STIs

Evidence-Based STI Care for FNPs

1. Topic Overview

Sexually transmitted infections (STIs) represent a significant public health burden and are a core competency for Family Nurse Practitioners (FNPs) in primary care, reproductive health, and emergency settings. FNPs must be proficient in screening, diagnosis, treatment, and counseling based on evidence-based guidelines. High-yield exam topics include recognizing atypical presentations, adhering to CDC treatment regimens, managing co-infections, and implementing preventive strategies like vaccination and PrEP.[1]

2. Key Concepts and Definitions

  • Bacterial STIs: Chlamydia trachomatis, Neisseria gonorrhoeae, Treponema pallidum (Syphilis). These are curable with specific antibiotics.
  • Viral STIs: Human Immunodeficiency Virus (HIV), Herpes Simplex Virus (HSV-2, HSV-1), Human Papillomavirus (HPV), Hepatitis B (HBV). These are manageable but not curable (except HBV which is vaccine-preventable).
  • Parasitic STIs: Trichomonas vaginalis (Trichomoniasis). Curable with metronidazole or tinidazole.
  • Reportable Diseases: Chlamydia, Gonorrhea, Syphilis, HIV, and Hepatitis are reportable to state health departments. The FNP must understand local reporting requirements.[1]
  • Expedited Partner Therapy (EPT): The clinical practice of treating the sex partner(s) of a patient diagnosed with chlamydia or gonorrhea without an independent medical evaluation. Legal in most states.

3. Core Principles & Screening Guidelines

Screening for STIs is often risk-based, but several organizations (CDC, USPSTF) recommend routine screening for certain populations.[2] The FNP must know these guidelines to avoid missing silent infections.

STI Population Recommendation
Chlamydia & Gonorrhea Sexually active women < 25 years Annual NAAT screening. Screen older women with risk factors (new partner, multiple partners).[2]
HIV All patients 15–65 years Opt-out screening at least once. Repeat annually for high-risk patients (MSM, injection drug users).[4]
Syphilis Men who have sex with men (MSM), HIV+ individuals Screen at least annually. Screen all pregnant women at first prenatal visit.[1]
HPV/Cervical Cancer Women 21–65 years Pap smear alone (21–29), Pap + HPV co-testing (30–65).[5]

4. Signs, Symptoms, and Clinical Findings

Many STIs are asymptomatic (especially Chlamydia in women). When symptoms are present, lesion morphology and discharge characteristics are critical for differential diagnosis.

Condition Key Features
Primary Syphilis Painless chancre (classic solitary ulcer with firm, rolled edges) at the site of inoculation. Regional lymphadenopathy.[1]
Genital HSV Painful vesicles/ulcers, dysuria, flu-like symptoms during primary infection. Recurrent outbreaks are common.
HPV (Genital Warts) Painless, fleshy, cauliflower-like growths (condyloma acuminata).
Gonorrhea/Chlamydia Mucopurulent cervicitis/vaginitis, dysuria, abnormal discharge. Often asymptomatic.
Trichomoniasis Profuse, frothy, yellow-green discharge, vaginal itching, "strawberry cervix" on exam.

5. Assessment, Diagnosis, and Evaluation

  • Nucleic Acid Amplification Tests (NAATs): The gold standard for diagnosing Chlamydia trachomatis and Neisseria gonorrhoeae. Can be performed on urine, vaginal, or cervical swabs. Highly sensitive and specific.[1]
  • Syphilis Serology:
    1. Non-treponemal tests (Screening): VDRL or RPR. Titer results correlate with disease activity.
    2. Treponemal tests (Confirmatory): TP-PA, FTA-ABS. Positive for life after infection.
  • HIV Testing: 4th generation antigen/antibody (Ag/Ab) combo tests are standard. Window period: ~2–4 weeks for 4th gen tests. Confirm reactive tests with a Western blot or HIV-1/HIV-2 differentiation assay.[4]
  • Wet Mount (Saline Prep): Used to visualize Trichomonas vaginalis (motile flagellated organisms), clue cells (bacterial vaginosis), and yeast (candida). NAAT for Trichomonas is more sensitive.

6. Treatment, Interventions, and Patient Care

Treatment must follow current CDC guidelines to combat antimicrobial resistance, especially for N. gonorrhoeae.[1]

  • Chlamydia:
    • First-line: Azithromycin 1g PO single dose OR Doxycycline 100mg PO BID x7 days.
    • Pregnancy: Azithromycin 1g PO single dose. Doxycycline is contraindicated.
  • Gonorrhea:
    • First-line: Ceftriaxone 500mg IM single dose (250mg if <150kg). Dual therapy is no longer routinely recommended for uncomplicated urogenital/anorectal gonorrhea, but co-treatment for chlamydia is essential if infection hasn't been ruled out.
    • Resistance: Fluoroquinolones are no longer recommended due to widespread resistance.
  • Syphilis:
    • Early (Primary, Secondary, Early Latent): Benzathine Penicillin G 2.4 million units IM x1 dose.
    • Late Latent: 7.2 million units total (3 doses of 2.4 million units IM each at 1-week intervals).
    • Neuro/Ocular: Aqueous crystalline Penicillin G IV.
    • Jarisch-Herxheimer Reaction: Acute febrile reaction occurring within 24 hours of treatment. Manage supportively.
  • HSV:
    • Primary Episode: Acyclovir 400mg TID x7-10d or Valacyclovir 1g BID x7-10d.
    • Suppressive Therapy: Valacyclovir 500mg daily (reduces transmission risk).
  • Trichomoniasis: Metronidazole 2g PO single dose or Tinidazole 2g PO single dose. Treat sexual partners.[1]
  • HPV: No cure for the virus. Treat visible warts (cryotherapy, TCA, imiquimod). Prevention is key: Gardasil 9 vaccine for males and females (routine at 11-12 years, catch-up to 26-45 years).[5]
  • HIV: Initiate antiretroviral therapy (ART) as soon as possible. Refer to an HIV specialist. PrEP (Pre-exposure Prophylaxis): Tenofovir/Emtricitabine (Truvada/Descovy) daily for high-risk individuals.[4]

7. Safety Precautions and Complications

  • Pelvic Inflammatory Disease (PID): A direct complication of untreated Chlamydia or Gonorrhea. Leads to infertility, ectopic pregnancy, and chronic pelvic pain. Must be treated empirically in sexually active young women with uterine/adnexal tenderness.[1]
  • Congenital Syphilis: Devastating but preventable. All pregnant women must be screened. Penicillin is the only recommended treatment during pregnancy.
  • Neurosyphilis: Can occur at any stage of syphilis. Consider in patients with neurologic or ocular symptoms (meningitis, vision loss, hearing loss).
  • Cervical Cancer: Almost exclusively caused by high-risk HPV types (16, 18). Screening via Pap/HPV co-testing is crucial. Vaccination is primary prevention.[5]
  • Disseminated Gonococcal Infection (DGI): Rare but serious; presents with dermatitis (pustules), tenosynovitis, and septic arthritis.

8. Exam Tips and High-Yield Points

  • Co-infection is common: A patient with syphilis, gonorrhea, or chlamydia should be tested for HIV. Conversely, a patient with HIV should be screened for all STIs.
  • "The Great Imitator": Syphilis can present with a wide variety of rashes (secondary stage: maculopapular rash on palms and soles). Always ask about rash in patients with suspected STIs.
  • Mnemonic for Syphilis Stages: "Primary (Chancre), Secondary (Rash), Latent (Silent), Tertiary (Gumma/Neurosy)."
  • Painless vs. Painful: Syphilis chancre = painless. HSV ulcer = painful. This is a classic differentiating point.
  • Window Period: If initial HIV test is negative but exposure was within the last 4 weeks, repeat the test in 1-3 months. A 4th generation Ag/Ab test is the preferred screening test.[4]
  • Pregnancy: Doxycycline and Fluoroquinolones are contraindicated. Ceftriaxone, Azithromycin, Metronidazole, and Acyclovir are generally considered safe.
  • EPT: Legal in most states for chlamydia and gonorrhea. The partner does not need to be seen by a provider. Give the patient a prescription or medication for their partner.

9. References & Sources

  1. Workowski, K. A., Bachmann, L. H., Chan, P. A., Johnston, C. M., Muzny, C. A., Park, I., Reno, H., Zenilman, J. M., & Bolan, G. A. (2021). Sexually Transmitted Infections Treatment Guidelines, 2021. MMWR. Recommendations and Reports, 70(4), 1–187. https://doi.org/10.15585/mmwr.rr7004a1
  2. US Preventive Services Task Force. (2021). Screening for Chlamydia and Gonorrhea: US Preventive Services Task Force Recommendation Statement. JAMA, 326(10), 949–956. https://jamanetwork.com/journals/jama/fullarticle/2784136
  3. Centers for Disease Control and Prevention. (2015). Sexually transmitted diseases treatment guidelines, 2015. MMWR, 64(RR-03), 1–137. https://pubmed.ncbi.nlm.nih.gov/26042815/
  4. Branson, B. M., Handsfield, H. H., Lampe, M. A., Janssen, R. S., Taylor, A. W., Lyss, S. B., & Clark, J. E. (2006). Revised recommendations for HIV testing of adults, adolescents, and pregnant women in health-care settings. MMWR, 55(RR-14), 1–17. https://pubmed.ncbi.nlm.nih.gov/16988643/
  5. Markowitz, L. E., Dunne, E. F., Saraiya, M., Chesson, H. W., Curtis, C. R., Gee, J., Bocchini, J. A., & Unger, E. R. (2014). Human papillomavirus vaccination: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR, 63(RR-05), 1–30. https://pubmed.ncbi.nlm.nih.gov/24918641/

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