availability and the importance of seeking immediate medical attention after potential HIV exposure. Besides, several studies have demonstrated that PEP with doxycycline, administered within 72 hours of high-risk sexual exposure, reduces the incidence of syphilis, chlamydia and gonorrhea in targeted populations.17 SEXUAL AND GENDER MINORITIES Compared with heterosexual and cisgender youth, sexual and gender minority youth (as defined elsewhere)18 report a lower rate of condom use in their last sexual intercourse, earlier sexual debut (before age 13) and a larger number of sexual partners in their lifetime, in relationship with different factors described elsewhere,19 which can lead to increased rates of STIs.20,21 Moreover, compared with cisgender youth, sexual and gender minority adolescents experience worse access to health services due to a noninclusive health environment.21 Pediatricians should be familiar with the concepts of sexual and gender minorities and be aware that sexual identity is a property of individuals that develops throughout childhood and adolescence.22 SEXUAL ABUSE Healthcare providers attending adolescents should be aware of the possibility of sexual violence and screen for sexual abuse or assault while taking a sexual history. Many adolescents will not spontaneously disclose that they have been forced or pressured to have sex.23 Young women are at increased risk of experiencing sexual violence from partners, ex-partners or third parties in the past 12 months. In Spain, global prevalence surveys show that the prevalence of such violence among the youngest women (16–24 years old) is 5.9% and among women aged 25 and over is 1.3%.24 Female adolescents between the ages of 12 and 17 account for 1 in 5 sexual assault reports, and those aged 16–19 are 4 times more likely than any other group to be victims of sexual assault.25 In addition, data from the United States show that between 40% and 60% of all rape victims are under the age of 18—most of them adolescents—and there are estimations that two-thirds of minors who have experienced sexual abuse were 12–17 years old when it first occurred.26 HEALTHCARE SERVICE ACCESS In addition to common barriers to care affecting people of all ages, adolescents face unique obstacles such as the need (or belief in the need) for parental consent and notification, confidentiality issues, lack of information about accessing health care services and the scarcity of providers trained to meet their needs.27,28 Adolescents’ access to the health system may also vary by country and area (financial issues, number of resources in urban vs. rural areas). On the other hand, health professionals caring for adolescents are not always aware of the age of majority for health care decisions and the mature minor doctrine, which allows the judgment of the treating clinician regarding an individual minor (usually from the age of 12) to demonstrate they are mature enough to make a medical decision on their own behalf. The mature minor doctrine is applied unevenly in North America and Europe, so each practitioner must be aware of the legal context in his or her country to guarantee the rights of adolescents.29,30 In any case, adolescents, irrespective of age, should be permitted access to counseling and advice without the consent of their parents or guardians. Making services accessible include ensuring that they are affordable, confidential and safe to access and are provided at times that are convenient. Adolescents should be made aware of their rights to confidentiality, and any limits of confidentiality made clear by those with mandatory reporting responsibilities.11 CONCLUSIONS STIs are relevant for adolescents’ health. Age-related issues should be considered by every healthcare worker attending adolescents for better prevention, screening, diagnosis and treatment of STIs.