Chlamydia, caused by the bacterium C. trachomatis, is the most commonly reported STI in the USA in all age groups, with highest prevalence in patients less than 25 years of age . Two-thirds of new cases arise in patients ages 15–24 years and an estimated 1 in 20 adolescent females is infected with chlamydia at any time [3, 13].
Presentation is variable; most infected individuals are asymptomatic. In symptomatic women, vaginal discharge, irregular menstrual bleeding, dysuria, and abdominal pain may be present. In men, mucoid or watery penile discharge, dysuria, or testicular pain may occur.
The gold standard for CT testing is now nucleic acid amplification tests (NAAT). First-catch urine, cervical swab, or urethral swab specimens can be obtained for NAAT. CDC recommends female vaginal swab and male first-void urine for optimal specimen collection . Most FDA approved NAATs allow for testing for both C. trachomatis and N. gonorrhoeae with a single specimen.
Gonorrhea is the second most commonly reported STI, caused by N. gonorrhoeae. Like chlamydia, prevalence is highest in patients less than 25 years of age .
Presentation for infected individuals with gonorrhea is variable, as many are asymptomatic. In symptomatic women, vaginal discharge, irregular menstrual bleeding, dysuria, and abdominal pain are commonly present. In men, mucopurulent discharge, dysuria, or testicular pain can occur.
NAAT is preferred for diagnosis of N. gonorrhoeae. First-catch urine, cervical swab, or urethral swab specimens can be obtained for NAAT. CDC recommends female vaginal swab and male first-void urine as optimal specimen sources. NAATs may also be used for testing of extragenital sites (rectum, pharynx), although none have been FDA approved for this purpose at the present time. Culture remains the gold standard in cases when there is concern for antibiotic resistance or prior treatment failure. Treatment failures should be reported to the local health department, as there is growing concern for increasing antibiotic resistant N. gonorrhoeae [21, 22].
Quinolones are no longer recommended due to high resistance rates. Oral cephalosporins are no longer recommended due to emerging resistance patterns . Dual treatment with IM ceftriaxone and azithromycin or doxycycline is recommended to slow progression of antimicrobial resistance.
Syphilis is caused by the spirochete Treponema pallidum. This infection can present with four stages if left untreated: primary, secondary, latent, and tertiary. Presentation is highly variable and has been called “the great imposter,” as many of the signs and symptoms are nonspecific.
Incubation period is 9–90 days. Primary symptoms occur on average 21 days post-exposure. Primary syphilis involves a chancre, a painless ulcer at site of infection. Characteristics include a sharply demarcated border with a smooth, red base. Generally, there is a solitary lesion, although multiple lesions can occur. Regional lymphadenopathy may be found with primary syphilis. The chancre typically resolves in 3–6 weeks without treatment and can often go unnoticed and as a result, untreated.
Secondary syphilis typically occurs 4–10 weeks after onset of the chancre. Symptoms include a diffuse, nonpruritic rash that can occur anywhere on the body, including on the palms or soles. Appearance is highly variable and can include macular, papular, annular, or pustular lesions with hyperpigmentation or hypopigmentation.
Latent syphilis occurs after secondary syphilitic symptoms resolve. This stage can last up to 25 years before progressing to tertiary complications. Individuals are asymptomatic during this phase. Latent syphilis is divided into early latent or late latent phases based on proximity to primary/secondary symptoms or last documented negative testing. New seroconversion with documented negative testing or primary/secondary symptoms within the last year is considered early latent phase. A diagnosis of late latent syphilis is applied when primary/secondary symptoms occurred >1 year ago, for those whose last negative testing was obtained >1 year ago or if no prior history of negative testing is available.
Tertiary syphilis is a disseminated infection and can affect any organ system, most commonly with neurologic, ophthalmic, auditory, and cardiac involvement. Gummas—granulomatous lesions—can involve skin, soft tissue, viscera, and bones.
Making a diagnosis of syphilis requires both a nontreponemal test (rapid plasma reagin [RPR] or venereal disease research laboratory [VDRL]) and a treponemal test (fluorescent treponemal antibody absorbed [FTA-ABS], T. pallidum passive particle agglutination [TP-PA], enzyme immunoassay, chemiluminescence immunoassay). Darkfield microscopy in early syphilis is highly specific, but insensitive. Anyone with a positive nontreponemal test should receive a treponemal test in order to confirm a diagnosis of syphilis. There are a number of conditions that may lead to false positive nontreponemal results, including pregnancy, autoimmune conditions, immunizations, IV-drug use, and age .
Nontreponemal titers should be followed post-treatment. A fourfold decrease in titers (e.g., from 1:64 to 1:16) demonstrates an adequate response to treatment. Most patients will have lifelong reactivity on treponemal testing after a syphilis infection.
Benzathine penicillin is the drug of choice and treatment regimen is based on staging. Sex partners within the last 90 days should be tested and treated.
While HIV rates in the USA overall are in decline, youth ages 13–24 still account for nearly 10,000 new cases of HIV within the USA each year . The majority of these diagnoses occurred among MSM, particularly African American and Hispanic MSM. CDC recommends screening for all men and women ages 13–64 and routinely for individuals seeking evaluation and treatment for STIs. MSM should be screened at least annually if status is unknown or negative. Counseling that includes risk reduction, screening, and linkage to care for positive youth should remain a priority for providers .
Information regarding clinical course and management of HIV infection may be found in more detail elsewhere.
Herpes simplex virus
Herpes simplex viruses are common and result in lifelong viral infection. Two subtypes, type 1 (HSV-1) and type 2 (HSV-2), exist. Historically, HSV-1 has been associated with orofacial disease and HSV-2 with genital disease; however, infection with either serotype has been known to cause disease at both sites . Recurrence is more common in HSV-2.
It is believed that at least 50 million Americans are infected with HSV-2, with estimated prevalence rates of 1.4 % among 14–19-year-olds and 10.5 % among 20–29-year-olds . Most seropositive individuals—nearly 90 %—are either asymptomatic or do not recognize the symptoms, and thus go undiagnosed .
Incubation period is 2–12 days. Presentation can include single or multiple vesicles that rupture to form painful, shallow ulcers. Associated symptoms include perineal pain, vulvar edema, serosanguinous vaginal discharge, pruritis, dyspareunia, dysuria or urinary outflow obstruction, or proctitis. The primary episode is often the most severe and may be associated with tender lymphadenopathy and/or viremia with fever, malaise, or myalgias. Recurrences may be less severe and are often preceded by a prodrome that may include burning, tingling, tenderness, or pain prior to eruption of lesions. Without treatment, lesions typically last 8–10 days before spontaneous resolution.
Counseling should include education regarding potential for recurrence, triggers (e.g., stress, fatigue, illness, menses), recognizing prodrome, treatment options and education regarding transmission, asymptomatic shedding, and the importance of condom usage with all sexual activity.
Goal of treatment with systemic antiviral agents is to control symptoms and decrease risk of transmission to partners. There is no treatment to eradicate latent virus. Episodic treatment may be offered to those with new diagnoses or infrequent outbreaks. Treatment should be initiated at onset of prodromal symptoms or within 1 day of appearance of lesions. Daily suppressive therapy may be provided for those with frequent recurrences (≥6/year) or if the patient wants to reduce risk of transmission to uninfected partners.
Routine screening for HSV is not recommended. For symptomatic presentation, HSV-PCR is considered gold standard over viral culture. Serologic testing is available, although is not recommended as a standard screening tool in asymptomatic individuals .
HPV accounts for the majority of newly acquired STIs each year. Seventy-nine million Americans are currently infected with HPV and 14 million people become newly infected each year. Most men and women will get at least one type of HPV at some point in their lives . Incubation period is 3 weeks–8 months. Symptomatic HPV presentation typically includes genital warts or cervical dysplasia.
Genital warts present as flat, papular, or pedunculated lesions most commonly around the anus or vaginal introitus. These lesions can spread, get very large, distort anatomy, or obstruct urethral meatus. Approximately 90 % of all HPV cases will spontaneously resolve within 2 years without long-term sequelae. Even with treatment, some lesions may persist or recur. A small number of warts will undergo malignant transformation and can lead to serious consequences including oral, anal, vulvar, vaginal, penile, oropharyngeal, or cervical cancer.
Diagnosis of anogenital warts is primarily a clinical diagnosis. Treatment may be offered to remove symptomatic warts. This does not eradicate the virus, but may induce wart-free period and likely decreases infectivity. Most warts respond to topical therapy within 3 months. Mucosal warts or very large or coalesced lesions should be referred for removal by a skilled provider with cryoablation, laser ablation, electrocautery, or excision. Partners should be notified and patients should be encouraged to use condoms with all sexual activity to decrease disease transmission.
Papanicolaou (PAP) smear remains the gold standard for cervical cancer screening. Initiation of PAP smears should begin at age 21, regardless of age of onset of sexual activity [30, 31].
Three HPV vaccines, Gardasil (quadrivalent and 9-Valent) and Cervarix (bivalent), have been approved by the FDA for prevention of HPV disease. Only Gardasil has been approved for males. HPV vaccine is recommended by the Advisory Committee on Immunization Practices (ACIP) between 11 and 12 years of age for both males and females; however it can be given as young as 9 and as old as 26 . A three-injection series is administered at 0, 1–2, and 6 months. All three vaccines protect against the two most highly oncogenic subtypes, 16 and 18. Both quadrivalent and 9-valent Gardasil also protect against serotypes 6 and 11, which most commonly cause anogenital warts. 9-valent Gardasil offers 5 additional oncogenic types that primarily affect women (31, 33, 45, 52, and 58).
The vaccine is most beneficial if it is administered prior to sexual debut. Efficacy studies evaluating the vaccines are encouraging—HPV prevalence in teen girls decreased by 56 % in the first 4 years after the vaccine debuted . This suggests potential prevention of tens of thousands of cases of cervical cancer in the future with improved vaccine administration. Despite these data, rates of completion of the three-dose series remain low, a mere 40 % among teenage girls and 22 % among teenage boys .
Infection with T. vaginalis, a motile protozoan, is increasingly prevalent and now thought to be the most common nonviral STI . This infection affects men and women of all ages.
Incubation period is approximately 5–18 days. Asymptomatic carriage commonly occurs. Presentation in females may include vaginal discharge, odor, perineal irritation or pruritis, irregular bleeding, dysuria, cervicitis, and PID. Most men are asymptomatic, but those infected may present with urethritis, epididymitis, or prostatitis. Infection with T. vaginalis has been associated with higher rates of HIV and HSV transmission, cervical neoplasia and adverse pregnancy outcomes [36–38].
Female GU examination often reveals diffusely erythematous, vaginal mucosa; thin, homogenous, “frothy” discharge with pH >4.5 and positive “whiff test” (amine odor test when vaginal fluid combined with 10 % KOH); characteristic “strawberry cervix,” or colpitis macularis, microscopic hemorrhages of the cervix.
CDC recommends screening for trichomonas in HIV-infected females annually. While no formal screening recommendations exist at the present time for screening other patient populations, it is suggested that females in high-risk populations or with high-risk sexual behaviors also be screened.
Diagnosis can be made using wet mount microscopy of vaginal secretions to detect motile trichomonads, although this has low sensitivity of only approximately 50–65 %, [39, 40] requires a microscope and experienced user, and is time-sensitive. Culture is no longer considered the gold standard; rather, NAAT or antigen-detection systems are preferred.