Applied Evidence

An STI upsurge requires a nimble approach to care

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Being fluent in new guidelines helps you meet the challenges of changing disease prevalence, rising antibiotic resistance, and evolving social patterns.


› Focus efforts to prevent sexually transmitted infections (STIs) on patients ages 15 to 24 years—because half of new STIs in the United States occur in this age group. A

› Screen for other STIs, including HIV infection, if a person tests positive for a single STI. A

› Treat STIs by following updated (2021) guidelines developed by the Centers for Disease Control and Prevention. A

Strength of recommendation (SOR)
A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series



Except for a drop in the number of sexually transmitted infections (STIs) early in the COVID-19 pandemic (March and April 2020), the incidence of STIs has been rising throughout this century.1 In 2018, 1 in 5 people in the United States had an STI; 26 million new cases were reported that year, resulting in direct costs of $16 billion—85% of which was for the care of HIV infection.2 Also that year, infection with Chlamydia trachomatis (chlamydia), Trichomonas vaginalis (trichomoniasis), herpesvirus type 2 (genital herpes), and/or human papillomavirus (condylomata acuminata) constituted 97.6% of all prevalent and 93.1% of all incident STIs.3 Almost half (45.5%) of new cases of STIs occur in people between the ages of 15 and 24 years.3

Diagnostic testing for sexually transmitted infections

Three factors—changing social patterns, including the increase of social networking; the ability of antiviral therapy to decrease the spread of HIV, leading to a reduction in condom use; and increasing antibiotic resistance—have converged to force changes in screening and treatment recommendations. In this article, we summarize updated guidance for primary care clinicians from several sources—including the Centers for Disease Control and Prevention (CDC), the US Preventive Services Task Force (USPSTF), and the American Society for Colposcopy and Cervical Pathology (ASCCP)—on diagnosing STIs (TABLE 14-13) and providing guideline-based treatment ­(Table 214). Because of the breadth and complexity of HIV disease, it is not addressed here.

Treatment options for sexually transmitted infections
Treatment options for sexually transmitted infections
Treatment options for sexually transmitted infections


Infection with Chlamydia trachomatis—the most commonly reported bacterial STI in the United States—primarily causes cervicitis in women and proctitis in men, and can cause urethritis and pharyngitis in men and women. Prevalence is highest in sexually active people younger than 24 years.15

Because most infected people are asymptomatic and show no signs of illness on physical exam, screening is recommended for all sexually active women younger than 25 years and all men who have sex with men (MSM).4 No studies have established proper screening intervals; a reasonable approach, therefore, is to repeat screening for patients who have a sexual history that confers a new or persistent risk for infection since their last negative result.

Depending on the location of the infection, symptoms of chlamydia can include vaginal or penile irritation or discharge, dysuria, pelvic or rectal pain, and sore throat. Breakthrough bleeding in a patient who is taking an oral contraceptive should raise suspicion for chlamydia.

Untreated chlamydia can lead to pelvic inflammatory disease (PID), tubo-ovarian abscess, tubal factor infertility, ectopic pregnancy, and chronic pelvic pain. Infection can be transmitted vertically (mother to baby) antenatally, which can cause ophthalmia neonatorum and pneumonia in these newborns.

Diagnosis. The diagnosis of chlamydia is made using nucleic acid amplification testing (NAAT). Specimens can be collected by the clinician or the patient (self collected) using a vaginal, rectal, or oropharyngeal swab, or a combination of these, and can be obtained from urine or liquid-based cytology material.16

Continue to: Treatment


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